I bought a Nikasil 530i back in '03, at a suitably discounted price
given the excellent condition of the body and interior and the
likelihood of engine failure. It ran great for 3 years, but now it's
starting to burn oil when the engine is cold, and the compression is
getting a little lower than I'd like in a couple of the cylinders (6
of them top out around 180-185; the other 2 are down around 160).
There's also a new, high-pitched periodic sound (not really a tapping;
more of a squeak) that varies in period with engine RPM. My mechanic
buddy says it sounds a little like blowby from a shot piston ring, but
that the compression readings seem too high for that to be the case.
Anyway, we're thinking of at least new head gaskets, probably new
valve guides and seals too, and possibly just tearing the whole engine
down and rebuilding from the bottom up. I've been looking for a
machine shop that can bore out and sleeve the cylinders, but my
impression from reading old posts here is that that's a dicey job and
possibly much more trouble than it's worth.
What I'd like to know is whether anyone here has tried dropping a US-
built engine into a BMW. My friend claims that a Chevy 350 ought to
fit in the engine compartment easily, and it would be much cheaper
than buying a rebuilt BMW engine and about the same cost as doing the
rebuild ourselves (probably about $1000 once machining and new parts
are taken into account). Alternatively, we could go to a scrapyard
and pull a non-Nikasil M60 or M62 to rebuild ourselves, which would
presumably avoid the need to do any cylinder work other than perhaps
honing. I'm not very experienced with engine work myself, but my
friend assures me that we can get the job done.
What sounds like the best course of action here?