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1987 GT coolant fan temp?? by NightMare Cruiser
Started on: 03-16-2015 01:41 PM
Replies: 83 (2480 views)
Last post by: Patrick on 03-24-2015 04:34 PM
Patrick
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Report this Post03-21-2015 12:03 AM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by thesameguy:

I did not say cooler ones didn't exist, I said the SW555 is the coolest one GM specified.


And I was just sharing (not endorsing) what other fan switches that Rodney offers for Fieros.
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Report this Post03-21-2015 10:19 AM Click Here to See the Profile for fierosoundClick Here to visit fierosound's HomePageClick Here to Email fierosoundSend a Private Message to fierosoundEdit/Delete MessageReply w/QuoteDirect Link to This Post
Just because GM "did it that way" doesn't mean it's always best. They do lots of goofy things for different reasons.
The "hot engine" is mainly to reduce emissions to make EPA happy. The 195F thermostat is geared as best for low emissions.

But I'm not sure what the point is to "overheat" the engine before kicking on the radiator fan.
Why the BIG swings in engine temperature from "normal" to hot, fan kicks in, then back down to "normal" - the GM design?
(my Dodge Caravan with 3.3L V6 certainly does not do this under normal operation - temp gauge is always steady)
Search Google - every GM owner (even with brand new Cobalt) is asking why their car "overheats" and the radiator fan still isn't coming on.

They've had the same discussion in the Corvette forums (with less arguing) about engines running hot.
GM also had those engines hitting +230F before kicking on the fans. Those owners also worry about damaging their engine.
All the Corvette parts houses have lower temp switches to pair with the stock 195F thermostat or the 180F thermostat people in the "banana belts" prefer.

Been there - it feels bad sitting in stop-and-go traffic on a hot day watching that temp gauge climb toward the RED and feeling helpless as the engine starts acting weird.
I've seen the engine so hot that the oil on the rockers just ran off in drops like water on a duck's back - not lubricating very well when it does that.
And without A/C in my GT - I could do nothing at all about it (the A/C kicks the radiator fan ON when activated).
This was years ago - I installed a manual grounding switch for the fan relay afterward - later changed to lower temp fan switch.

In both my cars, I'm running a 180F thermostat paired with a matching switch from Dickman and it works perfectly without the big normal/hot temp. swings.
Mind you, I'm not running stock engines so I need the lower 180F engine temp because it helps with ping and knock.

The 3.4L V6 in the GT is 9.5 C.R. plus is running boost of 6-8 lbs.
The 3.4L SD4 in the Indy is running 10.5 C.R. with 91 octane gas.

[This message has been edited by fierosound (edited 03-21-2015).]

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quote
Originally posted by dobey:

This is one of the benefits of the active shutter systems that some new cars have, for fuel economy. When starting cold, the shutters are closed, which prevents air flowing through the radiator, so it helps the system to reach operating temperature a little faster than without a closed shutter.


Yes - its helps with faster engine warmup.

I suppose then that ALL Canadian cars SHOULD come with this, because winter driving at -30C temperatures on the highway is definitely more than equivalent to having the radiator fan on all the time. The shutters could be set to be closed at that time, otherwise, by some opinions, you are "over-cooling" your engine for the entire winter season (in areas where there really is winter).

It sure doesn't seem to work that way, because the engine provides plenty of heat AND runs properly if the cooling system and thermostat are working properly - better in fact than on hot summer days.

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Report this Post03-21-2015 07:09 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierosound:
Yes - its helps with faster engine warmup.

I suppose then that ALL Canadian cars SHOULD come with this, because winter driving at -30C temperatures on the highway is definitely more than equivalent to having the radiator fan on all the time. The shutters could be set to be closed at that time, otherwise, by some opinions, you are "over-cooling" your engine for the entire winter season (in areas where there really is winter).

It sure doesn't seem to work that way, because the engine provides plenty of heat AND runs properly if the cooling system and thermostat are working properly - better in fact than on hot summer days.


ALL cars SHOULD come with the shutters, regardless of whether in Canada or somewhere near the equator. Properly designed and function shutters allow the engine to operate much more efficiently, and improve aerodynamics which increases MPG.

Overcooling doesn't necessarily mean that the engine won't generate any heat, or that it won't run reasonably well. It does mean that it will run less efficiently. That is exactly one of the reasons why fuel economy goes down in the winter. The engine doesn't necessarily operate at it's optimum temperature, and colder air temperatures mean more dense air going into the engine, which means more fuel to maintain the A/F ratio.
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Report this Post03-22-2015 12:41 AM Click Here to See the Profile for fierosoundClick Here to visit fierosound's HomePageClick Here to Email fierosoundSend a Private Message to fierosoundEdit/Delete MessageReply w/QuoteDirect Link to This Post
Old news. The PRIMARY reason they introduced active shutter systems is when closed at highway speeds they force the air around the vehicle to improve mileage.

[This message has been edited by fierosound (edited 03-22-2015).]

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Report this Post03-22-2015 03:44 AM Click Here to See the Profile for PonnariSend a Private Message to PonnariEdit/Delete MessageReply w/QuoteDirect Link to This Post
It is exactly as "thesameguy" explained it, with a 195 degree stat, that is the coldest temp the coolant will start circulating through the system at.
there are some regulars on here that should spend more time learning than arguing!
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Report this Post03-22-2015 04:42 AM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Ponnari:

...with a 195 degree stat, that is the coldest temp the coolant will start circulating through the system at.


Who was "arguing" about that?
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Report this Post03-22-2015 10:27 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

Who was "arguing" about that?


It's been argued that it's the temperature the system is designed to operate at, rather than just the minimum temperature of coolant circulation. If it was the temperature the engine was designed to operate at, for optimal design efficiency given the conditions the car was designed to be used in, the fan switch would be more like 205/190 or somewhere around there, and the thermostat would probably be around 180-185. The stock engine and cooling system is designed to operate optimally around 215 degrees, under normal conditions.

If your car is an unmodified stock vehicle, and you are using it in standard operating conditions for a stock street driven car, then sticking with stock replacement parts is probably the best thing to do. If you have modifications which would move the optimal operating efficiency of the engine to a lower temperature, then a change in thermostat and fan switch might be necessary. They should both be changed at the same time when changing the operational temperature range of the cooling system, if modifications to the engine necessitate such change.

Even the modern all aluminum LSx/Ecotec/etc engines are designed to operate at around 210-215 degrees under normal conditions.
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Report this Post03-22-2015 10:52 AM Click Here to See the Profile for fierosoundClick Here to visit fierosound's HomePageClick Here to Email fierosoundSend a Private Message to fierosoundEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Ponnari:

...with a 195 degree stat, that is the coldest temp the coolant will start circulating through the system at.



 
quote
Originally posted by Patrick:

Who was "arguing" about that?


Agreed. Nobody is arguing that.

As designed, the engine temperature swings up to 235F in hot slow traffic before the fan kicks on in a last minute effort to prevent boiling over (antifreeze in a pressurized system will boil at around 262F). GM allows the engine to idle "hot" to meet EPA regulations. Anyone who is fine with that (or lives in California) can leave their system stock if they want. (why didn't GM use a 220F thermostat to reduce emissions even more?)

Just saying that we think that helping the engine maintain a more CONSISTENT operating temp of around 195F is better for the engine's longevity.
Those who'd prefer a more even temperature range can change the fan switch and have the fan come on at 210F. This is not a "crime".
The engine will still be running at the temp of the thermostat so you're not over-cooling the engine and will still have low emissions.
Fan Switch http://rodneydickman.com/ca...th=22&products_id=88

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Report this Post03-22-2015 02:01 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierosound:
Just saying that we think that helping the engine maintain a more CONSISTENT operating temp of around 195F is better for the engine's longevity.
Those who'd prefer a more even temperature range can change the fan switch and have the fan come on at 210F. This is not a "crime".
The engine will still be running at the temp of the thermostat so you're not over-cooling the engine and will still have low emissions.
Fan Switch http://rodneydickman.com/ca...th=22&products_id=88


Depending on where you live, it may in fact be a "crime," if it results in higher hydrocarbons emissions from the engine.

Is there any documented evidence that changing the cooling system to maintain the temperature closer to 195F is actually better for the engine? Not trying to argue aobut it, but genuinely interested, as there are plenty of cars that have been running the stock equipment for over 30 years with no engine failures, and over 200K miles on the clock. If there's actual performance/emissions/efficiency benefits, it would be nice to see what they are, in standard documentation (dyno chart, emissions chart, MPG over XX miles, etc…), so that others can compare results.

That said, if you really want to maintain the engine at around 195F, then you need to change the thermostat to a 180-185 thermostat as well. As it's a mechanical element, it is not a digital on/off device, and it opens and closes over an analog range. If the coolant temperature is maintained at 195F, with the stock thermostat, you will not have full coolant flow, as thesameguy was explaining. That may be fine if you live in a cooler climate where you can get sufficient heat exchange happening even with partial flow, or in higher altitudes where the engine will run a little cooler anyway, as it's burning less fuel due to the lower air density. In general, if you want to lower the regulated temperature the engine operates at though, you need to adjust both the thermostat and the fan switch.
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quote
Originally posted by dobey:

Depending on where you live, it may in fact be a "crime," if it results in higher hydrocarbons emissions from the engine.


Maybe California.

I don't know, when smog testing - do they wait until your engine hits 235F and the fan kicks on to take the reading?
Do they check to see what temperature the fan kicks in? Or is idling at 195F "normal temp" all they look at?

Emissions likely increase a bit if you went to the lower temp. thermostats. But at the normal 195F the engine is tuned for, emissions will be within specs.
Then the engine idling at a temp 195F even with the fan running continuously will pass emissions (unless something else is wrong ie: bad EGR).

Yeah we know, GM's "normal operating range" for most engines today is 195-235F (a 40 degree swing).
You're fine with that, I'd prefer keeping engine temp more stable around the 195F mark even in hot slow traffic.

So when someone with a new GM pulls into the dealership out of stop-and-go traffic with the needle just under the red and the fans kick in, they'll be told - "that's normal". If they're fine with that answer, so be it - doesn't bother me - it's THEIR car.

GM has been "dumbing down" the temp gauges to almost being an analog idiot light because too many people complained their engine was "running too hot".

[This message has been edited by fierosound (edited 03-22-2015).]

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quote
Originally posted by dobey:

That said, if you really want to maintain the engine at around 195F, then you need to change the thermostat to a 180-185 thermostat as well.



Decent writeup here - I don't agree with all of it.
You can discount it all if you want (it's not an engineering paper).
http://www.gmtips.com/3rd-d...cool/stat-theory.htm

It's a cheap enough experiment to get Dickman's switch that he sells to use with the 195F thermostat and try for yourself.
Install it and drive in stop-n-go traffic on a HOT day with A/C off (so you don't have the fan running continuously).

[This message has been edited by fierosound (edited 03-22-2015).]

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Report this Post03-22-2015 05:22 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierosound:
Maybe California.

I don't know, when smog testing - do they wait until your engine hits 235F and the fan kicks on to take the reading?
Do they check to see what temperature the fan kicks in? Or is idling at 195F "normal temp" all they look at?

Emissions likely increase a bit if you went to the lower temp. thermostats. But at the normal 195F the engine is tuned for, emissions will be within specs.
Then the engine idling at a temp 195F even with the fan running continuously will pass emissions (unless something else is wrong ie: bad EGR).

Yeah we know, GM's "normal operating range" for most engines today is 195-235F (a 40 degree swing).
You're fine with that, I'd prefer keeping engine temp more stable around the 195F mark even in hot slow traffic.

So when someone with a new GM pulls into the dealership out of stop-and-go traffic with the needle just under the red and the fans kick in, they'll be told - "that's normal". If they're fine with that answer, so be it - doesn't bother me - it's THEIR car.

GM has been "dumbing down" the temp gauges to almost being an analog idiot light because too many people complained their engine was "running too hot".


The normal way to bring a car to normal operating temperature is to have the fan come on and go off twice, after a cold start. Most emissions tests I've ever had to do, have been done on a dyno platform, and readings were taken at idle and at speed, when the car was in normal operating temperature range. I suspect most places these days that do emissions tests, have computer screens that tell them how to perform the test.

The engine is not "tuned for 195F" as it is installed from the factory. It is "tuned for" around 215F. That's why it has a 195F thermostat, and a 235F fan switch.

New GM cars don't have the fan come on as high as the Fiero did. Certainly nowhere near the red mark on the gauge. If you take a new car into the dealer with the temp gauge pointing somewhere near a red line on the gauge, and complain about the fan not coming on until that point, they will not say that is normal. It is not normal at all. All new GM vehicles have aluminum heads. The temperature where damage can occur is lower than on the iron head engines of the old days. That's what thesameguy was saying.

If you really want to "maintain 195F in hot slow traffic" then you should also install a colder thermostat, so the system will operate more efficiently in that situation, and the fan will not come on as often. It probably wouldn't be a terrible idea to upgrade the fan to a 2-stage fan that flows more air, either.
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Report this Post03-22-2015 05:29 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierosound:
Decent writeup here - I don't agree with all of it.
You can discount it all if you want (it's not an engineering paper).
http://www.gmtips.com/3rd-d...cool/stat-theory.htm

It's a cheap enough experiment to get Dickman's switch that he sells to use with the 195F thermostat and try for yourself.
Install it and drive in stop-n-go traffic on a HOT day. (you can always put the factory switch back in afterwards if you want).


I'll take a look at it. I'm sure I probably won't agree with all of it either.

My car is not drivable at the moment (it's been down for a while due to a blown head gasket, and hasn't been able to start in some time now). I'm building a high performance LS4 swap to go in it. Today, I just drained the radiator and would have pulled it out, but had some trouble getting the stamped piece holding it in at the top out, so had to come in and search to see what I'm missing. The fan is controlled by the ECM, and I just ordered a Volvo 2-stage fan to use instead, so I'll be able to just change what temps the fan comes on at for low or high speed, in the programming. I'm not sure what thermostat I'll use in it yet, though.
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quote
Originally posted by dobey:

My car is not drivable at the moment (it's been down for a while due to a blown head gasket, and hasn't been able to start in some time now). I'm building a high performance LS4 swap to go in it. Today, I just drained the radiator and would have pulled it out, but had some trouble getting the stamped piece holding it in at the top out, so had to come in and search to see what I'm missing. The fan is controlled by the ECM, and I just ordered a Volvo 2-stage fan to use instead, so I'll be able to just change what temps the fan comes on at for low or high speed, in the programming. I'm not sure what thermostat I'll use in it yet, though.


Blown head gasket from overheating?

I suppose you will be programming the ECM to kick on the fans at a lower temp than 235F?


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Report this Post03-22-2015 06:08 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierosound:
Blown head gasket from overheating?

I suppose you will be programming the ECM to kick on the fans at a lower temp than 235F?


Probably from overheating, but the overheating isn't a result of the fan switch. The fan would come on just fine. I think corrosion in the cooling system was probably the main cause.

Yes, the LS4 is aluminum block and heads, and I'm building it to run a higher compression ratio. Being nowhere near stock, the stock metrics won't necessarily make sense. I'm not sure what temperatures I'll set the fan speeds at yet. I'm installing piston cooling squirters in the block, and will be installing an oil cooler in the passenger fender well too. GM's current engines also flow the coolant in the other direction from the old engines like the 2.8/duke, IIRC, which removes heat from the engine a bit more efficiently.
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Report this Post03-22-2015 07:40 PM Click Here to See the Profile for David HambletonClick Here to Email David HambletonSend a Private Message to David HambletonEdit/Delete MessageReply w/QuoteDirect Link to This Post
I think that most people consider the 'normal' temperature to be whatever point the needle stops at when they've been driving without stopping; for example cruising down a highway. That point stays pretty consistent regardless of outside temperature once that point has been reached as long as the car isn't stopped for very long.

It seems logical to assume that the point noted above would be the ideal engine operating temperature, since the engine should be at it's best efficiency when it's moving the car along.

The disconcerting thing about Fieros compared to other vehicles is how much hotter the gauge gets when the car is not moving. In over 40 years of driving a lot of different GM and other vehicles, I've never noticed that kind of increase in other vehicles. I have an '84 SE 4 speed since new, an '86 2.5 5 speed and '88 Formula 5 speed and always wonder why they should get so hot before the fan comes on when other vehicles don't. If the reason is for emissions, what did they do for other engines? We had 4 different GM cars with the 2.5 litre engine in the '80s. Never had any overheating issues.
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Report this Post03-22-2015 08:20 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by David Hambleton:

I think that most people consider the 'normal' temperature to be whatever point the needle stops at when they've been driving without stopping; for example cruising down a highway. That point stays pretty consistent regardless of outside temperature once that point has been reached as long as the car isn't stopped for very long.

It seems logical to assume that the point noted above would be the ideal engine operating temperature, since the engine should be at it's best efficiency when it's moving the car along.

The disconcerting thing about Fieros compared to other vehicles is how much hotter the gauge gets when the car is not moving. In over 40 years of driving a lot of different GM and other vehicles, I've never noticed that kind of increase in other vehicles. I have an '84 SE 4 speed since new, an '86 2.5 5 speed and '88 Formula 5 speed and always wonder why they should get so hot before the fan comes on when other vehicles don't. If the reason is for emissions, what did they do for other engines? We had 4 different GM cars with the 2.5 litre engine in the '80s. Never had any overheating issues.


How many of those other GM cars have 10 feet of tubing between the radiator and the engine? In all the front engined cars, you'll notice the temperature "issue" less, because there is significantly less distance between the radiator and engine, less coolant in the system, and the radiator fan also results in the air which passes through the radiator, travelling over the engine, which helps lift some heat off the thing. In the Fiero, the engine is in the rear, which means air doesn't flow over the engine when fan is on and you're stopped, and the greater coolant capacity and tube length means the ability for the system to remove heat from the engine is handicapped. You'll notice the temperature in the Fiero more, because it will stay at a higher temp a bit longer than the front-engine cars do; even the ones with the same fan switch and thermostat as the Fiero.
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quote
Originally posted by dobey:


How many of those other GM cars have 10 feet of tubing between the radiator and the engine? In all the front engined cars, you'll notice the temperature "issue" less, because there is significantly less distance between the radiator and engine, less coolant in the system, and the radiator fan also results in the air which passes through the radiator, travelling over the engine, which helps lift some heat off the thing. In the Fiero, the engine is in the rear, which means air doesn't flow over the engine when fan is on and you're stopped, and the greater coolant capacity and tube length means the ability for the system to remove heat from the engine is handicapped. You'll notice the temperature in the Fiero more, because it will stay at a higher temp a bit longer than the front-engine cars do; even the ones with the same fan switch and thermostat as the Fiero.


The only handicap seems to be the high temperature at which the fan turns on. If the fan is turned on with a manual switch or the A/C function when the gauge starts to climb, the system seems quite capable of lowering the temperature back to 'normal'. If the system waits until the fan turns on by the temperature switch, the system still lowers the temperature back to normal. My question is why wait until it gets so hot?

[This message has been edited by David Hambleton (edited 03-22-2015).]

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Report this Post03-23-2015 02:24 AM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by David Hambleton:

I think that most people consider the 'normal' temperature to be whatever point the needle stops at when they've been driving without stopping; for example cruising down a highway. That point stays pretty consistent regardless of outside temperature once that point has been reached as long as the car isn't stopped for very long.

It seems logical to assume that the point noted above would be the ideal engine operating temperature, since the engine should be at it's best efficiency when it's moving the car along.


As long as a fully functioning 195° thermostat is installed.... absolutely!

I've mentioned more than once that Rodney's 210° on and 200° off fan switch never turns the rad fan on while any of my three Fieros are actually moving. So how this fan switch is contributing to my engines running below their "ideal" operating temperature (with a 195° thermostat) is beyond me.

[This message has been edited by Patrick (edited 03-23-2015).]

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quote
Originally posted by Patrick:

As long as a fully functioning 195° thermostat is installed.... absolutely!

I've mentioned more than once that Rodney's 210° on and 200° off fan switch never turns the rad fan on while any of my three Fieros are actually moving. So how this fan switch is contributing to my engines running below their "ideal" operating temperature (with a 195° thermostat) is beyond me.



The "ideal" temperature (stock) is about 215F. With a 210 switch, your coolant will almost never see that temperature. With the fan not coming on while moving, it may not be "contributing" to that in that condition, but it will contribute to that when the car is sitting and the fan does need to come on.
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quote
Originally posted by David Hambleton:
The only handicap seems to be the high temperature at which the fan turns on. If the fan is turned on with a manual switch or the A/C function when the gauge starts to climb, the system seems quite capable of lowering the temperature back to 'normal'. If the system waits until the fan turns on by the temperature switch, the system still lowers the temperature back to normal. My question is why wait until it gets so hot?


I don't know the original part number, and I don't have any parts manuals for other GM cars of the time, but I'm pretty sure the same switch/thermostat combination was used on plenty of GM vehicles at the same time.

235F in a properly functioning pressurized coolant system on an iron headed iron block engine, is not that hot. It's still got another 30-40 degrees before any damage can occur, and the pressurized coolant/water mix starts boiling. Also, the temp gauge on the Fiero is notoriously inaccurate. The gauge may look like the engine is becoming hotter than it really is, especially after 25-30 years.

The big handicap in the Fiero is really the coolant tubes, which can easily be dented enough to cause overheating issues (over 235F).
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quote
Originally posted by David Hambleton:

The only handicap seems to be the high temperature at which the fan turns on. If the fan is turned on with a manual switch or the A/C function when the gauge starts to climb, the system seems quite capable of lowering the temperature back to 'normal'. If the system waits until the fan turns on by the temperature switch, the system still lowers the temperature back to normal. My question is why wait until it gets so hot?



Agreed. Keep in mind that people with A/C on their cars will rarely see this problem - because they most likely have the A/C ON because it's a hot day, and so they already have the fan running continuously. In an sense, they have MANUALLY turned on the radiator fan and have got around GM's "design". In a car without A/C you helplessly watch that temp gauge climb.


 
quote
Originally posted by Patrick:

As long as a fully functioning 195° thermostat is installed.... absolutely!

I've mentioned more than once that Rodney's 210° on and 200° off fan switch never turns the rad fan on while any of my three Fieros are actually moving. So how this fan switch is contributing to my engines running below their "ideal" operating temperature (with a 195° thermostat) is beyond me.



We're in agreement.

Look at it this way - as the system is setup stock, with the car is sitting in traffic and the thermostat is wide open. The water pump is circulating coolant and the entire system from engine to radiator AND back heats up. There IS NO water cooling occuring at all (as if you didn't even have a radiator)! When the fan finally kicks on it's almost a last ditch effort to prevent boiling over.

By getting the fan going a little sooner, there's cooler water available "to make a difference" when that thermostat starts opening.

Changing the switch is a good solution and it's relatively cheap to try by anyone who seen this occur on their car and it will not hurt anything. It's like turning on your A/C to get the radiator fan going (only it will be automatic).

The engine will not be overcooled because of the thermostat. It's job is to open and close to maintain your engine at operating temperature. IT is your engine's temperature control - not the radiator fan switch.

[This message has been edited by fierosound (edited 03-23-2015).]

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quote
Originally posted by fierosound:
We're in agreement.

Look at it this way - as the system is setup stock, with the car is sitting in traffic and the thermostat is wide open. The water pump is circulating coolant and the entire system from engine to radiator AND back heats up. There IS NO water cooling occuring at all (as if you didn't even have a radiator)! When the fan finally kicks on it's almost a last ditch effort to prevent boiling over.

By getting the fan going a little sooner, there's cooler water available "to make a difference" when that thermostat starts opening.

Changing the switch is a good solution and it's relatively cheap to try by anyone who seen this occur on their car and it will not hurt anything. It's like turning on your A/C to get the radiator fan going (only it will be automatic).

The engine will not be overcooled because of the thermostat. It's job is to open and close to maintain your engine at operating temperature. IT is your engine's temperature control - not the radiator fan switch.


The thermostat is not the temperature control. You just said as much in your exact same post. If the temperature is going to keep climbing with the thermostat fully open, with the car sitting still, and the fan not turning on, the temperature is not being regulated.

The thermostat, fan switch, fan, water pump, and radiator, all work together to regulate the temperature. The A/C situation is a special condition. Unplug your fan, turn on the A/C, and watch how poorly your A/C will perform, and how the heat from the condenser will end up soaking into the radiator. This is why many other cars have a separate fan for the A/C condenser.

The fan is hardly a last ditch effort to prevent boiling over, as the stock fan switch kicks in about 30-40 degrees prior to that possibly happening. It would need to come on at like 250 degrees to call it that.
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quote
Originally posted by dobey:

The A/C situation is a special condition. Unplug your fan, turn on the A/C, and watch how poorly your A/C will perform, and how the heat from the condenser will end up soaking into the radiator. This is why many other cars have a separate fan for the A/C condenser.


Luckily - it also cools the radiator and prevents the engine from climbing to 235F.

Lets' agree to disagree. You're happy with the stock setup (which you will no longer have) fine.

This thread was just showing an solution for those who aren't happy with it.

[This message has been edited by fierosound (edited 03-23-2015).]

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Report this Post03-23-2015 09:56 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierosound:
Luckily - it also cools the radiator and prevents the engine from climbing to 235F.

Lets' agree to disagree. You're happy with the stock setup (which you will no longer have) fine.

This thread was just showing an solution for those who aren't happy with it.


I never said I was happy with the stock setup. I'm just trying to help clarify the many confusing and conflicting statements which have been made in this thread.

The OP was simply asking what temperature the fan kicks on at, and that was answered within the first 3 posts. Other people jumped in and started going on about installing a 210F switch because it's "better" and making conflicting statements about how the cooling system works.

If you want to have your engine stay around 195F, then that's fine, but I think you need to install the lower temp thermostat along with the 210F fan switch, to truly accomplish that. I was just trying to help provide technically accurate information regarding cooling system functionality and which components do what.
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Report this Post03-23-2015 01:29 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
This is literally the craziest thread I have ever seen.

I cannot fathom how there is so much misunderstanding of 40 year old automotive technology. It's madness.

Making it even crazier is that this same conversation happened on this forum in 2010 with one "I believe what I want to believe" contingent arguing about how thermostats and fans work and another "this is how cars actually work" contingent pointing out the issues with that opinion. History DOES repeat itself!

I will GUARANTEE that more people have blown out head gaskets from a failure to change coolant every two years (or four or five, if you use new stuff) than because their iron block, iron head motor overheated from a 235 degree fan switch. GUARANTEE it.

[This message has been edited by thesameguy (edited 03-23-2015).]

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quote
Originally posted by thesameguy:
I will GUARANTEE that more people have blown out head gaskets from a failure to change coolant every two years (or four or five, if you use new stuff) than because their iron block, iron head motor overheated from a 235 degree fan switch. GUARANTEE it.


Pretty sure that, plus dented coolant tube is what killed mine. I'm sure my enjoyment of the exhaust note and hitting the rev limiter weren't helpful either.
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quote
Originally posted by thesameguy:

I will GUARANTEE that more people have blown out head gaskets from a failure to change coolant every two years (or four or five, if you use new stuff) than because their iron block, iron head motor overheated from a 235 degree fan switch. GUARANTEE it.



Is there a technical reason 'old' antifreeze would weaken head gaskets?

I thought the most common reason for 2.5 litre gaskets failing was the head bolt under the air cleaner housing breaking. I had one replaced in my '84 SE under warranty and one replaced in my '86 2.5 litre. I would have thought a stronger bolt would have been installed by the time '86 engines were being made...

[This message has been edited by David Hambleton (edited 03-23-2015).]

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quote
Originally posted by thesameguy:

This is literally the craziest thread I have ever seen.


Tell me about it... There are a couple guys who are critical of a fan switch that has NO bearing on the operating temperature of the engine when the car is in use/motion. Nutsville man!
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Report this Post03-23-2015 10:33 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by David Hambleton:
Is there a technical reason 'old' antifreeze would weaken head gaskets?

I thought the most common reason for 2.5 litre gaskets failing was the head bolt under the air cleaner housing breaking. I had one replaced in my '84 SE under warranty and one replaced in my '86 2.5 litre. I would have thought a stronger bolt would have been installed by the time '86 engines were being made...


The proper coolant mixture is 50/50 antifreeze and distilled water. It does not have an infinite life span. Over time, oxidation occurs, and it picks up minerals from inside the engine. Periodic flush/fill keeps the coolant clean of excess minerals and debris, and helps prevent corrosion. Aged coolant will result in increased corrosion in the system, and provide a greater risk to head gasket failure. As the head/block mating surface is one of the places of the engine which sees the greatest amount of heat stress, the gasket is one of the first points of failure, in terms of coolant issues.

The 87-88 engines were a bit different than the 84-86 engines. For the 2.5, if that head bolt was a common issue, it might have been resolved with the changes in 87.
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Report this Post03-23-2015 10:41 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

Tell me about it... There are a couple guys who are critical of a fan switch that has NO bearing on the operating temperature of the engine when the car is in use/motion. Nutsville man!


Your fan or fan switch is damaged and doesn't work? :P

If your fan doesn't come on, does it even matter if it comes on at 210F, or 235F? It has NO bearing on the operating temperature of the engine, when your car is in use/motion, right? Might as well just unplug the fan, and increase the service life of your alternator and battery, since it's not useful.

I don't really care what fan switch you use. But if your goal is to maintain a 195F temperature (which it's been claimed the Fiero engine is designed to operate at and maintain), then really you should be running a 180F thermostat, along with the 210F fan switch. If your car stays under 195F and the fan never comes on, that's fine, but arguing that the lower temp fan switch is somehow better, though it does absolutely nothing for your car, is also pointless. And that's basically what you've been doing this whole thread.
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Report this Post03-23-2015 11:20 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dobey:

If your fan doesn't come on...


I never said that.

 
quote
Originally posted by dobey:

if your goal is to maintain a 195F temperature...


I never said that either.

 
quote
Originally posted by dobey:

...arguing that the lower temp fan switch is somehow better, though it does absolutely nothing for your car, is also pointless. And that's basically what you've been doing this whole thread.


...

Dobey, I hope you're just kidding around. Seriously, I hope you're just kidding... because otherwise you haven't read what I've stated at all.

 
quote
Originally posted by Patrick:

When any of my Fieros are being driven, even on hot summer days, Rodney's 210° on and 200° off fan switch never turns the fan on while the car is moving.

Please explain how this switch contributes to lowering the operating temperature of my engine when it doesn't even do anything while the car is actually being driven?


I don't care if the coolant temperature gets up to 210° while I'm sitting still idling, but I don't want it reaching 235° (along with the associated increase in coolant pressure). And that's why I use this particular fan switch. It works great to keep the engine from overheating during long sessions of idling in summer traffic jams.

Why bother stressing (up to) 31 year old cooling system components more than necessary? What's the potential benefit of that? I see none... nada... zilch.

[This message has been edited by Patrick (edited 03-24-2015).]

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quote
Originally posted by Patrick:(along with the associated increase in coolant pressure).


That is not how it works either. The cooling system is kept under specific pressure (just under 15psi) in order to increase the boiling point of the system. Without proper pressure in the system, the system would boil at a much lower temperature than 235 degrees. Any time the system pressure exceeds 16psi (IIRC, this is a common pressure), the radiator cap vents excess fluid into the overflow tank. When the system cools, fluid is sucked back into the system exactly the same way it came out. At all times, the system should be operating just a few psi lower than the cap is rated for - there is only a couple psi difference in any properly behaving cooling system. The water pump is as much or more a contributor to system pressure as heat is.

 
quote
Why bother stressing (up to) 31 year old cooling system components more than necessary? What's the potential benefit of that? I see none... nada... zilch.


Because you're not. A properly maintained car runs in a remarkably narrow window and is designed to do exactly that more or less indefinitely. Circumventing or modifying systems because of the way you feel and not because there is an engineering reason to do it is just wasting money - and in this case maybe wasting gas and wasting the air we all breathe and actually putting unnecessary stress on components like the fan and catalytic converter.

Somehow your car made it two or three decades before you decided it was running too hot. Don't you think there is some actual logic for you to follow there?

[This message has been edited by thesameguy (edited 03-24-2015).]

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quote
Originally posted by thesameguy:

The cooling system is kept under specific pressure (just under 15psi) in order to increase the boiling point of the system.


And what happens when the boiling point is exceeded? Yeah, it's a mess.

I'm not interested in experiencing this on a hot summer day in a bad traffic jam. And I haven't had to in any of my Fieros... thanks in part to swapping out the factory fan switch.

 
quote
Originally posted by thesameguy:

Circumventing or modifying systems because of the way you feel and not because there is an engineering reason to do it is just wasting money - and in this case maybe wasting gas and wasting the air we all breathe and actually putting unnecessary stress on components like the fan and catalytic converter.


What part of the following do you not understand?

 
quote
Originally posted by Patrick:

When any of my Fieros are being driven, even on hot summer days, Rodney's 210° on and 200° off fan switch never turns the fan on while the car is moving.

Please explain how this switch contributes to lowering the operating temperature of my engine when it doesn't even do anything while the car is actually being driven?


If this fan switch does NOT turn on the fan while I'm driving, how is it "wasting gas and wasting the air we all breathe and actually putting unnecessary stress on components like the fan and catalytic converter"? You continue to ignore what I've stated.

[This message has been edited by Patrick (edited 03-24-2015).]

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Report this Post03-24-2015 10:37 AM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:And what happens when the boiling point is exceeded? Yeah, it's a mess.

I'm not interested in experiencing this on a hot summer day in a bad traffic jam. And I haven't had to in any of my Fieros... thanks in part to swapping out the factory fan switch.


I do not know what the struggle here is - I don't know why you keep making up science to justify what you've done. The boiling point of a properly maintained cooling system is about 262 degrees F. That is the boiling point of water, plus a 50/50 mix, plus the pressure from the radiator cap. If you have reached 262 degrees everything has already gone wrong. You are almost 30 degrees past the factory fan switch. The needle is buried in the red. If things have failed to the point you are here, you're doing it wrong. You will not boil the cooling system no matter what fan switch is installed, period.

 
quote
Originally posted by Patrick:

If this fan switch does NOT turn on the fan while I'm driving, how is it "wasting gas and wasting the air we all breathe and actually putting unnecessary stress on components like the fan and catalytic converter"? You continue to ignore what I've stated.



Does your car not use gas or produce exhaust while it's idling? Mine does, but maybe yours is different. I have no immediate explanation for that.

[This message has been edited by thesameguy (edited 03-24-2015).]

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Report this Post03-24-2015 10:52 AM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
I'll say one thing , it does seem we are learning to remain civil during these online exchanges.
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Report this Post03-24-2015 11:33 AM Click Here to See the Profile for David HambletonClick Here to Email David HambletonSend a Private Message to David HambletonEdit/Delete MessageReply w/QuoteDirect Link to This Post
All of the discussion about the technical points is missing the point. The 'warmed-up' temperature shown during normal non-stop driving is fairly steady and well away from the red zone.

Fiero gauges show a significant increase in coolant temperature over the normal driving temperature before the fan kicks in to cool things back down to the temperature shown during normal non-stop driving.

Are people aware of any other vehicles where the temperature gauge goes up close to the red zone before the fan turns on? I've not seen it anywhere but on my Fieros. ('84 SE, '86 2.5L & '88 Formula).
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Report this Post03-24-2015 12:07 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
No point has been missed. The exact same things have been repeated over and over again. It doesn't matter if the temperature goes up and down as long as it stays in the normal operating window which is 195 degrees to 235 degrees. Thermostat to fan switch, minimum to maximum. Everything within that window is fine. The engine can take it, the coolant can take it, all the pieces involved can take it. It's normal. It's the reason why the middle of the gauge is normal and only the end is red. If 235 degrees was a problem, 235 degrees would be red instead of 260. My motorhome - with a GM chassis and 454 and a 235 degree fan switch - behaves in exactly the same way when it's stressed. Any of the dozens of other GM cars - from Cadillacs to Oldsmobiles - with 235 degree fan switches will behave in the same way. It is because the thermostat controls the minimum temp and the fan switch controls the maximum temp. Any engine not otherwise cooled (by arctic ambient air or sufficient air flow) will always ultimately bounce off the fan switch temp. Since you can't control the ambient air and active shutters weren't popular back in the '80s to control airflow, sometimes the engine runs at less than optimal temperatures. On cold winter mornings, sometimes my Fiero never even gets to 200 degrees. It is why you see big semis with covers over their grilles in cold weather - it helps them warm up and save fuel. That is the nature of the beast, the tolerance built into the system. It's fine. As Dobey also pointed out, the nature of the Fiero's cooling system - with long pipes, an insulated engine, and a significant volume - results in temperature swings you might not see on other cars. It's normal and expected. It is how it is supposed to work.

The hilarity of this conversation is that my friend - a GM engineer for many years (now with Lockheed) - once told me that on the newer GM cars the gauge is run by the computer so that the middle of the gauge represents 80% of the engine's variance, with 10% for the left side and 10% for the right side of the gauge. They did this - isolated the gauge from the sensor - because people would come in and complain the needle wasn't right in the middle and they were sure something was broken. Trying to explain "it's only broken if the needle is in the red" would result in customers arguing. That is literally what it happening here. The "oh no, it's right of center [but not in the red]" people are complaining about the system being broken. It's not. It's fine. And it's been fine for bazillions of GM cars before someone started selling GNX and Corvette fan switches for 60* V6s. If 235 was the danger zone, it'd be red, and you can be fairly certain GM wouldn't give a 1 degree safety margin. That is not, typically what GM does. Do you also shift at 3000rpm to avoid approaching the red zone at the end of the tach? Change your brake pads at 1/2 worn to avoid approaching the wear indicators? Come on people, this is not rocket science. This is '70s-era car stuff at *worst*.
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Report this Post03-24-2015 12:57 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by thesameguy:

Does your car not use gas or produce exhaust while it's idling? Mine does, but maybe yours is different. I have no immediate explanation for that.


You now seem to be suggesting that the rad fan kicks on as soon as any of my Fieros stop moving forward while being driven. Another swing and a miss. Depending on the ambient temperature, it can take quite awhile to occur. This time of year, the fan won't come on at all, even after sitting idling for a considerable length of time. (Correction: I crossed the border on Saturday, and the fan eventually kicked on after 20 minutes in the lineup.) You're arguing against the use of a fan switch that you have no real world experience with.

No kittens or puppy dogs have choked to death due to the use of this switch.

 
quote
Originally posted by 2.5:

I'll say one thing , it does seem we are learning to remain civil during these online exchanges.


Yeah, but I gotta laugh. Look at the direction my ratings bar is "trending". Someone's nose is out of joint that I dare express my experiences with my own cars.

-------------------------------------

[This message has been edited by Patrick (edited 03-24-2015).]

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