compression check on m30

[bahnstormer]

i'm going to get it done this weekend.
since we run 9.0:1 what should i be
looking for? 160ish? i've got a 91 535i
new head gasket, and 150ish thous miles

[Jeff N.]

Anything over 140 is considered acceptable. Look for an even spread with no more than 5 lbs variance across the holes. Make sure they do it warm and hold the throttle plate open.

[Mr Project]

New HG? Was the head milled too? That might give you a little higher compression reading. I got around 170 on my 180k M30, with original HG AFAIK.

The throttle body has a pretty handy little nipple that makes clamping the throttle plate open for the procedure very easy.

I've also heard a 5% variance is acceptable, which would be more like 8-9 psi if you're reading in the 170 range. Just depends on who you ask, but they should be very close together.

[bahnstormer]

ok the guy didn't clamp the throttle plate open....i'll have to do it again
1 - 150
2 - 155
3 - 155
4 - 160
5 - 155
6 - 160

oil pressure is 2 bar at idle and goes up to 6 with revs
all the plugs are nice and clean (with EAT chip)

[bahnstormer]

do u think this kind of compression is ok?

[632 Regal]

Good to go, happy trails!