I was driving home from work on Friday and realized that my water temperature gauge (which has never worked previously) was spiked into the red. I then noticed that my voltage was very low and figured that I might have thrown the serpentine belt. I pulled over and sure enough the belt was gone. I replaced the serpentine belt (and the A/C belt while I was at it) and started the car back up. I noticed that the temp gauge started climbing and eventually climbed into the red after a few minutes. I shut the car down and checked the thermostat housing. The thermostat was out of place and one of the “arms” was bent and preventing it from laying in place properly. Also the tube on the outlet was bone dry and when opening the radiator cap I couldn’t see any fluid in the radiator.

Is it possible that I could have lost coolant somehow when the car ran hot the other day? I didn’t see any leaks or puddles when I stopped.

I’m going to put in a new thermostat and add some more coolant today and add a few ounces of Water Wetter to be safe. Any recommendations on thermostat temperature and coolant type?

I think the reason my temp gauge appeared to not be working before was that the thermostat was out of place and always allowing coolant to flow through to the radiator. Thus even on long drives the temperature never climbed above about 120 and led me to believe the gauge or sensor was bad.

quote Originally posted by Meatstick62: I think the reason my temp gauge appeared to not be working before was that the thermostat was out of place and always allowing coolant to flow through to the radiator. Thus even on long drives the temperature never climbed above about 120 and led me to believe the gauge or sensor was bad.

This kinda sounds like you've always been leaking a bit of coolant (maybe due to thermostat not being installed correctly) but never noticed. With coolant always flowing, your temp gauge stayed low. At one point when coolant level got too low, the engine overheated and temp gauge started "working"

As far as Thermostat temp, do you drive your Fiero in the winter? If so, I'd keep the 195F (generates more heat).
If you only drive in the summer, you could go with a 180F, which will keep the engine cooler, but will slightly decrease fuel efficiency.

More info in the Ogre's Cave, PowerTrain/Cooling section.: http://home.comcast.net/~fierocave/

------------------
--
Ben
87 GT
84 Indy #1863

[This message has been edited by benoitmalenfant (edited 08-13-2012).]

Thanks, I'll check out the cave.

I got the car in February and plan on driving all winter so I guess I'll stick withe the OEM spec t-stat.

Does anyone have a picture of an OEM coolant tank in the original location? I think I may have a junkyard part that was used to replace the OEM one. I wonder if the leak occurred there by chance.

Are you sure your water pump is working? Although i've never personally seen one, apparently there are some water pumps with plastic impellers floating around out there that aren't strong enough for the Fiero's cooling system, leading to a failed impeller.

I'd strongly recommend a 195 F thermostat...the engine was designed to run that way and running anything lower will just increase the temperature range the engine experiences during driving. As soon as you sit in traffic, the temperature will climb until the fan switch activates at 235 F. The thermostat just controls the lower range of the engine temperature; the fan switch controls the upper range.

Well I think the overheating issue last week was due solely to the serpentine belt breaking. I'm not sure if that would have caused the pump to fail- I'd think the pump would have just windmilled and slowly come to a stop.

I don't think I have the proper coolant tank so I can't use that to determine if I have enough coolant in the system. If I did have enough, would removing both the rad and t-stat cap at the same time result in spillage? I took both off and couldn't see any fluid in either location (both did look wet though).

Do not use any Water Wetter to cool the engine. I have personally ran test with dozens of thermocouples inserted into cylinder heads and blocks and Water Wetter actually decreases heat transfer which allows the coolant to be cooler since it is not removing the heat from the metal. I have seen increases of over 10 Deg_F metal temperature. Further more after removing the Water Wetter the metal temps never returned to normal. After disassembling the engine a slick coating was found on all walls that coolant touched. After seeing that I will never run the stuff in my car. If you are looking for some more cooling run 60/40 H20/Glycol that will lower the temps some and still leave reasonable freeze protection.

Very interesting. I always ran Water Wetter in my racecar per the recommendation of a few guys at the track. I never did any testing with it to measure its effect on coolant temps, much less metal temperatures.

quote Originally posted by masospaghetti: Are you sure your water pump is working? Although i've never personally seen one, apparently there are some water pumps with plastic impellers floating around out there that aren't strong enough for the Fiero's cooling system, leading to a failed impeller. I'd strongly recommend a 195 F thermostat...the engine was designed to run that way and running anything lower will just increase the temperature range the engine experiences during driving. As soon as you sit in traffic, the temperature will climb until the fan switch activates at 235 F. The thermostat just controls the lower range of the engine temperature; the fan switch controls the upper range.

Good point.

------------------
--
Ben
87 GT
84 Indy #1863

After topping off the system and installing a 195 deg thermostat the car ran well for a few days. The temperature gauge would climb to 220 and hold steady. Occasionally on hot days it would climb to 235 when stationary and then the fans would kick on and all would be okay.

HOWEVER, last week I was driving in about 97 deg weather and the car started to overheat (while moving continuously). I started feeling the hoses and pipes leading to the radiator and the thermostat outlet pipe was very hot as was the aft part of the hard piping underneath the car on the passenger side. Somewhere near the middle of that hard pipe was a dramatic temperature gradient that went from very warm to practically ambient temperature in the span of about 4". I pulled the thermostat and it was covered with a fine rust-colored dust. I'm thinking that there may be a blockage in that pipe preventing the coolant from being pumped to the radiator. What might have caused the blockage and what could that particulate be from? I'm going to try to flush the system per the repair manual and see what results that yields.

[This message has been edited by Meatstick62 (edited 08-26-2012).]

Here's the coolant jug in the right place. I'd be surprised if there is one that fits in there that isn't OEM. There isn't really a lot of room and the curves of the frame, the angle of the rad and the proximity of the headlight would make it difficult to fit anything else in there (Trust me, I tried before finally finding one at a bone yard)

[This message has been edited by NetCam (edited 08-26-2012).]

well mine is definitely not the correct one. Mine is practically cubic, I'm going to get a proper tank while I'm at it.

I picked up a Dorman 'universal' coolant tank when I ruined my original one and spent about 10 minutes thinking about how to make it fit before hopping on my bike and getting the proper one. I definitely recommend getting the stock jug as anything else probably doesn't have anywhere near the correct capacity.

I had a similar problem to this and found my thermostat had been removed. In my case i had a cracked coolant pipe on the back of the engine block and a leaking head gasket.

Rust in the system usually means an imbalance of water to coolant. Flush and fill per the caves instructions after getting the correct recovery tank. Might want to get a new radiator cap as well. Those are often replaced with the wrong type.

With the temps being higher than normal here all summer, I noticed a few of my cars run quite a bit hotter than they would normally. Near 100* may be enough to cause overheating that normally wouldnt. If you change the thermostat, you should also change the fan control switch. Most of my cars run a 160* stat, and if they have an electric fan, i put a 175* fan switch in. I never have problems overheating and plenty of heat for winter since I drive all my cars year round up here in Columbus.

quote Originally posted by rogergarrison: With the temps being higher than normal here all summer, I noticed a few of my cars run quite a bit hotter than they would normally. Near 100* may be enough to cause overheating that normally wouldnt. If you change the thermostat, you should also change the fan control switch. Most of my cars run a 160* stat, and if they have an electric fan, i put a 175* fan switch in. I never have problems overheating and plenty of heat for winter since I drive all my cars year round up here in Columbus.

I think I may do that. Do you have a part number or source for the lower temp switch? I see a few listed on Autozone's website but the 2 Duralast options don't mention the triggering temperatures and the 176 degree switch they do have (by Hypertech?) is $52.

quote Originally posted by Meatstick62: The thermostat was out of place and one of the “arms” was bent and preventing it from laying in place properly.

I know all about That.

From my experiences with both the duke and the 2.8...

Spend a couple extra dollars and get this superior 195º thermostat - Stant SuperStat 45819.

And then get Rodney's 210° on and 200° off fan switch to use with it.

If the rest of your cooling system is up to snuff (including the proper overflow tank), you'll no longer have any Fiero cooling issues.

[This message has been edited by Patrick (edited 08-27-2012).]

Whatever temp you chose, get them from Rodney. No problems ever with any of mine.

quote Originally posted by benoitmalenfant: As far as Thermostat temp, do you drive your Fiero in the winter? If so, I'd keep the 195F (generates more heat). If you only drive in the summer, you could go with a 180F, which will keep the engine cooler, but will slightly decrease fuel efficiency.

This is a common misconseptiopn. A cooler thermostat will keep the engine cooler in the winter, not in the summer heat. Once the thermostat is open, no matter the temp of the thermostat it is open. So on a hot day if the car wants to run at 200 degrees plus, the thermostat will not make it run cooler. Cooler hermoatats do hurt engine life, since in the engine des not get as hot to "boil" the moisture out of the oil.

You could try out a 3 core aluminum radiator... https://www.fiero.nl/forum/Forum2/HTML/098899.html

http://www.ebay.com/sch/i.h...mpion+radiato&_rdc=1

I bought one for my 3800sc swap. I may get around to installing it all someday...

------------------
-Brian

My 87 GT Poly Suspension Upgrade (all pics) thread
Removing the roof panel

OE and many V6 swaps is fine on 1 or 2 "cores" of radiator. (I think most replacements are 2 cores.)
Problem is:
Many times car has crush pipe(s) and/or bad hoses.
Run w/ weak coolant and radiator is block by corrosion. Usually Flushing will not help.
Has wrong rad cap.
Overflow tank or plumbing to it leaks air when rad is trying to suck in coolant.
Car is missing body panels.

Smaller coolant tank is not a problem but any small leak will drain it faster. GM was a bit to generous in the tank volume and resulting weight will break the mount tabs. Smaller tank then keep a eye out after doing anything requires you to opening the coolant system.

"3 core"
In fact 3 core isn't 3 time better at cooling and even can cause some problems but I'm too tired to play Mythbuster...

In short story...
Any radiator can cool to cold and Tstat has to play catch up trying to make temp and engine stable. Superstat is much better at dealing but over cooling can still be an issue. Lower Weather temp, the faster Tstat will open/close but bigger radiator means Tstat will be in overdrive to warm up the engine.
And what many people sees engine temp raises/lowers as rad fan on/off cycle can be really be Tstat open/shut cycles. Getting coolant temp stable can take a few minute or much longer to never when weather temp too low or use too big radiator. Running Stant SuperStat will help the "problem."

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

Can definitely confirm the tabs breaking from the weight of the jug/coolant. The top tab was broken off mine before I replaced it. The PO had put an oversized washer on to keep it in place, I decided to leave it there to help spread the load.

quote Originally posted by Electrathon: This is a common misconseptiopn. A cooler thermostat will keep the engine cooler in the winter, not in the summer heat. Once the thermostat is open, no matter the temp of the thermostat it is open. So on a hot day if the car wants to run at 200 degrees plus, the thermostat will not make it run cooler. Cooler hermoatats do hurt engine life, since in the engine des not get as hot to "boil" the moisture out of the oil.

That may be the way its 'supposed' to work, but everything dont work as engineered. I had several cars that would run hot in the summer, and the 160* stats stopped that on all of them. Might just be you got to full open flow sooner to prevent it from getting hot in the first place. One of my Fieros ran over 225* in the summer heat. With the 160* and the 175* fan switch, the fan rarely if ever came on at all unless the AC was running. I never seen it get over 200* ever. I only even saw that once stuck in a traffic jam for over an hour at 95*+. I also had heat for floor and defroster within a few miles, even when it was 10* out in winter. Heat kills more engines than cold. The only benefit Ive seen to running hotter, is to get better fuel mileage (and i have my doubts about that)...not for engine life. When was the last time you heard someone blew up their cold engine. The engine dont have to 'boil' out moisture in the oil, any heat will evaporate it out. You can dry a wet piece of metal by blowing your breath on it. Hang a soaked towel out in the yard and see how quick it dries without it having to be 212* out.

quote Heat kills more engines than cold. The only benefit Ive seen to running hotter, is to get better fuel mileage (and i have my doubts about that)...not for engine life. When was the last time you heard someone blew up their cold engine.

A hotter engine will definitely give better fuel mileage, simple thermodynamics show that. Just think about it - a hotter engine means less heat was lost through the radiator, heat that was generated by consuming fuel. Also a hotter engine atomizes fuel better for more complete combustion. While a cold engine won't "blow up", cold oil, larger tolerances, and excessive moisture in the oil will cause the engine to wear faster.

Well after flushing and filling per the Ogre's instructions we've made some progress but it's still overheating. Instead of immediately overheating the car will now take about 4 or 5 minutes to reach 220 but will continue to climb into the red after a few additional minutes. After shutting the engine down with the needle in the red the thermostat outlet is VERY hot, the upper radiator hose is warm, and the lower radiator hose is cool. I'm not sure if this is indicating a slow to open thermostat (it's a new t-stat so I'd assume it is working correctly but have yet to check it in a pot of water) or a water pump that may have failed somehow when the car first overheated a few weeks ago. There was some gray looking debris on the t-stat when we pulled it out of the housing and it washed off. If I didn't know any better, I'd say it looks like gray RTV chunks. Does this sound like a bad water pump to anyone?

[This message has been edited by Meatstick62 (edited 09-06-2012).]

quote Originally posted by Meatstick62: Well after flushing and filling per the Ogre's instructions we've made some progress but it's still overheating ...it's a new t-stat so I'd assume it is working correctly but have yet to check it in a pot of water

Try temporarily running it without a thermostat and see what happens. Despite what you've posted about following Ogre's instructions, it's also possible you just haven't "burped" the system properly.

I forgot to mention that we're going to try running without the t-stat and see if it still heats up that fast.

Do you have any tips on ensuring a good burp?

Here's what I did.

Fill from the thermostat cap with the radiator cap open. Once liquid is seen in the radiator, put the cap on but leave it cracked open just a bit. Fill it up more to push the remaining air out of the radiator, and close the radiator cap.

Then, remove your washer reservoir to access the heater hoses entering your heater core. Loosen the top hose and slip it off just slightly, letting any trapped air out. Once liquid flows out of the top hose, reconnect it. Now you should have no air in the system.

quote Originally posted by Meatstick62: Do you have any tips on ensuring a good burp?

This has been covered a hundred times, but...

* Make sure rad cap is the proper one for Fiero use. The catalogs are wrong! You want a non-vented one,
* Check that the overflow tank and the small hose to the rad are both in good shape. Otherwise air gets sucked in.
* Ensure that coolant level in overflow tank is at the "Cold" level.
* Position rear end of Fiero higher than the front.
* Remove thermostat housing cap and thermostat... and then add coolant to thermostat housing with rad cap also removed until coolant runs out the top of the radiator.
* Re-install rad cap.

* Continue to add coolant until you see the level come up to where the thermostat normally sits.
* Put thermostat cap on and turn just barely enough to hold cap on.
* Start engine and run for about 30 seconds.
* Remove thermostat cap and check coolant level.
* Repeat last four steps until coolant level no longer drops.

* Re-install thermostat and thermostat housing cap.

As long as there are no blockages anywhere in the cooling system and the water pump is circulating coolant, you should be good to go.

[This message has been edited by Patrick (edited 11-08-2014).]

Your description really sounds like either blocked flow (crushed pipe, dirty radiator core) or a plastic impeller water pump that is slipping.

So after burping the system and adding about a gallon of coolant the car ran well for about a half hour without overheating. That was with the thermostat out. During a half hour drive last night the car took 20 minutes or so to get up to temperature and wouldn’t get above 230 or so before dropping back to around 210. This morning it never got about 140 or so on a 10 minute drive. I’m not sure if the water pump is bad if it is still running cool with the tstat removed. We’ll try putting the tstat back in today and see if the overheating problem returns. If it does I think that the tstat will be my prime suspect.

A t-stat that doesn't open fully is a blockage too.....

yep, I guess it is. I hope it's just a problem with an $8 part that's easy to replace, rather than something else.

quote Originally posted by Meatstick62: I hope it's just a problem with an $8 part that's easy to replace, rather than something else.

I take it then that you didn't follow my advice?

quote Originally posted by Patrick: Spend a couple extra dollars and get this superior 195º thermostat - Stant SuperStat 45819.

Having said that, don't assume that the thermostat itself was to blame for the overheating. I suspect you still had a large pocket of air in the system.

[This message has been edited by Patrick (edited 09-07-2012).]

quote Originally posted by Patrick: Having said that, don't assume that the thermostat itself was to blame for the overheating. I suspect you still had a large pocket of air in the system.

Yeah I very well could have. I still don't have the correct coolant tank so I don't know what my coolant level is precisely at but the car did take another gallon of water yesterday. I guess that means there could have been a gallon's worth of air in the system.

I already had a Duralast 195 degree tstat in there. If that one proves to be bad, I'll get the Stant!

Regular Prestone green coolant + distilled water. If you're feeling particularly lazy use Prestone 50/50 mix. Do not use Dex Cool.

I dont get buying a 50/50 premix antifreeze. Its the same cost for a gallon of unmixed. Just keep an old milk jug and make your own 50/50 mix.

You could also be having a lower radiator hose collapsing from age. If it gets a vacumm, the hose sucks shut restricting the flow. In the old days, we put a big wire spring inside the hose and reinstalled it. The hose then CANT collapse.

Ok, good news- the car doesn't overheat with the tstat in. The wierd part is that it seems to be running too cold. After a 30-45 minute drive, it never reached operating temp and never stayed above 180 for long. On the highway or at any decent speed the temps would fall below 160 degrees and never go higher. Also, the cabin feels very warm. My a/c has never worked, but even with the windows down it still feels very warm inside the cabin. Could there be a problem with the heater core that is diverting a good chunk of the engine's heat into the cabin? I think I may have an exhaust leak from the firewall-side header but not enough to cook the cabin though. Any thoughts on the low coolant temps and high cabin temps?