Reservoir tank overflows... - Toyota Nation Forum : Toyota Car and Truck Forums

MattInLA · 02-18-2011, 08:38 PM

1996 3.4 2x4 4runner...odd problem where my coolant reservoir keeps overflowing, bubbles a lot when the car is turned off, never overheats, this is a rebuilt engine, (not sure how old the radiator is...) so my engine rebuilder says "the radiator cap cannot hold the pressure" so he gave me a 1.3 cap vs. standard 0.9 whatever these numbers mean.... so again, I am overflowing water out of the reservoir....fan runs fine, wh is this happening could the radiator be clogged? Never overheats....comments!

kball · 02-19-2011, 11:09 AM

Could be a head gasket. Cylinder compression getting blown into the coolant system. If the new cap is the right one and it's blowing by it I would think it's the head gaskets. If something were clogged it would overheat.

MattInLA · 02-19-2011, 11:59 AM

Hmmm....Engine replaced already had a blown gasket back then got a CEL on a cylinder filled with water, misfire, no this isn't happening.........

jetwhine · 02-20-2011, 12:02 AM

MattinLA,

This sounds too me like you have T-stat not opening very far. And instead of overheating the water pressure gets too high from the restricted flow, and the cap does its job and relieves the pressure, ond out comes the coolant into the overflow bottle. And it won't overheat until the coolant is gone.