My 95' toyota 4runner's engine is overheating so badly that it is causing the antifreeze to boil, and steam out the overflow tank. It has a rebuilt engine and a loose vacuum hose do you know what the problem could be??? It has a V6 enigne with 4wd

 

Maybe fan clutch, radiator water pump or head gasket. I wouldn't let the 3VZE overheat fro too long because if it isn't the head gasket it will be eventually.

 

thermostat maybe.

 

good call, I forgot about the thermostat.

 

Does the idle change at all before/while overheating?

 

samething happened to me, and yes it was my headgasket

 

First thing do a pressure test on the cooling system!!!

I have seen radiator cores blocked cause this problem.

Also air pockets in the cooling system can do this also.

Pressure test go from there.