Compression Test Results -- AQ 140 A

Yesterday afternoon I decided to attempt a compression test on my "spare" V/P AQ 140 A engine.

Here are the results:

# 1 Cyl Dry 80 Wet 120

# 2 Cyl Dry 180 Wet 185

# 3 Cyl Dry 150 Wet 150

# 4 Cyl Dry 160 Wet 165

Please comment on these values. This is the first time I have done this sort of thing.

Many thanks.

Sincerely,

John Lofquist

At first glance the piston rings are worn or seized in #1 cylinder. I would do a leak down test and find out where the leak is in that cylinder. Basically, you need to put #1 piston on TDC and the end of the compression stroke, then pressurize the cylinder with compressed air and hear where the air is leaking by. You can buy a leak down tester or you an make your own. In your case, since the leak is obviously severe, you just want to pinpoint where is taking place, not the rate. The cheapest way would be finding a fitting with the same thread as your spark plugs (an extension hose for a compression tested would work), connect an air hose to it and pressurize the cylinder the way I said. If you hear air going into the crankcase, then you need to pull the piston and rod and see what the problem is. Installing new rings is cheap, and a new (or new to you) piston won't be expensive. However, if the cylinder walls are worn, that is a different story. In that case you may be better off getting a B21 based volvo engine from a car wrecker and marinizing it.

Dear El_Pescador,

Thanks for your insight and commentary.

Please excuse my question .... but I am unfamiliar with the notation ... what is "TDC" ? ... (I'm assuming it's not The Discovery Channel !! )

Sincerely,

John Lofquist
Beaver, Washington

If you find a way to watch The Discovery Channel in your engine, you should patent it!!!

TDC stands for Top Dead Center, which is the piston being placed at the end of the compression or exhaust strokes. In your case, you need it at the end of the compression stroke.