I have an 81 and am in need of a 15 lb. radiator cap. I can not find one anywhere. In fact, when I go to the auto parts stores they put in the computer: year, make, model, etc. and they come up with 16 lb cap. So I purchased it, now my car is running hotter (20+/- degrees hotter). I checked the owner's manual and it says 15 lb cap. The cap I am replacing is a 15 lb cap. Is it too much to ask that I would like a 15 lb cap? not a 16 lb!! Would a 1 lb difference cause it to run hotter? If not, perhaps I have another problem. Any suggestions?

Thanks,
Stormy1

The 15lb cap was still available from GM. It is now plastic instead of stainless as original. A 16 lb cap should actually help it run cooler than a 15 lb all things being equal. The higher pressure water is contained at, the higher it's boiling temperature.

Ok. Why would it be running hotter then? It hasn't run this hot ever. Not even in heavy traffic in 100 degree heat. What might be causing it? Any suggestions would be appreciated. BTW. It has only 40000 original miles on it. (Factory air in the spare)
Thanks,
Stormy

Stormy1,
I have to agree with markdtn. For every lb. of increase in the radiator cap, it raises the boiling point a couple degrees in the system. Don't run more than 16 lbs on your system. Too much pressure will give problems down the road.
Why is it running 20 deg. hotter, I dunno. Could be a "fluke" of some sort. But you gotta start looking at other things in the cooling sys. How is the fan clutch? How old is the thermostat? When was the last time the system was flushed out? Is there a lot of debris between the A/C condenser and radiator. Maybe the gauge or temp. sending unit may be off or faultering. What is the temp gauge reading?
Sarge

Sarge,
It is running about 210, which is hotter than it has ever run. (200 was max) The check engine light comes on at about 180+,then the thermostat opens and it cools a little to about 160+ then goes back up to 200 after driving a little more and up to 210 if I accelerate aggressively (put my foot in it). Check engine light stays on, occassionaly going out, then coming back on. The system probably needs to be flushed out as well. I have put about 2000 miles on it since I bought it in March and it was only driven 100-200 miles every year for 6 years by previous owner. I do know that the lower radiator hose was replaced before I bought the car and it appears that it was cut too short Maybe I should take it in and have someone give it a complete physical? Before something happens and I am on the side of the road striking the "damsel in distress" pose?
QUESTION: Will it harm the engine running that hot? If not, no worries?
Thanks,
Stormy

You want to be sure that the temperature is accurate. The gauge is notoriously inaccurate-see other posts. I would take a good hard look at the whole system. Is the front air dam in place? Are there a lot of weeds/debris between the radiator and A/C condensor? Are all the rubber seals in place between the radiator and core support and core support and hood? Is the fan shroud in good shape? How is the fan clutch? How is the water pump? I have never seen a Chevy pump lose an impeller, but I saw a slant-6 chrysler pump lose an impeller internally and it did strange things with the temperature-never leaked a drop of water. I would be concerned with the SES light going on and off, I would want to know why. My personal opinion 210 is OK, 240 is too hot. Good luck with it.-Oh one more thing-make sure there is a spring in the lower hose. They can collapse under suction without the spring in there.

|UPDATED|8/15/2003 12:23:25 PM|/UPDATED|

No debris anywhere, this car is super clean. But the spring in the lower hose I can't be sure about. I think the best bet would be to take it in to the local Corvette Care shop here and have them check everything out. This car was always garaged, but I know that after time, things (seals, gaskets, hoses, belts, tires) rot, deteriorate and need to be replaced. Thanks for your input.....save the wave.

Stormy

Well upon leaving for work today, I noticed a puddle of coolant under my car. Under the heater core. Carpeting on passenger side of interior was only a little damp, so I am going to bypass the core for now until I can have it replaced. Thanks for all your help. Really appreciate a site where I can go with a car problem and get a response. Take care and save the wave.......

Stormy

I am still going to have it completely checked out, though.

If you have a coolant leak you will not have the 15-16lbs in the system and that could definately cause overheating. Let us know what you find out-probabaly bad heater core or hoses.

Hi Mark,
Yes, it was the heater core, I have bypassed it for now. And the upper radiator hose, the hoseclamp wasn't tightened enough by previous owner. He had replaced the hoses before I bought it. This morning on the way to work, it never got over 195. Thanks for all your help. Really appreciate this website and all the advice.
Save the wave.....

Stormy


|UPDATED|8/18/2003 9:10:33 AM|/UPDATED|