"since the difference between good and bad is minimally only .020"..."
Peter,
I'm not quite sure if you're referring to the .002" difference between max
and min of recommended crank endfloat (.006" minimum, .008" maximum).
Whether it is or not, this is a pretty difficult judgement to make without a
dial indicator, no less while checking with the engine in the car unless
you've got the right extensions and a magnetic base. Discerning 0.006",
0.008" or 0.010" endfloat by feel is a crapshoot, IMHO, and if excessive
endfloat can be so obvious as to be sensed by feel than it's likely a good
bit more than the .008" max specified. Standard inkjet printer paper is
about 0.004" thick - you're being asked to make a call on good and bad
endfloat within half that amount. Some listers may be deadly accurate with
feeler gages but .002" total range is a bit too tight for my feeler gage
skill level.
If excessive endfloat is a serious concern I 'd recommend dropping the pan,
removing the rearmost main bearing cap and sliding the two washers out.
This will give you a chance to examine the crank thrust faces (the front is
really the one that takes the beating due to clutch actuation load) and
measure the thickness of the two washers. As the front gets most of the
wear the rear washer should be thicker to some degree if the washers have
been there awhile. I can't recall the exact thickness of standard thrust
washers (.0925" maybe) but they were the same thickness when new. However
all of this goes out the window if a PO installed oversized washers and they
are now very worn. Hopefully someone knows the exact thickness for a
standard thrust washer.
With the pan off and one main bearing cap removed you might as well check
the main and rod bearings and oil pump internals for evidence of wear or
scoring. If the knock is due to one of these areas it should be pretty
obvious.
I recently found myself in "no man's land" at .010" endfloat during the
rebuild of my own motor. At best, with both at +0.0025" oversized I would
be at .005" endfloat (too tight), while with one at +0.0025" and one
standard I would be at 0.0075" (just below the .008 max, not where I really
want to be on a new motor). The solution was to grind 0.0015" off of the
steel back face on one of two +.0025" washers, using a surface grinder,
putting endfloat at 0.0065". All of this was done during the rebuilding
process, checked with a dial indicator on the front nose of the crank and
then on the counterweight as shown in Bentley 12.21.26.
Greg Dito
CD6250L
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