[s-cars] compression data

[Fred Munro]

Bob;

You are still within spec with these numbers. Compression should be 131 -
189 psig with a maximum difference between cylinders of 44 psig. The wear
limit (rebuild time) is 102 psig.

How many times did you repeat the test? I've found compression testing on
the AAN to be a bit finicky. I count the compression pulses and make sure I
use the same number on each cylinder (usually 10). I repeat the testing 3
times and average the 3 results for each cylinder. I have seen a cylinder
test 130 and then 160 or so on the next test. Of course the ignition
connectors are pulled, the fuel pump fuse pulled, and the throttle held open
during the test.

HTH
Fred Munro
'97 S6


-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com] On Behalf Of Robert Myers
Sent: September 24, 2009 1:47 PM
To: S-Car-List at Audifans.Com
Subject: [s-cars] compression data

*This message was transferred with a trial version of CommuniGate(r) Pro*

Hi Y'all,

I finally got to determining the compression for the AAN engine 
(RS2ed, etc).  I'm a little concerned.

Cyl #	PSI	
   1	165	
   2	150	
   3	130	
   4	150	
   5	130	

These numbers go with the engine which was producing the noises I 
reported hearing a couple of weeks ago - mild exhaust backfire on snap
let-off.

What do these numbers suggest?  IOW, am I staring an engine rebuild 
in the face?

Bob

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