Low compression on cyl#2

[91 Turbo Mitsu]

My 91 GST has low compression on one cylinder and was just looking for a second opinion. I did a compression test and then dropped a few drops of oil in the cylinder and rechecked the compression with no change at all. I think it might be a valve problem because I have oil blowing out of the valve cover filler cap every time you drive. I plan on trying to do a leak down test to pinpoint but I just thought I would ask for a second opinion from everyone. The only reason I say plan on trying to do a leak down test is because I blew my back out and I am kind of laid up. Thats why I thought to ask for advice. Thanks in advance for any advice as to direction . Travis

 

[Coup D E'Tat]

How low are we talking here? How much oil did you add? A few drops probably won't help.

But yea, a leak down test is where you go from here.

 

[91 Turbo Mitsu]

Its bad. Down to about 30 lbs. I put 3 or 4 good drops in with a squirt can and there was no change. I have another motor but if it is the head why change the whole thing . Although I probably should because I dont know how many miles are on the motor in the car. I will do a leak down test and let everyone know. Travis

 

[fourreGsixty3]

Check how much the Vfaq compression test recommends for oil, but if its down to 30, then I truely doubt a few drops will help. Do the leak down test, and post back, but there is always the possibility that the #2 cyls rings are toast, and need replacing.

Dustin

 

[1997GST]

I say add more than a few drops of oil. Try a teaspoon of oil if it's that bad, won't hurt it. Down to 30psi, you must have a chipped valve. If you have access to a compressor than it's easy to do leakdown. Take the hose off your compression gauge, remove the check valve. Set to 50psi and listen around.

 

[91 Turbo Mitsu]

Thanks to all but it doesnt mater now. I fired the engine to let it warm up to do test and after a minute the oil pressure skyrocketed and blew the turbo seals. I am in the process of pulling the motor and swapping in my spare and I just picked up a t3/t4 turbo. Travis

 

[91 Turbo Mitsu]

Just thought I would throw this out there and let everyone know what I found. Pulled head and number 2 cyl has a hole in the piston so I will be pulling the motor and slapping in my spare motor with a new t3/t4 turbo. Thanks to all and will be back running soon. Travis