Chuck,
I downloaded the pdf file from the Clevite site that
you mentioned. One thing that struck me was a paragraph about the grinding
marks left on the thrust face after the crank is ground. I copied it
here:
SURFACE
FINISH
Crankshaft thrust faces are
difficult to grind because they are done using the side of the grinding wheel.
Grinding marks left on the crankshaft face produce a visual swirl or sunburst
pattern with scratches sometimes crisscrossing one another in a crosshatch
pattern similar to hone marks on a cylinder wall. If these grinding marks are
not completely removed by polishing, they will remove the oil film from the
surface of the thrust bearing much like multiple windshield wiper blades. A
properly finished crankshaft thrust face should only have very fine polishing
marks that go around the thrust surface in a circumferential
pattern.
I remember asking the guys at both machine shops I
dealt with about the pattern on the thrust face the first time I pulled the
engine out. Everyone said it was no problem, they all get put together that
way. I took them at their word��.WRONG.
I polished the marks off the thrust face with 600 grit
followed by 1200 grit. It took me about an hour but I got it looking
beautiful. I put the motor together and it doesn�t look like it is grinding
the bearing anymore. I still had a slight amount of residue in the oil filter
after running the car but 2 filters later there is virtually nothing polluting
the oil. I�m sure there was a good amount of �gold dust� hiding in the motor
that needed to be cleansed. I just changed the oil again to be
sure.
You can bet that I will never build another motor
without paying particularly close attention to the thrust face of the crank. I
hope sharing my experience here prevents someone else from having the same
problem I did.
I printed copies of the Clevite tech article for both
machine shops I deal with and I highlighted the Surface Finish
paragraph.
Thanks to everyone who took the time to help. This is
a great forum with an awesome knowledge base.
I�m going racing. I believe the problem is finally
solved.
Bill Vander Werf
-----Original
Message-----
From:
[EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
On Behalf Of Chuck
Hanson
Sent: Monday, December 30,
2002 4:13
PM
To:
[EMAIL PROTECTED]
Subject: Re: [Chevelle-List] Thrust
bearing failure
Bill,
Sorry to hear
you're still having problems with the thrust bearing on your engine.
It's a real stumper, I know. One thing that comes to mind is
calling the tech line for the manufacturer of your bearings. They have
probably come up against this problem in the past and may be able to shed some
light on the problem. Sometimes even the most astute engine builders
and/or machinists can overlook something or have never encountered a problem
such as yours. When we talked about your engine a while back I ran over
all the scenarios in my mind, and it seemed like you'd already tried to
correct all the suspected problem areas.
I checked the online tech
site for Clevite bearings (Dana Corp), and there's a lot of info on how to
troubleshoot your problem. Rather than cut and paste that info, here's
where to go:
http://engineparts.com/Motorhead/techstuff/bulletins/TB2043.pdf
Good
luck, Bill. If that doesn't work, a phone call to their tech line and a
conversation with a real person may be the only answer. Sorry I don't
have their tech line # in front of me right now. If you don't find it
yourself, holler at me on the ACES Hotline and I'll try to come up with it for
you.
Chuck
