Previa Boiling Over

[2autumn]

My Previa has just boiled over again! It first did this 3 years ago in 2001. I refilled it with water and it still boiled over again about a week laeter. I installed a new thermostat and everything was okay for a year. then is summer of 2002 it boiled over again. I replaced the thermostat and everything was okay for the next two years until today. It was 100F outsdie today and the car boiled over again.

Each time that I have replaced the thermostat, I have retested the old thermostat and each one has opened at the same time and temperature as the new one, suggesting that the thermostat did not need to be replaced?

I cannot get it to accept any new water into the system, it just wants to push it out. The Heater initially blew very hot, but now blows cold, suggesting that there is an air bubble in the engine block.

I jsut drove a 2000 mile round trip this week and everything on the car was fine, it has only done 120000 miles.

What do you think my problem is? My opinion is that it just got too hot, pushed some water out and developed an air bubble that prevents me from refilling it.

Maybe this time, I should just try to drain all the water out, and then refill it?

What do you think?

Does anyone else have this recurring problem. Normally the engine temp gauge sits in the middle of the gauge. I doubt that my head gasket is leaking which is about the only other cause that I can think of?

[2autumn]

Okay, I found the problem. One of the risers in the radiator reserve tank was blocked. Cleaned it out with a thin wire and lots of water.

[blobstrom]

Its also worth backflushing the radiator as well