MC with really low compression

[Bernard Littau]

> Out of curiosity, I ran a compression test on all
> cylinders and the results blew my mind! The best I
> could get out of one cylinder was 40 psi and the
> others were around 30 or so. I was expecting readings
> in the low-mid 100s with an engine with 144K miles on
> it. I was just handcranking the pistons but I did many
> times over. I was planning to do the head with new
> valves and guides anyway, but this soundz more serious
> now. I'll now more next weekend when I pull the head.

Hi Ed,

Hand crank numbers are not comparable.  The compression test must be run
with a strong battery, all plugs out, and with the throttle body wide open.
I think Bentley wants five or ten compression strokes per cylinder, too.
The speed of the cranking has much to do with the compression numbers -- the
faster you crank, the less apparent leakage.

Best,

Bernard Littau
Woodinville, WA
'88 5ktq