No start

ANTIKYTHERA

MEMBER
2002 BMW X5
3.0L
6 CYL
4WD
AUTOMATIC
160,000 MILES

Working on the car listed above. Would low fuel pressure replace the fuel filter in the fuel pump restoring the pressure but still won't start. Check the timing chain it's intact and still rotating the cam. Did a compression test not get any more than 30 to 60 PSI on any cylinder. My question is is I've heard some of these engines are notorious for the oil pump sprocket bolt falling off would low oil pressure cause a hydraulic lifter to collapse preventing the valves from opening and closing causing low compression?

Friday, June 21st, 2019 AT 4:17 PM

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

Hi,

Low compression does seem like it is your issue on this M54 engine. However, I have not seen the oil pump sprocket falling off causing low pressure then a lifter issue, then a no start due low compression. Normally, that gear doesn't fall off all of a sudden. The nut normally comes off and the engine starts running very poorly due to low oil pressure causing lifter issue.

Has the vehicle been sitting a while or not run in a little while?

Here is a video of a more common cause of low compression on these engines:

https://youtu.be/NtsKiKWeoa0

If this is not your issue then you will need to run a leak down test to try to determine if the engine is sealing and if not, where you are loosing your compression.

Here is a picture of how the nut will fall off the oil pump gear.

Let me know what you turn up with this video or the leak down test and we can go from there.

Image (Click to make bigger)