crank bearing replacement with motor in car

["Dan, Marilyn, Anathea & Phillip Patzer" <bmrfamly@xxxxxxxxxx>]

Genetlemen
  I replace crankshaft bearings all the time on Bavaria, E12, E28, E23, E32
BMW's with M30 motors, while the motor is in the car (but turned off).
  Pull the spark plugs for ease of turning the crank.  Get a narrow putty
knife for pushing out the old bearing shells.  I use "STP" etc. to wet the
new bearing shells.  Care must be taken to get the bearing locks into their
grooves, and get the bearing caps on in the proper orientation.
  "MIKE" the crank journals, and the old and new bearing shells.  Don't
trust markings on boxes.  This is a difficult job and you don't want to do
it twice.
(voice of experience)  "Mike" all bearing shells.  I've received sets that
weren't matched. Get a strip of .001-.003" "PLASTIGAGE" and learn how to
read it.  Using "LOCKTITE" on the rod nuts, I carefully tighten to the
lower torque spec, as these are stretch bolts.
  Plan on a new oil pump while you're in there.
  I clean the gasket surface of the motor first, then I start with the rear
bearings doing one-ata-time, and work my way forward as things get drippy
with the new bearings in place.
  The center main bearing has "THRUST" side-walls on it.  This can be
difficult to start in place as the crank moves for/aft when the old
top-shell is removed.
  With careful lighting, and a gentle hand, you can see when the crank is
"centered" within the bearing space of the block, and the shell slides
right in.
  Use the "cardboard" type pan gasket.  The cork ones cause many problems.
  Depending on the engine mileage, this would be a really good time to lift
the head for a valve job, pop the pistons for a clean-up (re-radius the
oiling holes) and set of new rings, with a "glaze-breaking honing" of the
cylinders.  If you hone abd wash-down the cylinders, do this BEFORE
changing the crank bearings so the new bearings will not be contaminated.
  NOTE* On many BMW's it's easiest to anchor the motor from a chain around
a 4x4 accross the fenders, and remove the front subframe to access the
underbelly.  In fact on some models it's not possible to lift the motor
high enough to have the pan clear the subframe, so I'm forced to remove the
subframe.
  If I cannot raise the bridge, I lower the river.


 Dan Patzer the CyberWrench from BIMMERS ONLY Seattle's exclusive BMW hobby
shop
Providing O.E.M. parts, Independent service & Instruction since 1964
 12724  Marine Drive,  Marysville, Wa. 98271
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