hi, i am looking for some help with my 1986 IROC-Z. it has a bit of an over heating problem and im not sure what to do. the car has no heater core in it or a thermostat but i figure why have a thermostat if there is no heater core. if i can i want to avoid putting in a heater core. does anyone have a solution to this issue? please let me know.

what type of water pump? how big of a radiator, whats ur ignitiion timing set at, what else did you do to the engine

How hot is the car getting? I would put the thermostat back in if I were you. Also, try hooking up a manual fan switch, that could help you out alittle.

im not too sure of the water pump or the ignition timing. like i said i just got the car not too long ago and i havent really taken it apart yet. i was thinking of hooking it up with the manual switch fan but isnt there no reason for a thermostat if there is no heater core? i belive the fan in the car is a little over sized also. thanks.

You dont have to have a heater core if you have a thermostat or not. I put a thermostat in my car because it was running too cold this winter. Does the car over heat while driving or just stopped?

The reason for a thermostat is to allow the engine to reach operating temperature quickly, then keep it there (providing the cooling system is adequate). A cold engine may wear faster because the clearances change as the temperature changes. It also helps to regulate the flow rate through the radiator. Believe it or not, the coolant can flow through the radiator too quickly and it won't have enough time to transfer the heat from the coolant to the radiator fins. Even drag cars which don't run thermostats usually have a "restrictor" (like a big washer) in the thermostat's place to regulate the flow rate. The "heat" available for heating the interior is secondary. You do not have to run a heater to need a thermostat.

That being said, there are a lot of variables which affect an engines operating temperature. Many of them have already been stated. Please provide as much information as you can to help us help you.

What would be considerated to be to cold for our 3rd gens. I believe I am running in the 180 range. Would that be considerated to be to cold. From the factory they have these cars running warmer, around 220-230 which I consider to be a little to warm. Any input would be great

I've got my car running between 175-180 right now and its fine. I would imagine that anything below 160 would be too low, just my guess though.

This is a question I've been attempting to have answered for myself. Not necessarily how cool is too cool but what is the optimum operating temperature. From what I've gathered 200'F is best for wear and power. Now this doesn't take into account that our third gen's stock tune makes more power at lower temperatures. This is because of fuel and timing settings are more aggressive at lower temps. But I digress, the question is how cold is too cold. Personally I believe that 160' is too cold but a lot of folks run there with no apparent problems. Cooler operating temps don't allow the oil to get hot enough to burn off the contaminates that a gas engine produces. You get more sludge build up and wear. Of course too hot (say 200+) isn't good either. High temps simply bake all the gaskets, seals, hoses and other stuff under the hood. I run mine with a 180' t-stat and have my fans come on at 195' and off at 180'. In cooler weather (50's-60's) it runs around 175-180'. I like to see the temp run 180-190' range.

i belive that the car runs at 220-240 from what the guage says but i cant be confident in the guage. the car has hit 260 and i pulled over that was on my way back on the highway from long island. when i pulled it over the car puked a little and i waited for it to finish cooling and i had to stop several times for this. i think the car mostly gets hot when it is sitting. i belive the car has got while running on the road as well. so are you saying that the flow may be at too high of a rate? because if it is ill put a t-stat back in the car... thanks.

you could possibly have bad head gaskets too

In regard to the gauge, when I'm datalogging throught the ALDL the running temp is much lower than the reported temp at the gauge. The second hash mark between 100' and 220' is actually about 175-180', the 220' mark is actually 195-200'. That's on mine and you may want to get a scan tool or hook up a temporary gauge to see if yours is off.

As far as installing a t-stat it certianly won't hurt. I recommend having one.

Why would ignition timing change/effect coolant temperatures?

First thing I'd do is put a 180° stat in the original poster's car. Single fan? Dual fan? Are they coming on?

definatly make sure ur fan or fans is coming on, i had a problem with my 92 overheating and the fan wasnt coming on, now i got a manual switch and it worked wonders, and only took me half hour or so to do. its pretty too

Put a 180 t-stat, and make sure ur fans are working. also, i think if his head gaskets were shot there would be more symptoms than overheating.

whether you believe it or not ignition timing can have alot to do with how hot or cold an engine can run too much timing will cause an engine to run hotter. too little it wil not run properly and will run cooler. i have an article somewhere on it ill have to dig it out.


and as far as headgaskets go an engine can overheat if cumbustion pressures are leaking into the cooling system and you probably wont see any signs of white smoke since the coolant is not leaking into the combustion chamber yet. i have seen quite a few like that. how many miles on this engine?

Make sure your air deflector is intact. It will heat up fast without it, especially at standstill, or stop & go.

also check to make sure your electric fan is working i know mine if i idle for a long period of time my fan wont kick on since the temp prope for the the fans doesnt work right thus why i just bought a new fan switch and need the plug for it. while driving its awesome car doesnt even see 190* but just a thin to check

ok to start, the car's fan is hooked up and in tact as well as the air dam. the fan is hooked up into the ignition so when the key is turned over the fan automatically comes on. im not sure on the head gasket situation, but ill check. if the car's fan runs off the ignition should it have a thermostat? also what if i was to run the piping back through the fire wall for more travel would it cool it down better? and just to remind you, the car has no heater core in it. someone also suggested to me that bigger headers might help as well.
-thanks

Well first like others have stated before install a 180 or 195 degree t-stat so the coolant flows at the appropriate velocity. Also your post states that there is a 383 in the car. How heavily worked is the motor? What kind of cooling fan do you have in the car? If an automatic does it have an auxilery cooler for the transmission? The factory fans are pretty lame in these cars to if you have a stock non shrouded fan I would start by pressure checking the system and if that comes out alright upgrade to an aftermarket shroud and fan

the cars fan i belive is stock. it is an automatic but i think i am swapping it for a t56 soon. the car has comp cams in it and aftermarket lifters. from what i can gather the car has higher compression ( around 10:1 ). i am still wondering if i should run the hose back through the firewall so that the coolant has more flow so that it can cool down faster. and i will put in the 180 t-stat for better velocity.
-thanks

I run my car in the summer in 95 degree days and have no problem with cooling issues. I still have the stock radiator, but have a cooler fan switch and an electric water pump with 160 stat, and aux trans cooler. Works perfect!

I have a worked 355 in my 88 and it would overheat in traffic when i had the stock dual heavy duty fans. I installed a summit shroud and 16" fan with a manual switch. On a 100+ summer day with the fan going in bumper to bumper city traffic the car doesn't go above 190. I also have a flow cooler water pump in my car they have a neat rotor design that increases flow at lower RPMs but not at upper RPMs when a stock pump moves enough coolant. With the motor being built the way it is i would strongly recomend the fan upgrade it cost 170 bucks and it is one of the best upgrades i have done to my vehicle