My Fiero has begun to overheat again, for no apparent reason, key word here is apparent.
This has been an on and off, ongoing problem since the engine swap was completed.

The set up is Chevy 350 crate engine with vortec heads (Part No. 1246041)
TPI from an 89 Camaro, 36 lb Injectors, a high performance intake manifold from street and performance, remote mounted electric water pump (Proform part NO. 66225BK), large cap HEI distributor, 4T60 transmission (not electronically controlled) w/adaptor plate from V8 Archie’s, 4 core radiator also from V8 Archie’s.
Cardomain page http://www.cardomain.com/ride/2619515
Build pictures http://s920.photobucket.com...ine/87%20GT%20Build/
I did not do a build thread here on Pennock’s

The car has only been driven about 1500 miles after the swap so the parts are virtually new except for the distributor. I do not think a worn distributor could cause this problem but I could be wrong, please correct me if I am.

I have done the following things to try to fix this problem:
Checked and changed thermostat twice. I have tried a 180 and a 195 degree (it has vent holes to purge air)
Purged air out of system or lack thereof 6 times
Checked coolant tubes no defects or leaks
Changed radiator and filler neck caps twice
There is no blockage as the coolant is moving at a good rate through the system
Checked water pump (electric pump appears to be working correctly)
This is the water pump I have http://www.proformparts.com...e/Wcb446fc02a782.htm

I am starting to think that maybe the coolant is moving too fast and not spending enough time in the radiator. I am going to check the heat difference between the inlet area of the radiator and the exit to see if fluid entering the radiator is hotter than the fluid leaving the radiator if there is not a reasonable difference I will know the coolant is not staying in the radiator long enough. I would like to check the flow rate but I am not sure what it should be, Maybe Archie knows as he is using electric pumps now. I will ask him if he does not post in this thread.

The car will run fine and heat up at the normal rate, gradually rising until it reaches about 195 degrees this is when the thermostat opens, and this is also the time when it heats up fast to about 230 degrees this is when it starts to boil out of the overflow tank. It appears the opening of the thermostat has the opposite of it intended effect. I think this is a low temperature for the coolant to boil out unless it is boiling at a lower temperature for some reason.

I have consulted everyone I know that is either a mechanic or an engineer, I think some of these ideas are viable and I think some are not but I did learn a few things about fluid dynamics reading about these theories.

A few other theories are:
Cavitation: http://www.mcnallyinstitute.com/09-html/9-10.html
Bernoulli's Principle states that as the speed of a moving fluid increases, the pressure within the fluid decreases. So in the case of coolant in a pressurized system the faster the fluid moves the lower the pressure thus lowering the boiling point. http://home.earthlink.net/~mmc1919/venturi.html

The coolant is moving too slow.

The worn distributor is throwing the timing off causing a lean condition.

My Fiero is cursed, or it just hates me.

Boiling point info:
http://www.engineeringtoolb...int-water-d_926.html

If you have any other ideas or suggestions, I would love to hear them,

Thanks,
Christine

My first thought was that it was running lean, since you've checked the cooling system as thoroughly as you have.

At least, I did, until I read down farther where it sounds like the coolant temperature suddenly shoots up to boiling when the thermostat opens. That makes me think that the coolant at the temperature sender & the thermostat isn't as hot as the coolant that's actually inside the block. By the time the coolant at the thermostat gets to 195 degrees, the coolant in the block is already at 230 degrees; the thermostat finally opens enough to let the coolant circulate up to the radiator and as soon as it does, the coolant flowing past it and the sensor is the 230 degree/boiling coolant from in the block. It hits the radiator and quickly makes it overflow.

In other words, by this theory, your thermostat is acting as a blockage in the system. Why? Because, for whatever reason, the coolant at the thermostat isn't heating up as fast as the coolant in the block. I would think that would mean the coolant is not circulating up to the thermostat, therefore the thermostat isn't at the same temperature as the rest of the coolant/engine.

The only thing that comes to mind is something to do with the electric pump circulating the coolant differently - or not at all! - compared to a belt-driven pump, and it isn't circulating coolant up to the thermostat. At least not until the thermostat opens. Once it's open a crack and lets even a little bit of coolant past it, it would get up to temperature with the rest of the engine/coolant really quick. So unless there's some kind of bypass to let at least a little bit of coolant circulate past it (and warm it up at the same rate as the rest of the coolant), it's just going to sit there and remain closed until it finally gets heated up enough.

The easy way, in my opinion, to test this would be to simply remove the thermostat from the equation. It'll take a lot longer for it to warm up, yes, and may never get up to temperature if it's being driven, but if you let it idle or otherwise get up to temperature while it remains stationary, you should find out soon enough if my theory is correct. If it still overheats, I'm way off. If it gets to the point that the rad fan turns on and you let it keep running for a bit and it still doesn't boil over, then you've found the problem.

If that works, then now you need an actual solution.
Perhaps the thermostat is in upside down? that would take it forever to open up, I would think.
Perhaps it's the wrong thermostat, even if it's the right temperature. If they even make thermostats with bypasses on them (so they always flow a little bit), and yours doesn't have one, that would probably fix it.
If they don't make such things (I've never thought to ask, I've always just gone up to the parts counter and asked for the right thermostat for my application), I'd be tempted to modify one by drilling a small hole in it (say, 1/4") to allow some flow, and test it that way. Worst it could do, in my opinion, is ruin a $10 thermostat.
Point being: if you can get the thermostat to warm up as fast as the rest of the engine/coolant, it'll open up at the right time and allow the coolant to flow to the radiator to cool it down.

The other culprit that comes to mind if the electric water pump. Could the wires be hooked up backwards, so it's pumping the water in the wrong direction, therefore not letting hot coolant circulate up to the thermostat? Could it be hooked up properly, but meant to circulate it the other way for some reason? could it not be circulating AT ALL on some occasions, therefore making your engine overheat?

I'm sure someone with actual experience with V8s, electric water pumps and what have you will chime in. My experience is limited to the engines I've worked on, but I can usually think/diagnose a problem well enough, whatever the application.

Good luck!

I too have a SBC with TPI in my 308 kit. From the info you've posted it's not clear that there's problem... here's why:

1. First, it doesn't sound like your coolant is "boiling over" nor your engine over-heating. Remember that the coolant fan switch is set to turn the fan on at 235*F. That means that normal operating temperature for the engine is between 195*F (the temperature the thermostat opens) and 235*F (the temperature the fan kicks in). If your coolant is truely boiling over between these temperatures, then you haven't got the correct mixture of coolant to water ratio in your system. Keep in mind too that the temperature warning light only comes on at 257*F. It should come on before your coolant boils over.

2. Second, it sounds like your coolant system is overfilled or perhaps your reservoir isn't large enough. The SBC holds considerably more coolant in the block than the Fiero V6. As it heats, it expands and the pressure increases. Once the pressure reaches the radiator cap pressure rating, the cap opens and allows coolant to flow into the reservoir. I found when I first started my SBC that I overfilled the system in relation to the capacity of the reservoir. I let it overflow from the reservoir until it finally reached a happy medium where the cold volume was acceptable, and near the top of the reservoir when hot. You can also change out the reservoir for one that's bigger. Don't, however, leave the reservoir empty thinking that it'll give you more room for expansion. If you do, then later on when the coolant is contracting after a long drive there's a risk of pulling air into the system if there isn't enough coolant in the reservoir.

Hope this helps.

My V8 isn't running a thermostat. I know its suppose to be bad but hear me out its ran that way for years without any issues.

I have a 350 bored 60 over with a carb. Electric water pump and no heater core hooked up. I can maintain 190 on the hottest day with the radiator fan running. If I get on it I have gotten up to 210 but as soon as I get back off it will come back down to the 190.

A couple of weeks ago I was playing with my timing and it started overheating on me. Put the timing back and it back to normal.

I run a stock radiator out of an 86 SE that had a 2.8 in it. I also run the highest PSI radiator cap I could find. I heard that you should run as high a PSI cap as your system will maintain. I don't remember what it is but I think its 27 PSI

So check your timing and see what your radiator caps PSI rating is and if your still using the 15 PSI try something a little higher. Make sure its non-vented.

I would like some additional information to help narrow this down.

**Are you running the 7730 ecm?
**So is the fan switch stock (235 degrees), are you running a lower temp one, or allowing the 7730 to kick on the fan based on its settings (the there is a max speed setting in the 7730 where the fans will not operate above - like 35 mph and it will rely on only car movement to push air through the radiator).
**Are there some close up pics showing the top and sides of the radiator - if it is not properly sealed, then at speed air can be pushed around vs. through and will hurt cooling efficiency at speed.
**With the 4 tapped holes along side the thermostat housing, I assume all temp switches/senders and heater core supply line are in that location and not in the side of the heads. Correct?
**Is the heater core hooked up? This is the bypass loop when the thermostat is closed and needs to be hooked up? Ideally the heater core supply should be in close proximity to the thermostat to help move any potential air pocket from this area when the thermostat is closed. Sometimes on the later cars (87/88), the heater core circuit is too good (very low restriction) and will keep a good portion of the coolant from going through the radiator. Once the car is warmed up, pinch one of the heater core lines up front (probably easiest place to access) and then go for a dirve. If this helps the car run cooler, you should install an inline restrictor (put something in the hose to restrict it down to 1/4" diameter hole). This will ensure the majority of the coolant goes through the radiator, but still keeps the heater core hot enough for mild winter driving.


If you have a non-contact infered thermometer... they are quite handy at figuring out that the tempature deltas are at each transition within the coolant system.

Looking at your pictures I could not see a deflector under the radiator.If you don't have that,the car will operate normally at low speed and overheat at highway speeds.The deflector is needed at higher speeds to direct air up to the radiator.

------------------
#1112
Question my ability,question my intelligence,never question my integrity!
87drivetrain http://fieroaddiction.com/SBCTa.html

quote Originally posted by Jake_Dragon: My V8 isn't running a thermostat. I heard that you should run as high a PSI cap as your system will maintain. I don't remember what it is but I think its 27 PSI

I don't mean to rain on Jake's parade, but you should take his advice only after considering the following:

1. The thermostat technically isn't needed but if you run without one, your fuel economy will suffer. The T-stat is designed to bring and hold the engine to it's optimum operating temperature quickly. If you run without one, your engine will take longer to warm up causing you two further problems you won't notice for a while. The first is that you will run with tighter internal clearances causing more friction on moving parts for a longer period of time after start up. The second is that your oil will remain thicker as it takes longer to heat up to it's proper operating temperature too. Thicker oil doesn't pump or lubricate as well as oil at the correct temperature. There is no good reason to run an engine without a thermostat.

2. Your radiator cap should be rated for whatever Archie recommended for the radiator, no higher. Keep in mind that the stock Fiero cap is 15 PSI for two reasons. The first is that 15 psi raises the boiling point of a 50/50 mixture to 262*F... which is great because it's 5*F higher than the temperature that the light turns on. The second is 15 psi ensures the cap will relieve the pressure before the radiator ruptures. The cap is the pressure relief valve designed to protect the radiator from blowing a cooling vane since it's the weakest link in the system. You might think you're OK to run a higher pressure rad cap because " it's worked well for years", but all it takes is for you not to notice an engine over-temperature condition once, and you will be replacing more than just boiled-over coolant. The other thing is that even though you may not have noticed any problems, as long as the pressure remains below the rupture pressure of the rad and the opening pressure of the cap, this potentially allows your engine to run hotter than it was designed for. If this happens, it will result in clearances that are too large for optimal piston sealing and bearing lubrication. Over the medium term, you can rest assured you'll be rebuilding the engine sooner than if you just let the system run properly.

The aim here isn't just to keep the coolant from blowing... anyone can jury-rig a coolant system to do that. Instead, you'd be better off to find out the cause of the problem and correct it, then allow the sytem to work as it was designed, ie to keep the operating temps between 195*F and 235*F.

Just use a temperature switch on the water pump to control the temperature instead of a mechanical restriction. The car will come up to the proper temperature and you will reduce the wear on your water pump.

Granted the Fiero radiator wasn't made for those pressures but thats why I have the aluminum replacement that will get installed when I finish some of the other projects. (it came with the higher PSI cap I stole it and installed it on my current setup) I cant find the article that made me go with the bigger cap right now but it made me change after I read it. Made sense at the time as the higher pressure does change the boiling point and should reduce steam pockets. But be aware that your heater may not like running at the higher PSI, I don't know as I don't currently have a heater installed.

I run my fan from a switch currently, so far it hasn't seen 220 one time with this setup. But I would rather not depend on my memory. I have the temperature switch on my bench, here in Florida I almost never have an issue with it not getting up to temperature quick enough I have the timing adjusted until it runs in the correct temp range and read the spark plugs to make sure its not lean or too rich, it warms up as fast as my Vette with a thermostat installed. The plan is to install the fan switch in the intake and have it come on at 190 and control the radiator. Right now I don't have to run the fan on the trip into work and turn it on as soon as I leave the parking lot on the way home so I don't forget. I was thinking about installing a switch that will turn on the water pump at 160 - 170 and install that in the head but currently it runs all the time.

I don't use a thermostat because of the electric water pump. Because I don't have the heater installed I would be dead heading the water pump until the thermostat opens and I don't think thats a good idea but wouldn't be worried if I had the heater installed to bypass the thermostat.

Thanks Bloozberry I will think about what you posted as I move forward with my projects. I hate parades.

quote Originally posted by Jake_Dragon: Just use a temperature switch on the water pump to control the temperature instead of a mechanical restriction. The car will come up to the proper temperature and you will reduce the wear on your water pump. I don't use a thermostat because of the electric water pump. Because I don't have the heater installed I would be dead heading the water pump until the thermostat opens and I don't think thats a good idea but wouldn't be worried if I had the heater installed to bypass the thermostat.

These are good points. With an electric pump, the need for a thermostat is questionable since you can control the flow of coolant with the pump. I wasn't thinking about that when I posted the above. Thanks for pointing that out Jake.

1 - Moving the coolant slower through the system will decrease the heat transfered from the engine to the radiator - period.

2 - boill over, or coolant expansion - Is the coolant actually boiling over?

3 - Not a solution - but a test - what happens when you run without a thermostat?

4 - Cavation - Unless your moving the coolant at some very high rate of speed cavation is not going to be a problem.

So far, I don't see any mention of the radiator cooling fan. Is it working properly? And if so, at what temperature does it come on? You may want to set it to a lower temperature.

Also, Hugh has a good point about the front air dam. If that piece is missing, your engine can overheat at speed.

[This message has been edited by Blacktree (edited 07-11-2010).]

Does your radiator fan come on (fan relay)?You can allso buy one of those radiator pressure kits to see if your cooling system is holding pressure.If you have a fast Idle,that can cause an over heating problem (a vacume leak or timeing can cause this).Check for water in the oil (milkey Brown),I'de rather run with out a thirmistat,the gas milage isue isnt anything Im concerned with.If you installed an aftermarket radiator fan,there are two types,1.pusher fan-pushing the air farward and a 2.puller fan-pulling the air in and through the radiator.The problem with a fan that pushes air,through the front radiator is that,when you are driveing,the fan is working aginst the air trying to flow through the radiator (possibley you reversed wired the fan).Another little problem is this,the red radiator coolant and the green radiator cool,can NOT be mixed,because it will jell.I know your probubley changed the coolant,but there is still some coolant trapped inside the engine block,by the thirmistat,hopefulley you got all that out (you would probubley see bits of jell stuck to the bottom of the radiator cap or engine thirmistat cap,if thats a problem).Did you wire the electric water pump correctley?A reverse flow would cause problems ........just my 2 cents.

[This message has been edited by James Bond 007 (edited 07-11-2010).]

I'm going to try a restrictor washer in mine...in place of a thermostat... (350 sbc ,elec. pump and msd dist and 6a ign.)

We have very similar setups except yours is so much prettier Taking cam and exhaust aside, you have a different e-pump and radiator. You even are runing a top hose to the water neck which makes taking bubbles out very easy. I would look at those areas (rad, pump) plus making sure the timing is right. Does it also overheats with the A/C on (fan on all times)?
I run the stock 88 V6 radiator/reservoir with a 180 thermostat and fan switch. Car runs around 190 all the time here at FL all year long (5+ yrs). Hottest I got it was like 225 at a traffic jam at Atlanta on a July day going to the 25th anniversary. Yours should run better with that big radiator.

quote Originally posted by Christine: My Fiero has begun to overheat again, for no apparent reason, key word here is apparent. This has been an on and off, ongoing problem since the engine swap was completed. The car will run fine and heat up at the normal rate, gradually rising until it reaches about 195 degrees this is when the thermostat opens, and this is also the time when it heats up fast to about 230 degrees this is when it starts to boil out of the overflow tank. It appears the opening of the thermostat has the opposite of it intended effect. I think this is a low temperature for the coolant to boil out unless it is boiling at a lower temperature for some reason. If you have any other ideas or suggestions, I would love to hear them, Thanks, Christine

Wow, this is a good thread, I don't think I've ever seen a thread that had as many good suggestions made in such a short period of time.

From looking at your picture albums, it looks like you have a great looking & well thought out build. It would have been a great PFF build thread.

I wish you could have communicated about this problem a long time ago, I think we could have given you several years of enjoyment & a lot less frustration.

Early in your post you say it's been an "on and off, ongoing problem" I'm a little confused by that.... if you could elaborate on the conditions it could be helpful.

Can you tell us if it's occuring at Idle speed, or when driving slowly around the neighborhood or if it's doing it at highway speeds or all of the above. Also I'd like to know about your fan & controls for it.

To be honest, if you called on the phone I could ask several questions & get answers & then I could give you a bunch of things to look for. We could likely get thru all of that in about 30 minutes. However to do that in this post would take me 2 hours to type up the same questions & make the same suggestions.

Today just happens to be my birthday & I just can't put 2 hours into typing today.

From looking at the pics, I'd guess that your problem is happening at highway speeds & that it could idle all day long in your garage without having a problem.

The pictures are really helpfull & I do have one question about where you hooked up the Heater core hoses. The large hose feeding into the W/P should be coming from the right side water pipe & The 3/4" heater hose coming from the heater core should connect into this line before the water is sucked into the W/P. The 5/8" Heater hose is water going to the heater core & should connect to the heater hose barb on the front end of the TPI manifold.

Someone pointed out the missing air dam up front. If we were having this conversation on the phone, one of the 1st 3 questions would have been about the air dam & wether you still had the ducting that directs air into the radiator & keeps the air excaping without passing thru the radiator.

I see you also have the front plate on the car, it also can block the air intake into the radiator. That makes the air dam & nose ductwork even more important. In the beautiful phohobucket picture #75, it looks like the nose opening on either side of the license plate is closed in a little at the top of the opening. Kind like the plastic is sagging.

From other pics, it appears that you don't have any ventillation behind the radiator to vent the hot air out from that area so more cool air has a place to go when it come thru the radiator. If your problem is happening at speed, have you tried to pull the hood release to see if the tempurature goes down?

Archie

[This message has been edited by Archie (edited 07-11-2010).]

My 383 crate engine ran a Edelbrock carb, the Archie belt driven 55 chevy water pump, 160* stat, original Fiero 4 cyl radiator, ram horn exhaust manifolds and automatic tranny. Once it was properly burped it never got over about 175* in the summer heat and traffic. I didnt have AC. If theres no problem internally, like leaking head gasket, Im thinking your running too lean or spark is too advanced. Are you positive the radiator is flowing good. I didnt have any problems overheating in the Coronet, but radiator shop tested it because of some small leaks and found it was only flowing about 60% of capacity before they back flushed it out.

I am going to try and answer all the questions everyone has asked starting at the top.

Stubby79,
The thermostat is vented meaning the coolant can pass through it when it is closed and if you look at the filer neck at the high point of my car there is a cap when you remove the cap you can see the coolant racing by when the key is on as the pump can run with just the key on and the car not running.

Boozberry,
The coolant may not technically boiling but it boils out of the tank when the temp rises over 230. The system is not over filled we made sure of that and we made sure the tank did have enough fluid in it for reserve.

Jake_Dragon,
I do not think the thermostat is the problem as plenty of fluid gets past it even when it is closed and the car gets hotter quicker when it is open so I do not think taking it out will help this.

Fieroguru,

1) Are you running the 7730 ECM?
Yes I am.

2) So is the fan switch stock (235 degrees), are you running a lower temp one, or allowing the 7730 to kick on the fan based on its settings (the there is a max speed setting in the 7730 where the fans will not operate above - like 35 mph and it will rely on only car movement to push air through the radiator).

We have the auxiliary fan set to 160 degrees it is on the trans/oil cooler in the back and the main fan is set to come on at 180 this is programmed in to the prom.

3) Are there some close up pics showing the top and sides of the radiator - if it is not properly sealed, then at speed air can be pushed around vs. through and will hurt cooling efficiency at speed.

I have attached some pictures so you can elaborate on this I am not sure I know what you mean.

4) With the 4 tapped holes along side the thermostat housing, I assume all temp switches/senders and heater core supply line are in that location and not in the side of the heads. Correct?
Correct.

5) Is the heater core hooked up?

I think the heater core is hooked up as it was when the car was stock my brother did that part so I am not sure I will check, but I did not think he changed any of that stuff.

This is the bypass loop when the thermostat is closed and needs to be hooked up? Ideally the heater core supply should be in close proximity to the thermostat to help move any potential air pocket from this area when the thermostat is closed. Sometimes on the later cars (87/88), the heater core circuit is too good (very low restriction) and will keep a good portion of the coolant from going through the radiator. Once the car is warmed up, pinch one of the heater core lines up front (probably easiest place to access) and then go for a drive. If this helps the car run cooler, you should install an inline restrictor (put something in the hose to restrict it down to 1/4" diameter hole). This will ensure the majority of the coolant goes through the radiator, but still keeps the heater core hot enough for mild winter driving.

Wouldn’t the coolant not go through the heater core if it were off? Just for information I have tried running the heater while driving to see if it makes a big difference in the overheating. I seem to help a little but not much, it will still get too hot just not as fast.

If you have a non-contact inferred thermometer... they are quite handy at figuring out that the temperature deltas are at each transition within the coolant system.

I do have an inferred thermometer and I am going to take it out tomorrow and get it up to about 210 and then check to see if the inlet side of the radiator is hotter than the outlet area of the radiator. Do you know how much difference in temp it should have when leaving the radiator? For example it is entering at 210 should it be leaving at say 190 or what?

Blacktree,
See number 2 above about the cooling fan.

James Bond 007,
Also see number 2 above, and the fan is pulling as it should be and the pump is flowing the correct direction we did check those things.

Alex4mul,
It is set up to have the A/C put back on it but it is not on the car at this time so it is not affecting it.

Archie,

First of all happy birthday, I would have called but I hate to be a bother, but since you offered if it is ok I will call you tomorrow when it is not your birthday, to discuss this problem.
I will respond to the questions you had for everyone and I will post the outcome when I get it fixed.

1) Wow, this is a good thread, I don't think I've ever seen a thread that had as many good suggestions made in such a short period of time.

I too was surprised at the great response.

2) From looking at your picture albums, it looks like you have a great looking & well thought out build. It would have been a great PFF build thread.

Thank you

3) I wish you could have communicated about this problem a long time ago, I think we could have given you several years of enjoyment & a lot less frustration.

Sorry I just hate to impose too much on people. I will call first next time.

4) Early in your post you say it's been an "on and off, ongoing problem" I'm a little confused by that.... if you could elaborate on the conditions it could be helpful.

ON and OFF, when we first got the car finished we had a hard time getting it tuned right and it ran hot. I finally found a guy that could burn the chip correctly and it then ran cooler then we found it still got too hot on hot days and under a lot of load so we then adjusted the timing and it ran cooler but was still borderline running around 210, which I think is still too hot. I ran it all last summer at the 210 thinking it had leveled off and I was just going to have to live with it. Then I got the car out this spring and it was still running at the 210 until the weather got hotter then so did the car.

5) Can you tell us if it's occurring at idle speed, or when driving slowly around the neighborhood or if it's doing it at highway speeds or all of the above. Also I'd like to know about your fan & controls for it.

The car heats up normally and then at around 195 it starts to heat up faster, it will heat faster under load but if I put around it will still get too hot. I did an experiment and got it up to around 230 just before it starts to come out of the tank, I then parked it in the garage and let it idle. It did not boil out of the tank but started to cool off slightly it when down to about 220 or so than then help at that temperature, but if I start driving it at any speed when it is at 210 or above it overheats.

6) The pictures are really helpful & I do have one question about where you hooked up the Heater core hoses. The large hose feeding into the W/P should be coming from the right side water pipe & The 3/4" heater hose coming from the heater core should connect into this line before the water is sucked into the W/P. The 5/8" Heater hose is water going to the heater core & should connect to the heater hose barb on the front end of the TPI manifold.

I will check how this is hooked up I thought Tom put it together as it was stock but it could be hooked up different.
Does anyone have a picture of how this is supposed to be hooked up, I loaned my Fiero manual to someone and have not gotten it back yet.

7) Someone pointed out the missing air dam up front. If we were having this conversation on the phone, one of the 1st 3 questions would have been about the air dam & wether you still had the ducting that directs air into the radiator & keeps the air excaping without passing thru the radiator.

Air dam is in place and not damaged and functioning. Pictures attached.

8) I see you also have the front plate on the car, it also can block the air intake into the radiator. That makes the air dam & nose ductwork even more important. In the beautiful photobucket picture #75, it looks like the nose opening on either side of the license plate is closed in a little at the top of the opening. Kind like the plastic is sagging.

I was running it without the front plate for a short time and then the paint got damaged so I put on to cover the damage, it did not seem to affect the cooling at the time. I could take it back off to see if it helps though. Yes the plastic is sagging I plan to replace it when I get some money.

9) From other pics, it appears that you don't have any ventilation behind the radiator to vent the hot air out from that area so more cool air has a place to go when it come thru the radiator. If your problem is happening at speed, have you tried to pull the hood release to see if the temperature goes down?

I did try removing the weather stripping and propping the hood up to let the air out, it did not seem to make any difference though.

Rogergarrison,
I could still have a timing or tuning glitch that could be contributing to this problem, the guy that does my tuning and burns the chips is checking the program to see if we can tweak it to get it to run cooler, he will let me know this week.

I forgot who asked about the coolant mixture, it is 50/50

I posted 4 pictures below but there are more here http://s920.photobucket.com...%20cooling%20system/

[This message has been edited by Christine (edited 07-11-2010).]

It looks like your front air dam is intact.

Unfortunately, I can't offer any more suggestions. I'm stumped. I'll wish you luck, though.

You mentioned that at 230*F it starts bubbling over... but again, that doesn't mean the engine is overheating. What it does mean is that the fluid is expanding and is being allowed to flow into the reservoir. The fluid will immediately boil because the Fiero's reservoir isn't pressurized, and at 230*F at atmospheric pressure, it will boil very rapidly.

Actual engine overheating occurs if the engine temp gets into the 240 - 260*F range (and even then, it's more like above 250*F). You haven't yet said that you've seen it past 230*F... which is only in the normal-high range. I still believe that your problem may be a reservoir that's too small especially given that you've got an oversized radiator, and larger than stock engine. But it's hard to tell without actually seeing what's happening first-hand.

If you're convinced otherwise, then here's a few more things to look for:

1. a collapsed upper or lower rubber radiator hose or engine hose when the system is operating. Tthe cold side hoses should have a metal spring on the inside of the hose to keep it from collapsing under the suction of the pump. Older hoses also get softer than newer hoses as they heat up;
2. a faulty rubber seal on the radiator cap (of course to check that, you'll need to jack the front of the car higher than the engine to prevent half your coolant from draining out); and
3. a burred or damaged radiator cap sealing surface inside the radiator (ditto as above).

quote Originally posted by Bloozberry: You mentioned that at 230*F it starts bubbling over... but again, that doesn't mean the engine is overheating. What it does mean is that the fluid is expanding and is being allowed to flow into the reservoir. The fluid will immediately boil because the Fiero's reservoir isn't pressurized, and at 230*F at atmospheric pressure, it will boil very rapidly. Actual engine overheating occurs if the engine temp gets into the 240 - 260*F range (and even then, it's more like above 250*F). You haven't yet said that you've seen it past 230*F... which is only in the normal-high range. I still believe that your problem may be a reservoir that's too small especially given that you've got an oversized radiator, and larger than stock engine. But it's hard to tell without actually seeing what's happening first-hand. If you're convinced otherwise, then here's a few more things to look for: 1. a collapsed upper or lower rubber radiator hose or engine hose when the system is operating. Tthe cold side hoses should have a metal spring on the inside of the hose to keep it from collapsing under the suction of the pump. Older hoses also get softer than newer hoses as they heat up; 2. a faulty rubber seal on the radiator cap (of course to check that, you'll need to jack the front of the car higher than the engine to prevent half your coolant from draining out); and 3. a burred or damaged radiator cap sealing surface inside the radiator (ditto as above).

All I can say about the temp is that is approximately around 230 to 240 my gauge is an Autometer and Is not all that great it has a 210 marker and a 250 marker and one few small line between them so I am kind of guessing at the exact temp when the coolant bubbles out of the tank. The needle is past the small line I think is the 230 mark between the 210 and the 250 mark so your guess is as good as mine is. I have never let it get to the 250 mark I always shut it down before it gets that hot.

I mentioned in my first post that we have replaced the caps just to be sure they were good.

The hot side hose is new, looks, and feels fine when it is hot. The cold or return hose is hard to see but it is braided hose so I do not think it is collapsing but I will check it tomorrow when I get it refilled with coolant and do a few of the suggested tests on it.

The tank is the stock tank and it was working for the last 1,500 miles so I am not sure why it would not work now. I could try a bigger one but there is not much room to use one much bigger, do you know of a bigger on that fits in there?

Temp gauge picture

I know that pressure in the system raises the boiling point, but the OP is in Denver, and I do know that the higher the elevation, the lower the boiling point of water. How this all balances out, I'm not sure, but I live at 4500' elevation, and I do whatever it takes to keep my cars between 200-220. In the summer, I drain the coolant, and refill with straight water, plus 2 bottles of RedLine Water Wetter. Royal Purple's Purple Ice is similar.

quote Originally posted by Christine: ..... We have the auxiliary fan set to 160 degrees it is on the trans/oil cooler in the back and the main fan is set to come on at 180 this is programmed in to the prom....

So the fan goes on off the oil temp? Is the fan coming on between 160-180 on your autometer gage?

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Red: TPI V8 + 6-Speed Yellow: Nitrous 3.4 + 5 speed
304rwHP/366rwTQ

quote Originally posted by Christine: Fieroguru, 5) Is the heater core hooked up? Wouldn’t the coolant not go through the heater core if it were off?

The heater core loop is always open, regardless if the heat is on. All the HVAC system does is allow air to pass over the heater core, but the coolant flows constantly. Once it is up to temp, crimp one of the front heater core lines (this will ensure that all coolant flow is going through the radiator) and see if it gets better.

Have you ever pulled the radiator and cleaned between the radiator and the AC core? Sometimes it can build up debris and restrict flow.

Also, the tranny cooler in front.. it might be restricting the passage of air through the radiator. Might try to take it off and just loop the lines together and take it for a short spin to see what happens.

Once you get done taping the inlet/outlet temps of the engine and radiator, please post them. Those should narrow it down some.

[This message has been edited by fieroguru (edited 07-12-2010).]

quote Originally posted by Alex4mula: So the fan goes on off the oil temp? Is the fan coming on between 160-180 on your autometer gage?

I think the rear fan that comes on at 160 is oil temperature, and the radiator fan that comes on at 180 is coolant temperature.

quote Originally posted by fieroguru: The heater core loop is always open, regardless if the heat is on. All the HVAC system does is allow air to pass over the heater core, but the coolant flows constantly. Once it is up to temp, crimp one of the front heater core lines (this will ensure that all coolant flow is going through the radiator) and see if it gets better. Have you ever pulled the radiator and cleaned between the radiator and the AC core? Sometimes it can build up debris and restrict flow. Also, the tranny cooler in front. It might be restricting the passage of air through the radiator. Might try to take it off and just loop the lines together and take it for a short spin to see what happens. Once you get done taping the inlet/outlet temps of the engine and radiator, please post them. Those should narrow it down some.

I will try crimping the line to the heater core.

The radiator was pulled and replaced with a 4 core when the engine swap was done, basically the whole car has been gone through about 1,500 miles ago. The car is also kept in a garage and never left outside, so getting debris in that area would not be likely in 1,500 miles of driving it.

The transmission cooler is in the back, it is where the air intake used to be on a stock Fiero, the fan is a push fan and is located in the side scoop. I posted the picture in a post farther up but I will post it again so you can see where it is in the car.



I am thinking of adding a surge tank so I do not have to worry about burping the air out in the future.

I will be posting all my findings as I go along.

[This message has been edited by Christine (edited 07-12-2010).]

Sorry if I repeat someone elses response, my eyes are tired. I had a problem like this with my new crate engine. You may have air bubbles in the block. With it being completely empty, you can get air trapped in the block even though you fill the cooling system entirely. Just a process of burping the system over and over till you get them worked out.

quote Originally posted by Turbowedge: Sorry if I repeat someone elses response, my eyes are tired. I had a problem like this with my new crate engine. You may have air bubbles in the block. With it being completely empty, you can get air trapped in the block even though you fill the cooling system entirely. Just a process of burping the system over and over till you get them worked out.

It is possible I still have air in the system. I am going to reroute one of the coolant pipes before I burp the system repeatedly.... Then I will see where I am. 

I have a lot going on besides the car problem so it might take a day or two to get back to everyone with the progress, but I will post to this thread what I do and the results I get.

I always found jacking the back end of the car in the air helped burp mine. Also make sure your heater is on full blast. Ive seen a lot of air pockets made going into or out of the heater core.

quote Originally posted by rogergarrison: Also make sure your heater is on full blast.

Hot water is routed to the heater core regardless whether heat is actually selected. Selecting heat only provides a path for cool air to flow through the heater core, not water.

I spoke to Archie and watched his video; he told me how he would fix it and gave me some pointers on how to fix my car. I am going to try what he said and see if that fixes it. This does involve rerouting some parts of the cooling system, but I think it is the best course of action to take at this point. It will take until Tuesday to get the parts made that I need to fix it. I think I can post the results of the new cooling system route buy Wednesday or Thursday of next week.

Edit: Added link to pictures of existing cooling system set up
http://s920.photobucket.com...%20cooling%20system/

I will add the pictures of the new system as soon as I get it in the car, and the details of what we did and how it works after the changes.

[This message has been edited by Christine (edited 07-14-2010).]

I worked on a lot of SBCs and I might be able to offer some very flawed advice. Will you have your car at the Garden of the Gods Trading Post Saturday? I hope to stop by but I can't drive my car because of fuel pump problems. Besides, it looks just like it came from a field near La Junta. It did.

No, I will not be able to bring it to the Springs this weekend. We think we know what the problem is but it will take a while and I will need to fabricate a few parts to fix it right.

Here is an update for those of you that were watching this thread:
After talking to Archie, I did as he suggested and replaced the radiator fan and I am going to re-route the cooling lines in the back from the thermostat neck to the line going to the radiator on the driver’s side of the car. I had the had 1 1/2” galvanized pipe bent to reroute the coolant line under the engine instead of over it, this will also eliminate the filler tee that I had as it can cause some of my problems.
I had a non-stock fan on the radiator and I found it was not as good as the stock one so I fixed up the stock fan and put it back on the car.
I installed on of the coolant pipes and I am having the other one bent again so it will fit better tomorrow.
After I finish install the new pipes I will refill the system with a 50/50 coolant mix and be sure to get all the air out and then test it out I will post the car performs after I complete the work.





Link to all the pictures http://s920.photobucket.com...ng%20system/?start=0

I gave up on the screw type hose clamps after getting fed up having to go back and check them all the time. I use GM spring clamps on every thing i can.
I have a old, used up 305 crossfire with a 4t60, remote elec w/p, archies rad, 195 thermostat, 15 pound cap, billet thermostat housing with a rad cap on it at the rear. I ran a vent hose from the rear thermo housing to the expantion tank in the front. used a "TEE" to hook it in to the rubber line from the rad. I ran the water pipe from the thermostat housing around between the head and the pass side shock tower, along the back of the engine compartment, than over and down to the return pipe. Thats a lot of clamps. BUT always downward. The water pump and fan run all the time. The other night I made 12 runs at the strip, in 98 degree heat ( 105 heat index ). And this was after the sun went down! car ran @ 228/230 ( degrees, not MPH ) all night, no boil over, no leaks, nothing fell off, nothing broke and drove it home. I have the w/p mounted in the pass side fender well, in front of the tire. It's all in my slide show on youtube.

"chevy V8 fiero-4"

Christine, I am not suggesting another major renovation but when I had overheating problems with my SBC/TH350 combo in my old '53 Chevy pickup, I used the washer type of "thermostat" and replaced the stupid aftermarket cooling fan with a (choke, gasp) Ford Taurus two speed fan with shroud. The original owner bypassed the tranny cooling lines and I made the fan, shroud and washer thermostat in one swell foop when I had to replace the tranny in a field in Waco, Texas and the old truck ran like a new one.

We're at even a higher altitude than you are here in Black Forest and I was sorry to hear your car was running hot. Of course, Mike Gonzalez put a good running 3800SC in my car and even in hot weather and at this altitude (7500 feet) my Fiero runs cool. My cooling fan only runs in traffic. I was surprised at the size of the stock fan and it moves a lot of air but the Ford fan seems better. It may be too large for your application, though. I got it at a Upull/Upay here in the Springs for $15.

quote Originally posted by hugh: Looking at your pictures I could not see a deflector under the radiator.If you don't have that,the car will operate normally at low speed and overheat at highway speeds.The deflector is needed at higher speeds to direct air up to the radiator.

What he said....been there, done that, but didn't buy a t-shirt...

quote Originally posted by Mickey_Moose: What he said....been there, done that, but didn't buy a t-shirt...

Look farther up the thread and you will see a picture of the deflector intact and in good condition.


They are bending the new pipe now I will be picking it up and hope to have it on the car this afternoon. I hope to test out the system this weekend, it is going to be hot so I will know if what we did so far works.

Here is a stupid question, can the fluid flow the wrong way thru the system? Is it possible you have the external pump plumbed in the wrong way, just spitballing here ya know... anyways, really nice looking build ya got there... peace

Pete