John,

My manual says "no less than 6 bars", which is about 90 PSI. So I set the line pressure at 100 PSI and it worked fine. One note about the compressed air though: If you're not right at TDC for the cylinder you're working on it will turn your engine over! I didn't want to hover on the brink like that so I turned each cylinder just past TDC and put a breaker bar on the crank nut with the handle against the shop floor. So when I pressurized the cylinder it would try to turn in the correct direction and the breaker bar would hold it in place. That worked well.

__________________
D.H.

04 ML500
02 E430

Experience is something you don't get until just after you need it.