3 out of 4 bad exhaust valves?

[PiratePast40]

Got a good price on a spare AQ130 so took the plunge. Set it up on the engine stand and found the compression at 185, 85, 120, & 130. Mainfolds are removed and I had been spraying fogging oil in through the plug holes and also on top of the valves the last couple of days so it was well lubed up. Decided to try a leakdown test with surprising results. Number 1 didn't leak by but the 3 low cylinders are all blowing air out the exhaust valves with one of the cylinders blowing out the intake as well. I did the test with the respective cylinders at TDC and even ran a feeler gage under the rocker arms to make sure the valves were shut.

Looking at the valves through the ports in the head, the exhaust valves look pretty gunked up and there is a little oil coming in through the seals. There was no discernable air coming through the crankcase vent while testing any of the cylinders. It turns freely without any scraping noises when turning it over by hand.

PO said the engine was sitting for 2 years.

So obviously, the valves are leaking by but is it common for the exhaust valves to be the major bad actors? Is it likely that this is minor rust on the valves and seats and will clean itself up once the engine runs for a little bit?

(OK - I probably know better on the last question and no - I don't believe in unicorns either!)

Thanks in advance for the help.

 

[Don S]

Re: 3 out of 4 bad exhaust valves?

A compression test on an engine that hasn't ran for 2 years is a total waste of time and means nothing. Fire it up on blocks and run it for a few minutes. Then do another test.

 

[PiratePast40]

Re: 3 out of 4 bad exhaust valves?

Don,
That makes sense and was why I did the leakdown test. I would have expected the rings to be a wildcard that may or may not reseal after running but what about the exhaust valves not seating?