Running too cool!!

JetForeman · Apr 1st, 2003, 07:21 AM

Hi all, my 86 Z24 engine is running way too cool and I can't figure out why. Last fall I flushed the cooling system, replaced the waterpump and fan clutch, and installed a new thermostat. Yesterday I replaced the thermostat again just to make sure it wasn't sticking open and that didn't help.

I'm running out of ideas as to why the hottest I can get it is 164'F verified with a digital temp. gauge.

Any ideas??

Thanks

jadcock · Apr 1st, 2003, 09:13 AM

Only thing I can think of is your heater control valve...is it working properly? It may be stuck open, allowing a lot of unintended bypass through the system. I doubt that's the problem, though, because you'd think it'd run that cool whenever you have the heater on.

Bottom line is, if it's running cool, the thermostat is regulating at a low temperature. It's either stuck open, or possibly not sealing well (allowing coolant bypass). Have you replaced the radiator cap? Maybe a bad cap (low system pressure) is allowing the system to stay cold?

JetForeman · Apr 1st, 2003, 10:20 AM

Jason,

The thermostat is not opening at all, I had the radiator cap off for a while last night while it was running and the fluid was not moving a bit. God forbid I turn the heat on, then the engine really drops in temp. I can't for the life of me figure this one out. Before I did the coolant flush last fall the engine would take a long time to warm up, but it always reached operating temp. and I never had a problem getting heat out of it.

Weird, very weird

aaronford · Apr 1st, 2003, 09:35 PM

Did you install the thermostat properly, if you put them in upside down, they will force open. The poppet should be toward the engine. Also, do you have an air bubble under the thermostat causing it to not read temperature? There should be a vent on your intake manifold? There is on my KA24E. This would actually be causing an overheating condition, but never register hot on the guage or open the thermostat. Just blows the headgasket. Aaron

JetForeman · Apr 1st, 2003, 09:40 PM

good questions aaron, I believe I installed the thermostat correctly, it was off centered with the bleed hole on the top. I would assume the thermostat goes in tail first, or to better describe the spring portion goes into the engine......sound right?

JetForeman · Apr 1st, 2003, 09:43 PM

also if the engine was truly running hot and not indicating it on the temp gauge wouldn't I be able to get hot air in the cabin? If it is cold outside and I turn the heat on it will get cool as temp. gauge drops.

aaronford · Apr 3rd, 2003, 08:00 PM

Not if the water level in the block is below the heater core.

aaronford · Apr 3rd, 2003, 08:03 PM

Yeah, that's right..... hmmm... Did you find the air vent on the intake? Should be on a high point near the thermostat. If this is not it, perhaps you should boil your thermostat with a thermometer to find out when it is opening. Check that versus the advertised.

JetForeman · Apr 3rd, 2003, 08:27 PM

I'll look for the air vent tomorrow but I don't remember seeing it before. I'll let you know. Thanks