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1998 BMW 740 Repair Question


Topics covered: Engine, Compression, Abs.
Mileage: No information provided.

Asked on June 2, 2010

1998 BMW 740 engine vibration

Engine Performance problem
1998 BMW 740 V8 Two Wheel Drive Automatic 285000 miles

I have a 1998 BMW 740iL with hijgh mileage. The idle is bad causing car to vibrate an it has a rich exhaust smell. Compression test reveals that all cylinders but one( number five is reading 150. But number 5 is reading 75. If this helps, the service engine light stays on constantly in yeloow and the asc/dsc light and abs light is on all the time.

Already replaced spark plugs.
Avatar Asked by jt1966

Answer

Replied on June 2, 2010

Hi there,

The low compression is a big concern, i would first get a wet comp test done as this swill help determine weather it is rings or calves at fault, also a scan to read the unresolved fault codes.

mark (mhpautos)

Tiny Answered by mhpautos (expert)
26,915 answers provided
Replied on June 2, 2010

Thanks for the quick response and help. Should I be considering an engine rebuild. or for that matter an engine?

Tiny Response from jt1966
1 question asked
Replied on June 2, 2010

Hi there, i feel that at the mileage you have a top end o/haul will be fraught with danger as this will load up the lower end, i would be considering a full o/haul or a re-co long engine, but a wet comp test will tell us a lot and i would also get the valve clearance checked as a tight valve can cause this as well, best to know exactly what we are looking at first.

mark

Tiny Answered by mhpautos (expert)
26,915 answers provided