Date:         Sun, 15 Dec 2002 20:46:03 -0600
Reply-To:     Stan Wilder <wilden1@JUNO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Stan Wilder <wilden1@JUNO.COM>
Subject:      Re: Top Overhauls
Comments: To: j_rodgers@CHARTER.NET
Content-Type: text/plain; charset=us-ascii

At the time of a top overhaul, a crankshaft runt test would be made with
a dial indicator to determine the amount of wobble in the crankshaft. If
that check was in spec, then the case was left intact. If not, then it
was time to crack the case for overhaul, and that would include the case
and all internal components.
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When dealing with a 4000$ crank I've seen them chrome plated to bring
them back into specs.
Some aircraft came with chrome cylinders and that was a standard process.
Although I think the chrome cylinders tended to run a little hotter.
In VW engines the #2 main bearing can be worn more than the #1 or #3 and
your crank can be in near perfect alignment. Its just the way the bearing
is loaded at high RPMs that causes excess wear at this point.
You couldn't measure this wobble on a cold crank ........... it only
deforms / bends under heat and stress.
When crankshafts are set up on a grinding machine they are measured for
straightness before the grinding process is started. In effect a bent
crank could be machined back to tolerances if it is out only 2/3
thousandths.
In short; there really isn't a good way to evaluate your main bearings /
crank without splitting the case and spinning the crank between fixed
centering arbors.
In any event that your engine lost oil pressure immediately, I'd split
the case. If the oil pressure edged down slightly over several thousand
miles I'd investigate the rod bearings for abnormal wear on the #2/#3 and
be wary of the mains.

Stan Wilder

Stan Wilder

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