Overheat/boil over problem

[MikeyMike]

Ok so at the nanuet meet last week, well even before that when we met up at a pre location. My temp gauge shot all the way up as we left the parking lot.. Once on the highway it leveled off to normal and didn't overheat again afterwards. Once arriving at nanuet mall I allowed the car to cool then "burped" the radiator maybe think it was air in the system.. After that we drove to the palisades mall (maybe 5-6 miles) car didn't overheat but when idling in the parking lot for 5 minutes the reservoir tank started to boil over n coolant was overflowing through the tanks cap.

Again I let it cool scratching my head... I opened the cap to at least fill the tank back to the minimal line just in case, considering I had a 20-30 min drive home. I noticed the neck on the tank was warped and the cap would spin tight and then jump a thread n loosen, so I bought a new tank and cap and installed last night.

Which brings me to today. I washed the car and as I finished wiping the excess amourall off the tires I saw a stream of coolant. I opened the hood and the same boiling over from the reservoir tank.

Thermostat is functioning
Fans are functioning
No "milky" presence under the oilcap nor on dip stick
Coolant is pre mix 50/50
Mishimoto 1.3 19lb radiator cap


NOTE: it seems to do it when the AC is on, meaning I've been driving it around without any problems and this only seems to happen when the AC is on, or I am only having the coincidence of it happening when the AC is on..

Ideas?

I'm thinking maybe the radiator cap is bad, but I should always have the problem, not intermittent shouldnt i?...

Am I overlooking something?

 

[F23A1AT]

I think you're right about the radiator cap. I had the same problem. Getting new cap fixed it.

 

[ryan s]

2 cooling system threads this afternoon

rad cap x2. it should be bleeding the excess pressure instead of forcing it into the expansion tank.

 

[MikeyMike]

just drove another 20 min after it cooled for about 30 min and the gauge didnt go a single mark above where it normally runs...

im getting worried about it being a water pump because at the meet Akoutmos mentioned he heard something clicking as it was running next to him... but an intermittent water pump? i know its possible but the odds of it are rediculous

 

[BadgerType]

global warming


its the only connection right?

 

[ryan s]

you could diagnose the clicking by sticking your head under the hood with the engine running, of course. intermittent water pump action would be pretty weird if its loud enough for someone to hear while driving next to you, i'd think its already imploded or damn close.

is your system free of air? positive, double checked after reservoir replacement? has there been any work done to the system recently besides the new overflow tank?

the symptoms say rad cap and they're cheap...but throwing money after problems isn't always necessary so we should cover all the bases first...

 

[MikeyMike]

its been burped again after i put the tank.... and it wasnt driving.. we were sitting in the parking lot he was in the car to my right..

i ordered a new cap from mishimoto caz the oem cap doesnt fit right on the aluminum radiator and rather then make grooves into the aluminum neck id rather wait for the cap

 

[Emo236e]

Hopefully it's the cap or just air in the system somewhere. You are burping with the heater on full blast, correct?

Also, you may want to make sure your thermostat isn't stuck shut (I'm guessing that if it was you would continue to overheat, but the air on the freeway may be cool enough to cool your engine).

The worst case option is that you have exhaust gases coming into your cooling system as blowing air into it forcing it out of the system (overflow is the easiest escape point for it). If you wanted to test for this, NAPA sells a test kit that you put in place of your radiator cap and start the car. It will tell you whether or not you have exhaust gases in the coolant. This happened on a Supra I had and I ended up having to replace the HG.

Best of luck and I hope it's the first few options rather than the last!

 

[MikeyMike]

so i pretty much narrowed it down to only happening when the A/C is on..

ive been driving it around all week with no problems, then today with it being 90 and the humidity being rediculous pretty much making it feel like it was 110 i put the ac on... 10 min later i saw the hot/cold gauge start to climb

 

[JMillerUA6]

Mike, I would check your A/C condenser. Make sure there aren't any damaged fins and that nothing is obstructing it. If everything looks good, then flush it out. I'm pretty sure they sell a kit to do this at the auto parts store.