So. Here's my "Story" 85 GT (2.8 auto)

I've had the car for a few months, and about a 2 weeks ago I was driving down the highway when my coolant light came on, and I looked and the temp gauge was way above the red. Immediately pull over and let the car cool off. Started driving again, and within a few minutes it was over heating again. Let it cool off and pulled the thermostat, I had decided that i was going to replace it.

Replaced the t-stat with one that I know was working before, bled the coolant system, all was well and good. I was driving over to a friends house on monday, and it over heated again. so again, I pulled the t-stat.

I talked to the previous owner and he said that it happened to him a couple times too, and he also said that he replaced the t-stat the last time it happened.

Does anyone have any idea why i would keep on having this problem? I'm thinking possibly a bad head gasket that is allowing air/gases to enter the coolant system from the cylinders, but I'm open to any ideas that people have. One thing that i did think odd is when i have the t-stat housing cap off, and you start the car, the coolant starts flowing, and then just BLOWS out of the hole (with the car at idle).

Sorry for the long ramble, but I try to be thorough in my explaniations

Does your radiator fan kick on at all? Easiest way to see if it's working is to turn your AC on. It should kick the fan on as well.

Edit to add:

Plus the Fiero cooling system is a biatch to bleed properly. It took me I don't even remember how long to finally get it back in normal temp range after my heater core blew out. That could also be another thing to check? See if it's leaking at the heater core(And check those hoses for dryrotting).

[This message has been edited by N3M3S1S (edited 09-17-2009).]

Yeah, the rad fan functions as it should. A/C kicks it on, and so does the temp switch in the back. I've throughly checked the entire system for leaks. There aren't any, and all of the hoses are in good shape. That's the part that's really baffling me..

Do you have steam from the exhaust?

I agree, check your heater core. I had a leaky one for a while & never noticed it. Lost quite a bit of coolant.

I am having a similar problem. Only because I replaced the sending unit. It seams that every time you open it up you have to bleed it a couple of times before it is OK. So tomorrow I will bleed it 2 or 3 times and again on Saturday. Last time I did this I jacked up the back of the car. That seamed to help. Good luck.

yeah, it looks like it could be steam coming from the exhaust, it doesn't smell horrible though, just like normal exhaust. and i haven't ever lost any coolant...the level in the bottle never changes...

A small amount of steam when you first start it is normal.
A large cloud is not. A large cloud is a blown head gasket. Any coolant in the oil? Take off oil fill cap and see if it is milky in there.
Are the radiator hoses getting hot? If not did you crush a coolant tube? Is a hose crimped?

quote Originally posted by stinky817: yeah, it looks like it could be steam coming from the exhaust, it doesn't smell horrible though, just like normal exhaust. and i haven't ever lost any coolant...the level in the bottle never changes...

Dont trust the bottle! I found that out the hard way. The bottle is an over flow.... I was 2 gallons low on coolant but the bottle level was where it was supposed to be.

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86 GT
87 coupe restoration project.

quote Originally posted by stinky817: I'm thinking possibly a bad head gasket that is allowing air/gases to enter the coolant system from the cylinders, but I'm open to any ideas that people have. One thing that i did think odd is when i have the t-stat housing cap off, and you start the car, the coolant starts flowing, and then just BLOWS out of the hole (with the car at idle).

Try this: With the engine cold, start the car and run for only a few seconds. Then shut it off and open the t-stat cap. If there is any pressure at all, or any foaming, then you may indeed have a bad head gasket.

[This message has been edited by TopNotch (edited 09-17-2009).]

good thinking there top notch. i'll actually go try that now.

steam comes all the time... and nice cloud of i don't even know what color smoke when i start it... it varies...can be blue, can be white, depends on how long the car has been sitting... but it almost always smokes on a start up. even after sitting for 30 minutes.

it's not milky under the oil cap... if i knew there was coolant in my engine, the car would be parked :P yay for tasting oil haha

My radiator fan only comes on when the ac is on. does this mean I have a bad temp sensor?As long as I keep the one of the AC modes on the car stays cool. But if I turn it off the car will overheat.

quote Originally posted by kwaidonjin: My radiator fan only comes on when the ac is on. does this mean I have a bad temp sensor?As long as I keep the one of the AC modes on the car stays cool. But if I turn it off the car will overheat.

Sounds pretty possible. Will it go in the "red" overheat? Or will it just go up a bit? A factory Fiero runs 220 to 230 degrees. I believe the fan kicks in at 220? Someone feel free to make me look stupid. I'm not EXACTLY certain about this one.

I don't know my temp gauge is pegged all the way to left.So the gauge is broke.

ok, so, i checked the pressure thing by letting it run for about 15 seconds, removed the cap, and no "pssh" or foamy coolant. i decided to drill a hole in my thermostat and put it back in. temperature was acting normal today after i did so. i also decided to do a compression test on each cylinder. i got about 150 from each of them (varied between 145-155) so that wouldn't make any sense for a blown head gasket. we'll see how the temperature goes in a few weeks. hopefully the "holey" thermostat works

kwaidonjin: that's what your problem sounds like. the fan switch, it's a switch that is in the intake manifold near the thermostat housing. it's a green w/ white wire. you can try disconnecting it and grounding it out to make sure the wiring is good. if you ground it with the key on, the fan should kick on when you do. i'd suggest getting a new temperature gauge. i have found that a broken one tends to hide problems

O.K. thanks I will check that out.

Well. It happened again today... Was driving home, and BAM. over heated again. So the thermostat is back out and.... I'm still baffled

quote Originally posted by stinky817: Well. It happened again today... Was driving home, and BAM. over heated again. So the thermostat is back out and.... I'm still baffled

Stinky817,

Have you used a multi-meter to test the temp gauge/temp light sending unit which is located next to cylinder 5? If not, I suggest you do to get a true reading of the running temp. Fiero temp gauges are know for giving false readings. I write this because I spent three weekends chasing a cooling issue that never existed.

https://www.fiero.nl/forum/Forum2/HTML/099336.html

Follow the link above to find the table that you use to compare to the readings from the multi-meter. This will determine if the engine is really overheating or the gauge is misleading you.

I hope this helps.

Abe

[This message has been edited by aconesa (edited 09-19-2009).]

does it overheat where the coolant is bubbling out?

aconesa: i'm pretty sure that it's accurate...every time it happens i end up losing coolant through the overflow bottle.. it just pours out of the cap on it


and i was thinking about it today...the only times that it's happened is when i decided to "push" the car harder then i normally do, each time it was under hard acceleration while passing someone (makes me look like the ass, go to pass someone, and then pull over on the side of the road *rolls eyes*) so i'm wondering what that could mean. oh, and it's not long term hard accel. just maybe 10 seconds tops.

So it happened again today... Without a thermostat.... I'm thinking possibly clogged radiator, or... I'm just not too sure. All of the hoses had pressure on them when the car was over heated.... I'm currently sitting on the side of the road to let it cool off and see how much it takes to fill the system back up. And it happened again while I was "pushing" my car... Still at a loss with it

I would bet a paycheck that it is still air in the cooling system. When my radiator blew out last summer, I replaced it and burped the system. This has to be done with the rear of the car in the air, you can't get around that. The coolant fill has to be the highest part of the system. I thought I could get away with not burping the heater core, I was DEAD WRONG. Just enough air gets trapped at the heater core to make it overheat. Follow Ogre's burping directions to the T, and I would be willing to be problem solved. But you gotta stop overheating that motor, or it will soon be head gasket time. Good luck.

Andy

I just did a flush on my radiator, flushed it 3 times and still had black rusty gook coming out. I hope i don't have the overheating problems because of this. I burped the sytem to best of my ability.did not jack up rear of car though.

Lot of good ideas above but I would pick some low hanging fruit first, replace the radiator cap and the thermostat cap, $12 total, and reburp the system. Then start looking for leaks along the coolant lines. Then move on to the high dollar possiblities.

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RickN
White 88GT 5spd
White 85GT Auto
White 99 F250SD 7.3PSD 6spd
1956 Ford 860 Tractor w/ Freeman Loader
20Ft Tilt Bed Trailer

[This message has been edited by RickN (edited 09-28-2009).]