got my car back, driving from atlanta to statesboro, i get to the metter exit, (approx 150 miles from beginning of trip) and the temp gauge goes off the chart again, does it on long trips now consistantly


get to the gas station at the exit, notice there is a bunch of water that has come out of the overflow resevoir. it is also full.

open the bleed screws, just air.

finally get the cap off carfully, let the pressure and some hot water get out of the way, get the cap the rest of the way off, and notice that the radiator is empty AGAIN.

put 2.5 gallons of water into it and it runs right back where it should again.


so...i called my mechanic and he said the radiator cap could have gone bad, cuz on his impala (LT1) his cap went bad, and it was doing the same thing...otherwise it would have to be a head gasket.


my question is, could a bad radiator cap be causing the coolant system to be come overpressurized and blowing coolant out through the overflow resevoir. the resevoir is full of water as i said, so it makes sense that it's blowing it out through the overflow, just not sure. i'm really not hoping it's a head gasket.

 

...not that it is overpressurized, but that the cap is not holding the pressure and letting it escape into the reservoir. It is a possibility.

 

makes sense, got a new cap, gonna try it out tonight and see what happens.

 

Running just water will contribute to overheating, too. Use 50/50 coolant.

 

i never really understood that.

the way i have always seen it is that coolant only keeps it from freezing.

someone correct me if i'm wrong




and thanks again shoebox, the problem seems to have gone away with the rad. cap. if i ever see you in person i def. owe you a good bar tab for saving the day.

 

Water is acutally a better heat conductor, but coolant can lower the boiling point a little.

 

today it blew all the coolant out again and overheated.

there is water everywhere near the overflow vent cap.

got a new rad. cap on there, new thermostat. no visible leaks.


am i looking at a head gasket now? i'm gonna drain the oil and do a change tonight, to look at it. but i dont think any is in the oil because it's all blowing out of the overflow.


btw, it's been about 10 degrees hotter than hell down here in statesboro lately, could htat be causing it? (98-103 with 110-135 heat index)

 

I'm interested in how yours turns out.

My radiator side tank cracked on monday, I replaced it Tuesday, and now whenever I stop driving and turn the car off the coolant boils out of the overflow tank. I thought it was the cap, but I replaced the cap and it's still doing it.

However, mine is not overheating at all.

 

Figured mine out. My radiator has 2 lines connecting directly under the radiator cap. The top one SHOULD be the line from the overflow, and the bottom one should be the line to the water pump. I had mine switched, and that caused the problem.

 

my lines are hooked up correctly. i'm gonna try to get a leakdown test done on it today or soon.

 

The radiator cap is important to maintain pressure within the system. As pressure increases, the boiling point also increases.

You may or maynot get results from the leakdown test. If you don't get conclusive evidence from it, pressurize the coolant system. Then if it drops, start pulling plugs.

 

Try to find a "block test kit." It will have a solution that you put in a bulb that sucks some fumes out of the radiator. If combustion gasses are present, it will change colors. I haven't seen one of these kits in a while, but then again I haven't been looking for one either, so you may be able to find one. If you come up with positive test results, you've got a bad head gasket or a crack somewhere in the head or block...

 

i've never heard of a block test kit. that is one awesome idea though. if i can find one i might look into it


it's becomming an intermittant (sp) thing. i did a thorough bleed of the system a day or two ago, and it's warmed up a bit in traffic, but nothing over 190.

i am beginning to think it's a clog somewhere in the radiator.

so far it hasn't overheated in two days. so here's hoping it was just a terrible job of bleeding the air out

 

just my thought...you said in the start of your thread that it overheats on long trips. humm, this sounds crazy but i had a z overheat on long trips due to the bottom spoiler had gotton broken off....did fine on the fans at normal speed but not at highway speed

 

air dam is fine, got under there and inspected it recently. thanks for the input and it's def. possible. but like i said, i already looked at it.