I had previously read multiple accounts of people finding that the 3
fasteners that mount the oil pump (1 bolt and 2 nuts actually) have a
habit of coming loose on the M60 engines. M60s are the V8 engines found
in some of the mid 90's 5 and 7 series cars.
I knew that my 1994 540i has had the nikasil short block replaced with
Alusil (based on the block part number). I therefore sort of expected
that these oil pump fasteners would have been retorqued and lock-tited
during reassembly and therefore would be OK on mine. But I also figured
it was easy enough to drop the lower oil pan and take a gander at the
next oil change just to be safe. That next oil change was last weekend...
Well, I'm very glad that I did check because the bolt was lying in the
bottom of the pan and both of the nuts were considerably looser than the
torque spec. I reinstalled the bolt and snugged everything down to spec
using red loctite, so hopefully it won't come loose later.
A couple of things I found during this job:
One is that the drive chain to the pump was a bit loose. The spec is
10mm of slack and I measured 15mm. The adjustment is supposed to be the
hex things between the pump and the block, but I could not budge them
with an open end wrench but did not want to go crazy with cranking on
them. Has anyone here ever done this adjustment? Maybe I should just
not take chances and put a new chain on there since it has stretched so
The second thing was that the steel oil pan had been significantly
deformed at each of the bolt holes. It seems that somebody cranked the
bolts down (ostensibly to eliminate an oil leak?) and the old style cork
gasket caused the pan to be bent up at each bolt. I was able to bend
the pan back into shape pretty well by supporting the pan with 2x4
blocks and hammering/punching the dents down with a 1/2" x 1/2" x 6"
block of pine. This was required due to the redesign of the gasket. It
is now a steel plate with a neoprene lip on the inside edge. In the
deformed condition the pan would not have even hit the lip and would
have leaked like a sieve. Good thing too because a new pan looks like
it runs a couple hundred bucks.