Compression problems

[ilags]

Checked compression and there are 4 cylinders at 160 psi, and 2 at 60 psi. Any tips for that? is that worthy of a more expensive engine re-build or can i do a cheap individual rebuild?

[US240Z]

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[Ed]

Did you adjust the valves before you did the comperession test?

[ilags]

How would adjusting the valves mess with the compression?

[2ManyZs]

If your valves aren't adjusted right, they either won't seat properly or open far enough to allow the proper amount of air into the combustion chamber, depending on whether they are too tight or too loose.

Next thing you should do is put a spoonfull of oil in the 2 cylinders that were low, and re-test them. If they show higher compression than before, the rings or cylinder walls are the cause as the oil will work to seal the rings to the cylinder walls. If they still show a low compression like before, then you know the problem is either the headgasket, or in the head itself such as the valve seats or valves. Of course, it could end up it is a combination of worn rings and headgasket/valves, but until you check it, you won't know what to be looking for when you remove the head.

How much you have to do will be a result of what you find when you do this test, you may only have to rebuild the head and/or replace the headgasket.

[ilags]

so if the compression is higher after i oil them...do i hafta replace anything?

[2ManyZs]

Probably.....:disappoin

By checking it this way, you'll know how to best save time.

If it checks out better with the oil in the cylinders, you'll know you have a lot of wear in the bottom end (rings and/or cylinder walls) and the best thing to do is pull the entire engine and rebuild it. Probably be best to just go ahead and rebuild the engine from the bottom up, or replace it with a reman engine if you can find one for a reasonable price.

If it tests out nearly the same, you know the majority of the problem is above the block, so you'd only have to pull the head, and only need to rebuild the head by checking it for straightness, doing a valve job, replacing the valve seats and then putting it back together along with a good top end gasket kit.