Here is a problem I don't understand. My 4 cylinder volvo penta AQ151C engine quit running the other day. (It's the same basic engine that was used in countless Older Volvo Cars over many years) I thought the problem was the head so I got a rebuilt one and put it back together. It seems to be doing the same thing:
The motor won't start. I did a compression test and When I turn it over it it makes compression for about 5 or 6 revolutions, then for about another 6 revolutions it makes zero compression. This make no sense to me whatsoever but I suspect the problem is in the lower end due to the head rebuild.