I have an 87 Z28. I know this car is supposed to run hot normally.. When driving even on a cold day, the temp goes up to 240 or even just to the red line at times and then the fans come on. The fans dont normally come on until a little over 240 or even right before the red zone. I recently just had the heater core replaced, the thermostat replaced from a 195 to a 180, and the radiator repaired for a little damage but not too much. Im thinking it could be from the radiator repair but it was very moderate damage from the fans running. If anyone could help in anyway possible it would be greatly appreciated...Thanx

 

The fans come on at 220, not 240. The ONLY thing that sould cause that to change is if somebody reprogrammed the PROM in the computer, which isn't likely. I'd guess that your temp gauge is not terribly accurate. You should have a scan tool hooked up to the car so you can see precisely what the temp is when the fans come on. I suppose it's possible that the coolant temperature sensor that the computer uses has failed, and it may be worth changing for what it costs. Usually that just works or it doesn't. I've never seen one start giving numbers that were off by 20 or 30 degrees. Just be mindful that your car has 2 of them. The one that the ECM uses is in the front of the intake manifold (at least on TPI cars). The one that your gauges uses is in the driver side cylinder head.

So anyway... the most common overheating issue with thirdgens is a missing or broken air dam. There's an air dam right below the radiator that sticks down under the car to force air into the radiator. since these cars don't have much of a grill, this is a necessity. Make sure yours is there and in good shape.

If none of this works, it's possible that you might have air in the system somewhere. I've never had this happen to me so I'm not too sure how to get rid of it. It's also possible that the lower radiator hose is collapsed. It's possible that there's a blockage somewhere.

 

Thanx for your insight this will be very helpful to me. I am going to take a look at it this weekend. Hope fully ill find a solution. Thanx again!!

 

If your fans are not coming on at all then it would probably be the CTS that is faulty.

I am with Jim on this one. Mine was running hot and then I finally got around to hooking up a scan tool to it and my guage is about 10* or more off. But now with the new waterpump, CTS, t-stat, flush and filled radiator, and the chip being reprogramed I am running nothing over 160* which is really nice.

 

a scan tool is a must. i hooked up one on mine and come to find out it was nearly 22* off. i also found my converter and muffler were just about completly stopped up.now it runs 160 all the time

 

My rad was giveing me trouble by boiling over. It turned out to be the rad cap had lost some of its spring strength.

Rad caps are cheap, too

 

Hey guys thanx alot for all the great info. im gonna get to the bottom of this thing. Thanx again.....

 

Feel your radiator where the hot water comes in and it should be hot. If there are sections of your raidator that are cold, you might have a problem with the radiator. It should get gradually cooler as you head towards the exit.

 

Once you've inspected all the obvious (stuff above) and confirmed everything is in working order, the next phase would be to modify your fan turn-on point(s). My article:

http://www.thirdgen.org/newdesign/tech/cool.shtml

BTW, is yellow the original color of your '87 Z? If so, I'd love to see pics as yellow '87 Z28's (not IROC-Z's) are somewhat rare. FYI, this is one color you could not get an '87 Z28 convertible in!!

 

Yellow is the original color of my car , but i recently had it painted corvette competition yellow instead...i have pics tho..

 

What they said above, & I've also found that whoever designed our cars, let them so that debris will collect between the air conditioner & radiator & screw up the air flow.

Remove the plastic cover from the top of the condenser/radiator, & shine a light down in. Most debris seems to be down towards the bottom!

I have had better luck using an air hose rather than water with getting most of it out.