I recently got my Iroc up and running again after replacing a cracked block that I purchased a few years ago unknown to me at the time. Anyway I pretty much have the same configeration as before, and the engine is alot cooler now. But after running it for say a 1/2 hour to an hour. Shutting it off, and then restarting it multiple times to dial in the idle etc. I find the engine over heats. I have a Haygen electric cooling fan that works great and turns on at about 160-170º. I also have a 3 core radiator, 160º thermostat, and I'm using a 50/50 mix. I was thinking that I may have a air pocket. I've let the engine run with the radiator cap off til the coolant is about to spill out, but I don't know if thats good enough. Also my engine temp. doesn't get over 180º.

 

does the fan turn on?

the car may run warmer sitting still in a confined space, like a garage, with little air flow.

 

180* isn't overheating...?

 

Yes the fan does come on, and your right 180º is not over heating. BUt when your coolant resevoir boils and over flows out theres a problem some where. And yes I top the coolant resevoir of at the cold water line. If I shut the engine off after running for say 15-20 minutes, the resevoir will began to boil. So I then turn the fan on at the accessory mode, and it cools down. But last night after test driving up and down my driveway (which I can park about 8-9average size cars on. I noticed it was over heating again with the coolant boiling out of the resevoir. The temp got as as high as 180º maybe 185º. So thats why I was wondering if theres a air pocket, or am I just pushing the engine to much in a confined area such as the garage and up and the driveway. I don't want to take it on the street til all the bugs are worked out.

 

As GTA said 180 isn't overheating. Stock thermos are 195 and the fan won't kick on till about 225 (too hot for me). If coolant is coming out of the resevoir, then you must have too much coolant in the system. I have my fan running all the time in the summer cause even driving down the road, it stays cooler with the fan on.

 

I thought so too, but I toped it off at the cold line. Also I didn't top the radiator of from the last time it over heated. So I went up and down the block a couple of times and it started to boil over at the resivoir after I pulled back into the garage to readjust the idle which I had to shut the engine off to do. So I turned to accessary only to get the fan back on, and the boiling stopped.

 

Hmnmm, your radiator might be the problem. You are not overheating, you are not over filling it, and it over flows unless you have the fan on after shut off. Is your coolant res stock? My hunch is it's your radiator. Its not hard to r&r you radiator, I'd try a stock one if you still have it, and see if it happens again.. Engines get warmer when they are shut off, but its normal

 

Its a 3 core radiator though, were as the stock ones are 2 core. I also sold my stock one a year ago.
What if I try water wetter?

 

How much do you loose when it boils over? On my 92 rs the reservoir is larger than on my 86 iroc. How about filling the radiator w/the reservoir empty. If your system is holding more coolant than it used to, than I think you maybe need less

 

new engines always run hot and can boil over. they say not to run new headers on a new engine because they get so hot they crack the coating.
i had a new 85 or 86 cross fire and it overheated a few times during breakin and then no problems for the 3 years i had it.
its part of the breakin.
and is your water pump flowing in the correct direction?

 

Were you directing this question to Americanmouse?

 

If you're positive that you're not overheating, temp wise, its possible you have a bad head gasket or something, leaking compression into your coolant passages.

 

I like that idea, as far as breaking in the headers they are already from my previous engine. If new engines run hotter at first, how long before/miles til it breaks in?

 

about 500 miles. i liked to take mine on a 300-400 mile trip - not all at one time, but lots of driving. i want eveything to seat properly. at 600 miles i change out the oil and filter. we used to use break in oil but not anymore.
lots of sitting and running does make it run very hot.
take it for a long ride, not over 65 but a nice long few hours - but others will disagree. but it cant hurt. carry some extra water with you.

 

Thanks for the info. It is been garage only running and a couple of trips up and down the driveway. I just started to drive it up and down the block this evening. I'm afraid to go to far to soon in case something goes wrong which always seems to be the case for me. (MURFYS LAW)

 

yeah, Murf is always alive and well! I wouldn't be afraid to run w/less coolant. How much do you loose when it boils over? After it boils over, will it do it again if you don't add coolant?

 

If I do this should there be any coolant in the resovoir?

 

I would fill the radiator cold. After you warm it up to 180 or operating temp, shut it off, and see how much goes into the reservoir. That's my suggestion. Just keep an eye on the temp.

 

Great I'll try it tonite!

 

Let me know how it goes.

 

Well, what's the verdict?

 

everytime you shut your car off after it cools enough to let the cap do its job it will release presure into the overflow tank making it look as if its boiling.

 

I was under the impression that he was boiling over the reservoir loosing coolant.

 

My battery died on me from to much cranking I guess, so I have to wait til Friday (payday) before I can try again. I'll keep you posted!

 

I doubt it is overheating. Probably air pockets burping after the engine is shut down, especially if it is new. run it awhile with the radiator cap off to purge air pockets and keep filling with coolant

 

IF YOU ARE LEAKING FROM A HEAD GASKET AND PUMPYING ANTIFREEZE into your engine - just look at the dip stick. if it looks like a frothy milkshake - you got coolant in the oil.

 

I did consider this but the the oil looks good.

This is what I thought, and I should know today when I test it out again.I'm also considering this as well!

 

I was thinking it being a 3 chambered radiator it held more coolant than a stock one, and your reservoir wasn't designed for it. So adding a little less coolant would solve the problem.

 

Wow your having the same problem i am currently. Car runs fine at idle warms up to around 160. Someone must of wired the fan to always be on (so it seems). Driving conditons it warms up to 210-220 which some say is normal but way scary for me. Park and shut off i see it back up in the tank and burpin. i have no oil in the coolant nor coolant in the oil. filled the rad while the car running to get air pocket out, changed hoses and tstat to the 160. Ive bought a tranny cooler to mount after i do the tranny flush. I def dont want my tranny fluid running thru this hot as rad. I know we have been seeing hotter days here in Tx and this is my 1st summer with her but damm almost makes me want to leave her in the garage.

Car burns some oil and needs a head job but i still have a gut feeling im leakin by on the head gasket.

 

agreed thats not overheating

 

Just an update on mine. It seems to have stop, and I let the cooling fan run for about 15 minutes.

 

so you still running around the 180 mark then?

 

Yea it holds at 180º, I need to re connect my fan over ride switch though, because when I shut the ignition off the cooling fan also shuts off. A minor inconvenence, but the temp does get upto about 200-210.

HtOwNs 87Rs
Get a coolant pressure tester you can even rent them at a parts store.
Thats how I found out I had a cracked block a year and a half ago.

 

You stated that your bubbling over problem has stopped? If it did, what did you do differently??

 

I did what was recommended in a earlier post suggestion and that was let the coolant boil out don't re-fill it and see how it goes. Well it worked along with letting the cooling fan run for about 15 minutes.

 

Have you tried shutting off the engine, and not running the fan? The coolant in the block will heat up regardless of the fan running. The coolant in the radiator will start to cool w/o the fan.

 

So your still running around the same temp minus the boiling stuff? Hmmm

 

Yes and no, I have let the engine sit for 1-2 minutes before turning on the fan. Due to working on a couple of other things. But I don't let it sit longer that cause then I get heat soak and it becomes harder to start if at all for about 15-20 minutes. And since I'm still working out the bugs with the tuning I don't like to sit around and wait.

 

Yea!
I think the boiling stuff was air pockets that needed to be worked out.

 

Sounds like your in business dude!

 

well thats good u got ur fixed.....


me on the other hand have a failed head gasket....use the block tester lastnite and it changed the fluid from blue to green within a few pumps.



So list of volunteers lol

 

Wow!
that sucks...