Date: Tue, 3 Jan 2006 12:18:13 -0800
Reply-To: Björn Ratjen <Bjorn@IGLIDE.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Björn Ratjen <Bjorn@IGLIDE.NET>
Subject: Re: Failed Crankshaft seal yet again
In-Reply-To: <113629853001@mx-4.vancouver.ipapp.com>
Content-type: text/plain; charset=iso-8859-1; format=flowed
David,
As I know how frustrating these things can be let
me wade in with some comments. The seals are made
to keep oil from wandering along a smooth and
perfectly round surface. They need to stay in
place and follow the moving surface in an
absolutely straight path. If the matching surface
is either not completely round or wobbles then
the seal will break. You can look at the surface
of the moving part. Is there one (or two matching
the lips of the seal) straight line?=good. Does
the line have differing thickness or is it not
completely straight?=bad. Wobble can occur
through deformation of the moving part,
misalignment of mounting surfaces (crankshaft to
flywheel) or excessive play in bearings. Look
also for evidence of movement of the seal in the engine block.
When the seal is installed it needs to be tight
and straight in the engine block. Only press on
the outer ring for installation. Check for any
rough parts or burrs in the moving part which
could damage the seal during installation. The
seal actually creates a small indentation in the
moving part over time. Check this indentation
carefully for any tiny imperfections and measure against seal if necessary.
Also check pilot bearing for transmission shaft
(in flywheel) as too much play can damage transmission seal and oil clutch.
I do not know what you mean by "catastrophic"
failure. A small leak can drain a lot of oil. I
remember when I spent a day to help a friend to
replace his aircooled van engine (at a parking
lot) with another one a friend of his had stored,
only to find that all the oil drained within
50kms because the crankshaft seal had simply
dried up. We bought a tow bar and I towed him
300kms on the German Autobahn with my VW van
through the night. As he had a 1600cc engine and
I had the new! 2000cc engine he found it to be
almost as fast if he had driven on his own power. :-)
Hope this helps.
Björn
At 06:25 AM 03/01/2006, you wrote:
>Date: Mon, 2 Jan 2006 23:47:14 -0800
>From: David Shepherdson <shepherdsond@METRO.DST.OR.US>
>
>I just watched my 87 syncro Westfalia being winched onto a flat bed tow
>truck for the 3rd time in 5 months near Bend Oregon this weekend, all
>three times were the result of catastrophic failure of the main
>crankshaft oil seal. I am appealing to the list now to solicit some more
>ideas about what could be wrong before I drive back to Bend (from
>Portland, Oregon) next weekend to try and fix it. The first time this
>happened was on a trip to NWT in Canada. That time it was the part of
>the seal that contacts the flywheel that ripped. The next time the
>break was on the face of the seal (hence the hypothesis that the seal
>had been rubbing on the flywheel (although it did not appear to stick
>out - the replacement was very well countersunk), of course I don't yet
>know where it has failed this time. I do however know from looking back
>through receipts from the previous owner that this 40k engine has now
>had 6 main seal failures in its life. My current hypothesis from
>talking to mechanics at VW is that there is something wrong with the
>flywheel (it looked OK but I did not check the diameter of the sealing
>surface) so I have a freshly machined replacement from AVP to replace it
>with. Needless to say the O ring was replaced each of the last 2 times
>and I also checked the end play last time which appeared to be well
>within limits (I will measure it again when I dismantle it next
>weekend).
>
>Both the last two times the symptoms have started as soon as the engine
>was reinstalled. Oil leaked from arround the bell housing from day one
>after replacing the oil seal. Not a huge amount but enough to spot the
>rear door after freeway driving and leave a daily oil mark on the
>driveway. This suggests that the seal is under some sort of stress
>right from the start. Then after about 2000 miles the seal fails
>completely and all the oil drains out. I guess if the flywheel diameter
>was too small it could cause a leak but why the seal then fails
>completely I dont know. I am wondering if there is anything that could
>cause the oil pressure to be too high in this area (faulty instalation
>of bearings??). Or does anyone have any other ideas - I am at a loss
>now and if it starts to leak again after I replace it this time I will
>have to replace the engine. Unexpected catastrophic failure of the oil
>seal is just not something I can live with (it makes me shudder to think
>of some of the places I have been where this could have happened). All
>ideas gratefully received!
>David
>