im new here, and i really like the ideas and advice ive seen so i joined up! i have an 86 trans am ive been workin on for awhile...its got a 350 4 barrel dropped in i do not have a thermostat in it. i know that shouldnt be, but i wanted to know if anyone else has had a problem with overheating at idle...when im sitting with it and not moving anywhere the temp jumps rapidly is that common? im running 2 electric fans, ive flushed the coolant an added fresh antifreeze, the heads seem fine to me there is no indication of em being blown....driving it keeps it no where above 170 but sitting for long time periods heat it quick! is there any way to make this breath any better? thank you! its a pleasure to be part of this club!

 

Factory fans or aftermarket? Digital thermostat or mechanical(for the fans)?

 

Welcome to TGO mate. It needs a thermostat. Or else no coolant will circulate. The thermostat communicates directly with the Coolant pump. No thermostat, no coolent pump, no coolant. Luckily the thermostat is really easy to instal/swap out in chevy small blocks. And a good 180* stat is only like $5. Then its like $1.50 for the gasket, and andother $3-5 for the liquid gasket/sealant. Def. want to get the liquid gasket/sealant. Unless you want coolant spraying all over your engine block. and that is no bueno.

 

well the fans came with the car, but they sure as hell cant be stock fans i got them rigged up to a switch so i flip it and start the car. and i always thought the thermostat just restricted coolant flow untill the motor was hot enough for it to allow it to flow thru the block?

 

Yes, but it also senses the the temp of the engine and comunicates with the water pump. To the best of my knowage. And even coolent flowing through the engine, without the thermostat to regulate it, you might be pumping hot coolant though the engine block. And that would make it over heat. Either way you need a thermostat or it'll over heat.

 

Sorry but that is completely wrong. The thermostat simply restricts coolant flow until the engine reaches operating temp then opens to cool the engine. Not having a thermostat will keep the car running too cool not too hot.

 

So you keep the fans on all the time? When I asked about the thermostat I was referring to the fan thermostat if it has one.

 

thats how my electric fan is..it was like that when i bought it. theres a blue wire running from the fan motor to a switch under the dash which does no good cause the fan stays on in any key position but off. whether switch is hit either way. but just my $.02 on that part.

 

Weird. I thought it worked that way. The way you said it worked I mean. Guess that automotive class I'm taking to re educate me is completly wrong. How great is that? I actually payed to unlearn something. And even so, if the coolent was constantly flowing, wouldn't hot coolant be coming back into the engine block? The coolent needs time to go through the radiator to cool off right?

 

i agree. no thermostat will usually make an engine run hotter in a warm climate, cause it doesnt get a chance to cool in the rad.

 

have you checked to make sure the fans are turning the right way. as in turn the fans on and see which way its blowing air. also check in fron of the rad and ac condensor for blockage...ie leaves and junk. the tstat blocks collant from flowing into the rad until the car reacches op temp. not having a tstat will make it take a lot longer to reach op temp and causes engine parts to wear faster. put a 180* tstat in there. also does it overheat on the highway or just when idleing?

 

That's not what you said in your earlier post. When the thermostat opens it allows more coolant to flow through the radiator cooling the engine. Simple. If it is always open It will run cooler because coolant will constantly be flowing through the radiator. All there is to it end of subject.

 

Yeah check the airflow of your fans they may be wired backwards or the blades may have been installed backwards. It definitely sounds like the fans being that it stays cool during driving.

 

I mean I thought that was how it worked, then I took this class and it said different, then I came here, and now i know the class was wrong. And I've seen coolant boil if it's not cooled properly. And boiling coolant tends not to absourb much more heat. Unless you have some sort of scientific proof that coolent, factoring in unrestricted flow due to lack of a thermostat, is cooled off in the radiator quickly enough to still absourb heat effectivly when it is pumped into a hot engine, I am unconvinced. Show some proof so that I might be educated.

 

These engines are made to run with T stats, please put in a damn t stat.

And the T stat stays CLOSED until the engine reaches X temp. When it reaches X temp, the T stat opens, allowing COOLED coolant to flow into the engine and cool it, while the HOT coolant is pushed into the rad. The t stat will then close, until X temp is reached again, allowing for a more constant engine temp(good thing) and giving the coolant in the rad time to cool.

Your both misinformed. if there is NO t stat, the engine might run cooler under certain conditions(and will take longer to warm up), however, if it doesnt have time to cool in the radiator, and is quickly being passed through, where does the cooling happen? It just pushes hot coolant back through the engine at a constant rate.

doesnt matter how fast you move the coolant, that doesnt cool it.

All on the same page? cool.

 

86TransAm:

The t-stat is there to let the engine warm to operating temp, and regulate that temp once there. I assume you have removed it in an attempt to fix your overheating problem. Won't help, will just result in wild fluctuations in temp, which in turn makes troubleshooting much more difficult. Put one back in.

This tells me that while you're moving it runs cool below 170, but overheats stopped at idle. This would indicate that the added airflow from the air dam when moving, is enough to bring the temps down. Relying on the fans alone when stopped, your temps are going up. Suggests the fans aren't up to snuff.

Questions:

Are the fans actually running? Or perhaps they are running backwards as mentioned above?

Are they shrouded so that they draw airflow across the whole area of the rad?

Is the rad cap holding pressure?

Is the water pump on the way out?

Is the rad full of crap?

Is it really overheating, or is the gauge reading just alarming you?

Edit: Oh yeah don't forget timing, might have too little at idle, raises the temps.