Wombat

Troublshoot low compression + oil leak after cylinder head replacement

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Wombat    0

I recently fitted a reconditioned head, complete with VRS kit to my 2000 1.8ltr (7A-fe) Corolla following a blown head gasket.

The engine starts but forces oil out the rocker cover and/or cam seal at the timing gear end into the timing gear/belt housing (between a and b in images provided)

Also, i have only 60 psi compression in cylinders 2 and 3. 1 and 4 have 180psi.

What are likely causes? How do i correct these problems?

Piston rings??

Please advise

 

IMG_201708243_120115.jpg

IMG_201708243_115241.jpg

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With the top cover sealing, the Toyota manual usually recommends some of their grey or black sealant to be installed in those corners by the cam ends.

Cylinder pressure is very low at 60 psi but not on all cylinders...Only on one phase of the firing order.  Do you have a reading from before the head was rebuilt?  Why was it rebuilt? Just wondering if its rings, because if your engine builder did a good job on the head, and the valves seal then its gotta be the rings?

Cam timing error might cause even lack of compression, carrying the same misalignment to each cylinder equally, so possibly eliminate that.  Just double check your marks to be safe.

 

 

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Wombat    0

I blew my head gasket. Engine overheated but only for a minute. I fitted a reconditioned head. Cam timing marks are properly aligned.

 

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altezzaclub    196

Sounds like a head gasket problem, letting compression through between two and three.. Very odd... I wonder if they pressure tested the reco'd head.

Unless the rings in two and three are destroyed and letting the compression passed into the sump, which would give you major blowby and push oil out the top cover seals... 

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is it possible to fit the head gasket backwards? not familiar with the engine but can be done on others and causes issues. Just a thought. 

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altezzaclub    196

Nah-  All four sides are completely different to each other..   Not much space between the cylinders though, just a little strip of metal.

 

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ke70dave    202

As others have illuded to, the fact that the centre two cylinderes are very low, and the others are fine suggests that something is wrong between cytlinders 2 and 3.

Unfortunately about all you can do is remove the head again and see what is up. did you check the block for flatness last time? just a straight edge will do.

 

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KE70ph    0

Try compression test on 3 and 4, (wet test procedure) pour a small amount (enough to cover the cylinder wall) of oil into the cylinder through the spark plug hole. 

- if adding the oil increases the compression, the piston rings and/or your cylinder bore may be worn or damaged.

- if the pressure stays low, a valve may be sticking or seating improperly, or there may be a leakage past the gasket, valve oil seal. 

 

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