Low Compression in Cyl. 4 in my 97 Altima

Whats up guys.

I recently removed my engine head to get it inspected since I had to stop driving it about a year ago because my fourth cylinder was pretty much dead. I had someone check the compression, and it was lower than 50. (psi I believe) Anyway, they were telling me that it was probably a burnt valve. I took the head off - which took some time - and looked at the valves on cyl 4, and everything look fine. I guess the other possiblity is that my piston ring on that cylinder is failling, but I am hoping that is not the case. Does anyone have any insight on how to diagnose this problem AFTER the head is removed. I know you can do a leak down test, but you have to have the engine assembled. :banghead: Any insight on other possible problems that cause low compression and how to diagnose them would be greatly appreciated.

Thanks,

You can pour oil into the cylinder, measure how high the level is. Then let it sit for a while and see how much leaks out. You can do roughly the same thing with the head, you might want to use solvent instead of oil.

you have to remove the valves to see if the seat is toast ....