E28 Compression Check

["B. A. Leibe" <leibe@xxxxxxxxx>]

I have a 1986 model 528e with 130,000 miles on the odometer.  I performed a
compression pressure test on the engine when at ambient temperature (90
degrees) and obtained some erratic values.  I repeated the compression
pressure test with the engine at operating temperature or just a little bit
below operating temperature and obtained quite different results.

Can anyone comment on the difference in values recorded at ambient and
operating temperature?

It looks like good news that all cylinders at operating temperature yielded
a consistent pressure.  However, the 115 psi is about 35 psi below the
Bentley manual recommendation.  Is this low compression pressure to be
expected on an engine this old?

Can anyone share with me the specific compression test pressures they have
recorded on a 528e?


Engine at Ambient Temperature:

#1    210 psi
#2    140 psi
#3    140 psi
#4    210 psi
#5    205 psi
#6    205 psi


Engine at Operating Temperature:

#1    115 psi
#2    115 psi
#3    115 psi
#4    115 psi
#5    115 psi
#6    115 psi

All comments are appreciated.


Barthe in Houston

------------------------------