Water Boiling In Reserve tank
 

Water Boiling in reserve tank.
I have a 87 Toyota Supra with the 7mgte engine in it. Lately it has been overheating whenever I drive the car. I can start it and let it set there and let the temperature gauge come up to its normal reading and it does not overheat. But when I drive it a couple of miles and then check it I can hear the water boiling in the reserve tank. I pulled the stem out of the reserve tank and steam was coming out of it. I Have recently replaced water pump, thermostat, and radiator cap. Also the cooling fan comes on. Any help would be greatly appreciated.

Thanks in advance

CAVEMAN62

Hmmm... are you losing any coolant? Have you taken a good, close look at your oil dipstick and the oil on it?

I'd have the system pressure tested to see if you've got a coolant leak in a hose somewhere, or substantially worse, a blown head gasket with the coolant leaking into the cylinders or into the oil system. It's also possible that you've got a partially blocked radiator. Is your coolant nice and clean?

In any case, the less you drive it until the issue is resolved the better off you'll be. 7M's don't like being overheated. To quote another Supra owner I've heard about, "A turbo Supra is an unforgiving bitch at the best of times.".

Water Boiling In Reserve tank
 

Hi! , Had the same problem even after I had repaired my BHG . The problem was the radiator cap . The cap would release pressure at 0.9 Bar , but would continue to blow all the way to 0 ( zero ) even when cold tested . ( this is the best way to test as the cap can be safely removed after pressure released without scalding ) . I rigged up a tube from the radiator overflow into a bucket of water . when the cap released pressure bubbles would show and only stop when the cap had resealed . This should be around 10 PSI .
I also checked the timing , being slightly retarded would make the exhaust hotter than normal and this would heat the water further .