change headgasket

[jick.cejoco]

My friend's 91 Corolla changed engine to a redtop 4AGE (16 valve high horse) is having some very minor problems. Amoy gasoline fumes yun radiator and overflow tank and small bubbles can be seen in the radiator. This is a sure indication of leaking headgasket on the exhaust portion. in a weeks time mga 1 glass of water yun nawawala sa radiator nya although never pa naman sya nag overheat.

inadvise ko na topoverhaul, pero yung mechanic nya insisted na change headgasket lang daw. pwede bang headgasket lang palitan pag ganun?

badtoy,
if the engine was running, the compression in the cylinders could reach up to around 200 psi versus the cooling system of 0.9 kg/c.m2 or 13 psi. but once the engine stops, the pressure in the cooling system is higher than those of the cylinders assuming the radiator cap is intact and the engine is in the cool down phase. if bubbles were noted in the cooling system, of course it is a telltale sign of compression leak. but with this, the oil filler cap would also show motor oil emulsifying (vanilla shake looking thingy). maybe the gasket is bad or the gasket was not torqued to specs. the ten cylinder head bolts for your engine are plastic bolts or plastic region bolts or sometimes called torque to yield bolts. when you install these bolts, you follow a sequence and in stages with the torque wrench. then you will be instructed to turn an additional 90 degrees or two of rotation, again, in sequence or you are back to the same situation.
jick