I have a 93 gs300 with 220,000 miles on it and i recently been experiencing
overheating problems. I bought a new thermostat and installed it and it seems to be working fine but the problem is that even when the car is not overheating, the coolant resevior is bubbling over. I replaced the rad cap and i still hae the same problem. When i was looking at it today, the car was at normal temp and the coolant resevior was bubbling. I then just pushed down ton the radiator cap and the bubbling stopped. Whats going on here? The radiator cap is brand new btw.

 

are you using dexcool err.. "the red coolant"? I did this and my bubbling over into the reservoir went away.(Unless I make a 2.5 hr trip out to las vegas in 98 degree weather.. it acutually overheated to the red, and I had to wait until nightfall to leave vegas.)A little bubbling may occur. Oh I also am using at the moment one of those 35$ NEW Radiators off of ebay temporarirly.

 

Yes i am using dex cool, heat works sporadically meaning it will work and suddenly start blowing cold air. And hows that radiator holding up?

 

I have the same exact situation and about the same amount of miles. I'm in the middle of changing my waterpump to see if that makes a difference. I just hope it's not a blown headgasket.

 

its ok.. as long as I dont take long trips in hot weather (over 95 degrees?) its ok. but I will definitely be changing soon once converted to 2JZGTE. The bubbling still exists when I go for a hard drive and when I park it I can hear the bubbling in the reservoir tank.

 

To see if your head gasket is bad, you can simply wait until your engine is cold, and then open the radiator cap and start the engine. then go and rev the motor from the engine bay and if coolant/water shoots/bubbles out then its more than likely a bad head gasket. If it slowly trickles out then it is no necesarily bad.

 

Sounds like the bubbling is caused by air pockets in the cooling system. Did you "burp" it after changing the thermostat? You can get most of the air out by removing the radiator cap, starting the engine, and letting it run for a bit. It worked on mine.

 

i agree with link13 i had the same problem.. after i replaced water pump, thermostat, and fan clutch i still had that bubbuling prob... so the only thing left was eather head gasket or air pockets...thank god it was air pockets you definetly need to burp it, and youll be ok