Compression tests can be very misleading and having good compression is
not always signs of a healthy engine with lots of life left. The next
proper step is to do a "leak down" to determine if there is leakage in
the valves or piston rings, and to determine the amount of leakage. To
further evaluate engine condition, the oil pressure needs to be measured
as most sudden catastrophic failures will be there. The low compression
reading on #1 can also mean there is less carbon build up in the head or
on that piston. Do the leak down.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf
Of Matt Sutton
Sent: Wednesday, June 04, 2003 2:14 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Interpretting Compression Values- 88GL?

Hi Folks,
    Did a compression check today, and need some help finding what these
numbers really mean.  Here's the results:
Cylinder #1: 125-130 psi (9 bar)
         #2: 145 psi (10 bar)
         #3: 140 psi (almost 10 bar)
         #4: 145 psi (10 bar)
 Test done per Bentley, car fully warmed up, accelerator floored. Test
tool
was a universal compression tester from NAPA (not easy to use, but
re-checked results for cylinder #1 a couple times.) Cranking/rise times
pretty even.
    Other info: 88GL(manufactured 87), 116k on engine. Exhaust/cat
non-stock, and in poor shape (see later note). There were some long
standing
FI problems, now fixed. 950 miles since last oil change(10w40), very
little
to no oil consumption (have topped off once), and the oil itself looks
pretty clean. Plugs look similar, no fouling. 22.5 mpg on last long
trip,
though this is mostly an urban daily driver (Brooklyn NY).
    I'm shopping for a new exhaust system, and did the comp. test to
figure
if I'd be throwing away resources on a not-long-to-live engine. Right
now
I'm pleasantly surprised by cylinders #2-4, concerned by the unevenness
of
#1. How bad is this? What causes and cures? Which hole do I stuff money
into?
TIA
-Matt Sutton