Compression test numbers 87 S4 auto
 

Getting ready to pull the engine for MM/OPG, TB/WP, Refresh..etc..

I wanted to get some base line compression numbers. All are close to each other..
However, here is the range. From 97 to 108..
Car runs great, aren't these numbers off by about 100?

so, what are the compression #'s supposed to be.

I ran the car and had it up to operating temp. Parked it and had all plugs out in 10 minutes. Compression tester in, WOT turned for about 6 turns..

thnx

Get a new compression tester. I would think a good running S4 should be around 170 psi per cylinder. But i don't own an S4.

How was the compression test done?

Warm up the engine to full temp, let it cool enough to avoid burns, but still warm.

Pull all the plugs
remove the fuel pump fuse or relay
hook a stout battery charger to the battery

Have a sheet of paper ready laid out with a chart 1 - 8, and a pen.
Hook up first cylinder to gauge and have helper crank 5 or 6 umphs with throttle wide open, make sure same number of umphs for each cylinder.
Do the next cylinder.

thats exactly how i did it..gonna get a new tester today. I even took mine apart, changed the schrader valves and cleaned it all up..Same results.

New gauge..good numbers

172-783

Did you mean 172-183?

My old 1972 4.2L inline 6 Jaguar motor was within 2-3 pounds per cylinder with a refreshed top end but 176k miles on bottom end.

It had 9:1 compression and was in the 160s..

I will do my 928 soon, the P and original O was an oil changing fanatic.