Just did a compression test on my 95 GLE wagon with 198000km on it. After the first crank, the pressure was roughly 100psi on every cylinder and then rose from there. How many cranks should get it to max pressure. I stopped at 4 cranks initially getting numbers of (190, 188, 192, 189, 199) but a fifth crank bumped most of the cylinders to roughly 200 with 17psi being the biggest difference (192 and 209 but not on adjoining cylinders)

Is this a normal increase in pressure or should it have risen to max quicker than 5 turnovers? Reading the haynes, what would be considered too high indicating carbon deposits on the cylinder wall? The engine seems to run ok so I'm not terribly concerned but am curious none the less.

 

About 4-5 cranks to get the correct numbers. It should be anywhere from 160-180.

 

so is 200 from an N.A high?

 

200 is a bit high. What prompted you to do a compression test?

 

seeing that they are all slightly high, but all close to each other makes me think that your gauge is slightly off....

 

it's not the best guage out there so that wouldn't surprise me. I did the compression test because last week I couldn't get the car started and wanted to investigate why. It eventually started and appeared to be a fuel problem. Since I bought the guage, I figured I might as well use it and see what my numbers were.

 

i would say that you are prolly dead on within spec. its always a nice thing to see how your compression is anyways, i do it with every new car i buy