Mechanics

COMPRESSION TEST MYSTERY

1989 Volvo 240 • 100,000 miles

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.

Anyone have any ideas what is wrong?

Thanks,

Jim
Avatar
JimS88
July 17, 2012.




Inject air in the cylinder to see where the leakage is coming from.

Valves seating ok?

Roy

ASEMaster6371
Jul 17, 2012.
MAYBE I THINK INTO THINGS TOO MUCH

ARE YOU SAYING IT BUILDS COMPRESSION 1ST FEW REVOLUTIONS----THEN IT STOPS BUILDING PRESSURE (IT IS TOPPED/MAXED OUT) THE NEXT FEW REVS DOES NOT IMPROVE YOUR READING?

IN OTHER WORDS. DO YOU THINK IT IS SUPPOSED TO KEEP PUMPING UP MORE AND MORE AND MORE ON EACH REVOLUTION?

I DID READ THE QUESTION SEVERAL TIMES.I'M NOT QUITE "RAINMAN" MATERIAL YET!

THE MEDIC
AD

Tiny
CJ MEDEVAC
Jul 17, 2012.

AD