[Vwdiesel] Banana Rabbit--Bad news...

[Val Christian]

I had an 84 Rabbit which slipped the cam sprocket.  I was getting off the 
expressway, and just pulling out of the stop sign.  No thunk, no noise,
except the other vehicles honking at me to get out of their way.

Farmer friend was done with the girls for the afternoon, so he came and towed
me home.  I found that there was some movement of the crank, but there was
definitely interference.  So I pulled the head that evening.  Two bent
valves, and one somewhat dinged piston, the other just nicked.

I replaced the valves, and all the valve seals etc while I was at it.
Put it back together and continued to run it for years.

I have seen a VW diesel, where the valve broke, and embedded itself into 
BOTH the piston and the head.  I didn't get the full story on the 
symptoms, but it sort of fits your description.

Either way, they are normally fixable.  We'll all wait to see what 
you find.



> 
> Well, if you get off with just changing the belt you'll have to change your
> email to LuckyDavevw at yahoo.com  .
> Personally, my line of attack would be to pull the cam, then turn the engine
> over and see if one cylinder is leaking excessively, or if you hear a lot of
> whooshing in the intake or exhaust when you rock the crank.  Another way
> would be to use a leakdown tester, just let the piston bottom when you
> pressure each piston up, watch for the turny bits as the piston goes to the
> bottom. It's the surest way to check for valve collision damage.
> 
> But, the crank stuck with accompanying noise event at TDC screams foreign
> object which could be solid or liquid.  Glow plug tip fall off? Oil build up
> in the intake, then get slurped in?
> 
> ...Insert brief interlude....
> I got called away for a few hours, I like Loren's valve clearance checking,
> but I do like checking for leakage, and it's an easy leakdown test when all
> you're looking for is valves, and they are all closed, or supposed to be.
> Turning it over with the glow plugs out is easy, and would be informative if
> you can find a clunk.
> 
> I've stripped the cogs on a belt too.  Crank sprocket just eats them off
> when the motor hiccups and it all starts to rattle, never had one go
> kachunk, but it was uneventful. Quite the tense few hours until I had it
> running again however.
> -james
> 
> -----Original Message-----
> From: vwdiesel-bounces at vwfans.com [mailto:vwdiesel-bounces at vwfans.com] On
> Behalf Of Dave Cook
> Sent: January-30-11 9:37 PM
> To: VW Diesel Group
> Subject: Re: [Vwdiesel] Banana Rabbit--Bad news...
> 
> Didn't think of stripped cogs.  Dangit!  The cheap car may have just turned
> expensive!
> 
> To clarify, I wasn't turning the engine with the cam bolt, I used the
> sprocket hold tool to attempt to turn the sprocket.  I didn't put much
> pressure on it, I just wanted to see if it would turn backwards.  I figured
> if a piston was touching a valve in one direction, it would be able to turn
> backwards the other direction a little bit.  It did not but I may well have
> been wrong in my assumption.
> 
> I think I will be optimistic and say that maybe since the engine wasn't
> running at a super high rpm that I'll be lucky and it will just need a belt.
> 
> 
> Lets assume I pull the belt and find that the cogs stripped.  I then pull
> the valve cover and loosen the (intact) cam so all the valves close.  =
> 
> 
> If I am lucky and the engine can turn over loosly and freely, do you all
> think I could get away with trying to retime the engine with a new belt and
> see if it'll run?  Will there be obvious signs that a valve bent for sure to
> look for?  (from above) If it runs, would you go ahead and drive it?  I
> guess I'm saying, is there any way I might possibly get lucky and not have
> to pull the head?
> 
> Interestingly, I noted that the TDC 0 is right at the center of the
> inspection hole.  Actually, I suppose it isn't that crazy.  I guess that
> means my likely candidates for bent valves would be cylinders 1 and 4,
> right?  I did think it was nice that a past owner marked TDC with white
> paint so it was easy to find.
> 
> Not sure when I'll get to look at it, it will probably be a few days.  I
> usually work 4 long days then take Friday off though the impending crappy
> weather might change that.
> 
> Dave Cook
> 
> 
> --- On Mon, 1/31/11, LBaird119 at aol.com <LBaird119 at aol.com> wrote:
> 
> > From: LBaird119 at aol.com <LBaird119 at aol.com>
> > Subject: Re: [Vwdiesel] Banana Rabbit--Bad news...
> > To: vwdiesel at vwfans.com
> > Date: Monday, January 31, 2011, 1:11 AM
> > =A0 I'm voting for an old belt
> > stripped the cogs at the crank.=A0 :-(=A0 =
> 
> > Pull the valve cover and release the valve spring tension
> > (loosen cam =
> 
> > bearings) then try again to turn it over (first be sure
> > you've tried =
> 
> > from the crank sprocket and see if the belt moves with ANY
> > movement =
> 
> > of the crank).
> > =A0 Sounds like you might have broken the cam, bent
> > valves, the usual =
> 
> > that happens with a slipped/broken timing belt.=A0 Hope
> > not but with =
> 
> > oil in it, it's unlikely it threw a rod unless you'd
> > already heard it =
> 
> > hammering and seizing pistons don't tend to bang.=A0
> > That just leaves =
> 
> > the cam and valves.
> > =A0 =A0=A0=A0Loren
> > _______________________________________________
> > Vwdiesel mailing list
> > Vwdiesel at vwfans.com
> > http://www.audifans.com/mailman/listinfo/vwdiesel
> > =
> 
> 
> 
>       =
> 
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