BOZS89IROC

I just rebuilt my engine, installed it and it runs great. The only problem is that it overheats. I checked the water pump and it pumps (brand new pump.) I also pulled the brand new thermostat and ran the water neck wide open it still overheats. The fan kicks on at the right temp and there are no coolant leaks. There is a 50/50 mixture of coolant in the brand new radiator. The radiator is the correct one for my car, it is aluminum.
There is a coil in front of my radiator that I believe is for the A/C but that is the only thing that I can think of that would be affecting my temp. I dont know if that would block enough of the air flow to overheat the engine, but it's the stock coil and I believe it's in the correct way.

Any info is greatly appreciated.

BOZ

AndrewC

is the water/antifreeze boiling over or your just going by the gauge?

TheGreatJ

Check your airdam...make sure it's there and in one piece.

ebmiller88

Definitely check the air dam or just get a new one from Dal or your dealer, they're cheap and apparently a bit larger than they used to be. Also, try blowing compressed air from the fan side of your radiator out the front. Sometimes leaves, debris, cats, and other crap will clog it up.

HTH...Ed

BOZS89IROC

The engine over heats while it's just sitting there at idle. It's a brand new radiator and the air dam is in place and intact. The coolant is boiling over and the guage reads about 240-250 deg.
I'm wondering if it could be the timing. I timed it and set it at 6 deg. BTDC like the sticker says. But with new rings and bearings would this be enough friction to cause a big increase in temp? I also honed the cylinders. It has trouble idling also which leads me to believe I could be running too lean and need to adjust my mixture on my E4ME.

Thanks again for your input and any that may come along.

BOZ

AndrewC

Sounds like its getting complecated. try running the engine with the rad cap off. This will tell you if the coolant is circulating properly. let the engine warm up a bit, about to 140-160 degrees. then go to engine compartment and open throttle, the fluid level will drop in the rad, when rev-ing the engine, and you should see new fluid replacing it from the top hose. when you throttle down it might over flow a bit and spill over on the ground. let the engine cool a bit before replacing the rad cap.

if your thermostat isnt in this wont work correctly, it should open at what ever temp rating it is. otherwise it will cycle constantly.

if the thermostat is not working the rad will not cool down the fluid before it returns to the motor. it will eventually get too hot.

you can boil your thermostat on the stove, in water, and you'll see it open, if it works fine. if not replace it

is your new rad 3 or 4 core? you might need a 4 core.

Rice Killer87

what size injectors r u running? do u know what fuel pressure u have? running lean might make it run hot but im not sure about actually overheating

TheGreatJ

Running lean will heat it up. A new engine with tight rings and very close clearances will run hot for the first couple hours also. The combination of the two MAY be enough to boil the coolant over.

Also, does your lower radiator hose have an anti-collapse spring in it? A new water pump may put enough suction on the hose to actually suck it shut and cut off the coolant flow.

87IROC-Zowner

Two things come to mind other than what's been mentioned.

First of all, are you sure you have the correct water-pump on your engine? Single belt (serpentine) engines need reversed water-pumps. The older standard V-Belt with a micro-v on the alternator needs a regular water-pump. I was given the wrong pump for a '89 IROC (which needs reversed pump).

Second, with the thermostat out of the system, your asking for problems. The coolant flows too quickly through the radiator and doesn't have time to cool down before it is recirculated in the engine. The thermostat has more than one job. It causes your engine coolant to heat up faster and it restricts the flow so the coolant stays in the radiator longer.

As mentioned in other posts, make sure your lower radiator hose is not being collapsed and that your air dam that is under your car is intact. This won't cause idle/ 0 mph problems but it can cause your engine to over heat while driving down the road. Something else to check is leaves and debris build-up between your radiator and your A/C Condensor.

90rocz

If the thermostat is stuck open it will take a long time to reach operating temp, then overheat ,as said, b/c it passes thru the radiator too quickly.
Is the radiator cap holding pressure? If not it will boil at a lower temperature. Check the top hose at normal operating temp, it should be too hard to squeeze.
Running lean will definitely raise the temp too, read the spark plugs.
I have bought 2 bad, brand new, thermostats this year. Opened too slowly and not open enough, I exchanged them and fixed it.
Even with the fans coming on around 220*going off at 195*, it still hits 240-250*?

1985_305

I dunno if this was mentioned above but did u check to see if your oil pressure?