I previously reported low compression in cylinder #2 relative to the other cylinders. We did have the engine running fairly well, at least on four cylinders (most of the time) and with a decent idle speed. As you can see, compression in #1 (one blue finger) was 150 psi and 125 psi in #2. This difference across cylinders is just out of range for a healthy engine.
Low compression can be caused by air leaking around the valves or the piston rings. The differential test is a squirt of oil into the spark plug hole: compression would increase if the rings were worn as the oil would form a temporary seal between the rings and cylinder wall. No change would indicate air escaping around a closed valve. We added a bit of oil to cylinder #2 and found no change in compression.
I decided to try a valve adjustment on the hope a maladjustment was causing a leak. Above on the right is the valve train exposed. You can see the push rods on the near side. On the left is a closeup of the two valves for one cylinder. The idea is to set the clearance between between the rocker arm and the spring to a specified distance. The blue gloved hand is holding a measurement gauge that slips between the parts. To change this clearance, one turns the nut on the top of the push rod.
Did the adjustment procedure work? Yes and no. I was able to raise the compression in cylinder #2 from 120 to 125 psi and reduce some of the valve noise. It appeared that most of the clatter was coming from cylinder #2.
What to do? The engine ran well enough, but I was concerned by the low compression and valve noise. Was there something going on? I decided to leave well enough alone and move on to the oil leaks, of which I had many. You can see oil collecting on the oil pan bolts. A good place to start.
Sunbeam 