crankshaft rear main seal leak

[john daly]

Not a corvette question, but I'm looking at a 2004 GM 4.3l V6 with a rear main seal leak. It's the one piece type. The runout on the crankshaft on the machined seal surface area as measured with an indicator is just less than .003 inches.
Is this excessive ? Can the seal handle this amount of runout ? Is it time to replace the crank? Thanks to all in advance.

john

[Joe L.]

Re: crankshaft rear main seal leak

John-----

I don't think that it's excessive. I think that's probably within factory machining tolerance. In any event, I would expect that it's been this way since the day it was originally manufactured (at GM Powertrain-Romulus). There's really no way that this specification can change with use. The main problem that does occur with the crankshaft seal surfaces is wear and "grooving". If the crankshaft seal surface looks good, I expect that the crank is fine for further use.

[Joe L.]

Addendum

john------

By the way, if there is any damage/wear to the crankshaft sealing surface, there are sleeves available to repair the crankshaft and provide a fresh sealing surface. That's one of the advantages to a 1 piece seal configuration---the sealing surface can be repaired in much the same way as a balancer sealing surface for the front seal. With 2 piece seal engines there's no way to install a repair sleeve. In that case, a special seal with a "displaced lip" must be used. Of course, the latter only repairs "grooving" wear. If the sealing surface is damaged over its entire width, then the crankshaft is pretty much junk.