change headgasket

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?

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Originally Posted by badtoy

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?

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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

Thanks jick for the reply. I do not see any signs of water in the motor oil. Its still oily to touch and black as it hasnt been oil changed for about 3 months. Radiator water is also clear with no indication of oil.

We will try to have a compression test. But getting back on my question, whether it fails a compression test or not with the symptoms on hand (small bubbles in radiator and gas fumes in water) can this be done only by replacement of headgasket?

Quote:

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Originally Posted by badtoy

Thanks jick for the reply. I do not see any signs of water in the motor oil. Its still oily to touch and black as it hasnt been oil changed for about 3 months. Radiator water is also clear with no indication of oil.

We will try to have a compression test. But getting back on my question, whether it fails a compression test or not with the symptoms on hand (small bubbles in radiator and gas fumes in water) can this be done only by replacement of headgasket?

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badtoy,
yes and no. if it's only the gasket that loosened up or rusted, yes. but if the cylinder head is corroded from water electrolysis (if you did not have the protection of the antifreeze/coolant), then you might even have to replace the head. with that operation, you might as well (MAW) have a top overhaul done; i.e., replace valve stem seals, grind or lap the valves, replace the oil seals and the timing belt.
jick

check the cylinder head first,, yung warp niya tnx

ok i think its still best to open up the cylinder head and have the necessary parts ready.thanks a lot again.