Car Overheating randomly....
Originally Posted by strokedls1
It will overheat with the cap off. That is what we are trying to tell you. The caps are supposed to be rated at 18 lbs, but most new caps don't hold that pressure. The coolant system relies on pressure to maintain temperature. I would at least pressure test the system and cap before spending a bunch of money on a pump you may not need. Could just be a 10 dollar cap that needs replacing.
Staging Lane
Joined: Oct 2002
Posts: 82
Likes: 0
From: Tampa
I recently experienced what you are describing. I had the same intermittent overheating then fine for a month.. then overheating for a moment... then fine for a week. I asked all the questions you asked and got all the answers you are reading.
It turned out to be the water pump. It got to the point where it would not hold coolant. It had started leaking from behind the pump.
It turned out to be the water pump. It got to the point where it would not hold coolant. It had started leaking from behind the pump.
Originally Posted by terry s
Cooling system pressure has nothing to do with maintaining the pressure directly. All pressure does is raise the boiling point. So if you were running a motor near or over 212 degrees (at sea level) (with water only) the water would boil and the air bubbles would not carry the heat from the engine. Thus the temp will go up uncontrolably and overheat. Antifreeze and pressure both raise the boiling point of the coolant. This is how modern engines can run so hot without boiling the coolant and overheating.
Originally Posted by strokedls1
I know how it works. I am an engineer and have taken chemistry and thermodynamic classes. The water will boil over if the cap does not hold pressure which flows into the overflow tank and evaporates. The system needs the pressure to raise the boiling point so that it doesn't boil and over heat the motor.
However you said "The coolant system relies on pressure to maintain temperature." If you have time you might read my post again. I stated that the pressure does not directly maintain temperature, which it does not. It does indirectly help maintain temperature by increasing the boiling point along with the antifreeze's ability to raise the boiling point. And you are absolutly right that the system needs pressure to raise the boiling point (if I am not mistaken I think that is what I said). 
My car gets to 225 or so but only in 100 degree Texas weather and standing in traffic. Vettes always run a little warm in Texas heat from what Ive seen.... Stock fan setting is way the hell up there I changed mine and have both coming on around 190....like I said it still gets on the warm side in this houston heat. My oil temp was at 240 today!!!!
Originally Posted by HolyShiznit
Ok I have NO idea how to really explain this. I bought a new water pump today and as I was going to install it I decided to try to let it air itself out one more time just to see what would happen. Car started up.....I let it sit for a full 17 minutes. It never got above 174 degrees!!! I drove it around the block and no over heating, then I took it farther, and it was fine!
I left the car in the garage with the radiator cap off, I honestly have NO idea what exactly happened but the car is fine. I drove it around all afternoon and night. I modulated the throttle, went from freeway to inside the city and all sorts of stuff. Everything seems fine for now!
I left the car in the garage with the radiator cap off, I honestly have NO idea what exactly happened but the car is fine. I drove it around all afternoon and night. I modulated the throttle, went from freeway to inside the city and all sorts of stuff. Everything seems fine for now!
