I know, depends how you drive, warm up, change the oil etc. but
still,.. is there some kind of accepted ball park figure?
Mine is a 1988 325, 2.7L Auto mostly driven short distances. It just
turned 145k and there is a noticeable knock at cold start idle which
goes away after the temp comes up to normal. The car has reasonable
power, doesn't use excessive oil, runs smoothly and doesn't leave any
Should I resist the urge to add Marvel Mystery Oil?
Interesting. Bearing knock cause by excessive clearance (wear) isn't
really temperature sensitive. If heard at cold start up it usually
disappears as soon as the oil pressure builds up. Until terminal.
Might it be more of a tapping noise than knock? If so possibly piston slap
or tappets which can vary with temperature. Neither of which too much to
Bearings can be checked to some extent by doing an oil pressure check.
*Hard work has a future payoff. Laziness pays off NOW.
Dave Plowman email@example.com London SW
I agree with Dave, here. IME, bearing knock is *less* usual at start
because the oil in the journals is so stiff. When my wife's '77 320i
failed, you could drive it several blocks before it would start knocking.
I'd look at tappets (adjust) and accessories before worrying about things.
Do you have the A/C always on? Compressors knock quite a bit.
That engine can easily go another 100K miles.
For what it is worth: my '90 318i has 280k on the clock, does not use
oil, runs great and have just some mild tappet knocking on startup. I am
more worried that the rust will take her away than the engine fails.
Lighthouses are more helpful than churches. -- Benjamin Franklin
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