Low compression
 

Hey, I'm a early 911 guy but a friend with a '99 boxster was having a problem with running rough and a compression test showed all three cylinders on the right bank ( passenger side ) were @ 30 lbs. I pulled the motor out today and am getting ready to do a leak down check but is there any common problems or anything in particular I should look for first? I was thinking head gasket maybe, but all three cylinders is unusual. I pulled the valve cover off and everything looks fine. All the fluids were fine with no coolant in the oil. Any ideas?

Thanks.

Camshafts still in time? Set it at tdc and pull the green caps, the notches in the cams should be parallel with the head. sounds like it jumped a tooth, common of a ims bearing that is very loose.

thanks, i will check that. the chain on that side does appear to be tight though.

the tensioner still works so it will be, but if the ims can flop around when its running...

Hi, just jumping here, I am curious about the leak down test and what might be considered 'good' numbers' for results? I am about to have that done on my 2001 S 986, and I'd like to know what to look for in terms of good vs bad, or acceptable vs not (if that makes any sense). Thanks!

main thing is consistency. anything less than 10% is good, but you want all cylinders pretty close to same. Any reason your having it done? cylinder sealing is not a big problem on these motors...

haven't got around to doing anything yet. just sitting in the corner of the shop waiting.. lol..
All I know is the right side compression levels on all three cylinders were about 30 PSI..