[Vwdiesel] Re: '96 Passat TDI engine noise nightmare!

[Nate Wall]

I doubt very seriously its a loose crank sprocket
bolt. The T-belt will soon come off if it is!  The
ONLY way, and let me emphasize ONLY, because I tried
everything else first, I was able to hold my engine
from turning when removing that bolt was to remove the
oil pan and wedge a 2X4 between the crank thows and
block, and then I thought I may crack the block. It
took BOTH feet pushing on a 3 foot cheater bar to get
it loose. Were talking in excess of 250 ft-lbs torque
on that bolt. Clutch slip, pry bar pops out of the
flywheel teeth, etc. with other methods I've tried.
You could try to see if it'll tighten up w/ the
starter removed and the pry bar in thye flywheel.

Other thoughts? A wild guess is either crankshaft
endplay is too great (thrust bearing?), or a wrist pin
may be making noise. Its not a hydraulic lifter noise,
or injector noise is it?

--Nate

--Nate
--- Mike Maguire <mmaguire at dircon.co.uk> wrote:
> This is a multi-part message in MIME format.
> --
> [ Picked text/plain from multipart/alternative ]
> Hi folks .... progress report after following up on
> earlier suggestions ... and some further questions
> ...
>
> I seem to have eliminated the alternator, serpentine
> belt tensioner pulley & a/c compressor from being
> the cause ... so maybe it is a loose cranckshaft end
> bolt. I have yet to check.
>
> Found some time this evening & removed engine top
> cover and timing belt top outer cover. Ran the
> engine, stationary on tickover. Noise re-appeared
> within seconds. Tried out mechanic's stethascope but
> heard nothing significant from alternator or a/c
> compressor areas.
>
> Removed serpentine belt (this is the 3 belt version)
> from alternator & a/c compressor pulleys. Mmmmm ...
> plastic tension roller sound a little "dicky" when
> spun and oh-oh there's a little play in the a/c
> compressor bearing. However, no noises from either
> the alternator or the a/c compressor when spun by
> hand.
>
> Re-started engine & ran on tickover with serpentine
> belt (& so alternator & a/c compressor) effectively
> disconnected ... noise immediately re-appeared and
> did seem to come from lower down, i.e. the direction
> of the crankshaft pulleys. Stop engine.
>
> Ok, so noise not a/c compressor or alternator ... so
> quite possibly loose crankshaft end-bolt holding on
> sprocket to which pulley wheel is bolted.
>
> QUESTIONS
>
> A - IT'S NOT THE ALTERNATOR OR A/C COMPRESSOR ... SO
> IF IT IS A LOOSE C-SHAFT END BOLT
>
> - Can bolt be re-tightened in situ?
>
> - What are the risks, e.g. if the sprocket/c-shaft
> interface/keyway is chewed up enough not to re-align
> properly when re-tightened
>
> - Do I need to remove the pulley wheel from the
> c-shaft sprocket before re-tightening the end bolt?
>
> - Haynes manual gives a 2 stage process 1. tighten
> to 66 ft lbs. 2. tighten another 90 degrees. My
> guess is stage 2 must end up with over 100 ft lbs -
> 130 ft lbs or so ... Is the Bentley info the same?
> Reason for asking is that I don't have an angle
> guage and if it is a loose end-bolt, I only want to
> tighten it up temporarily so that I can then have
> this all checked out & aligned properly together
> with having all the belts & rollers replaced.
>
> - How best to hold the c/shaft in place ... put car
> in 1st gear etc.? ... or wedge a long screwdriver
> against the starter ring gear teeth via the rubber
> bunged hole in the top of the transmission
> bellhousing? (is this actually possible?) I'd much
> prefer not to take out the starter motor to try from
> there, partly because the ring gear looks so much
> further in the bellhouising from the flange the
> starter is bolted to that I'm not sure that I could
> get a decent purchase on the ring gear with a
> lever/large screwdriver anyway (& taking out the
> starter is a pain in the *** itself) but I've never
> tried before, does it work?
>
> -anything else to be aware of?
>
> B. IF IT TURNS OUT NOT TO BE THE C-SHAFT END BOLT
> WHAT ELSE?
>
> - Any further ideas?
>
> - By this stage I'll be back to the throwing myself
> off the bridge scenario!
>
> Pointers from anyone who'se been down this road
> would be much appreciated.
>
> Mike
> Exeter, UK
>
>
>
> *********************
> *********************
>
>   Hi,
>
>   At 104K miles, a week or so my tdi engine started
> to make the odd noise ... an occasional "chink" that
> wasn't increased in frequency with engine speed.
> Kind of sounded like something non-rotational
> catching something that was rotating. Over the next
> few days this noise came & went, but didn't sound
> too bad, and everything seemed to be working just
> fine. Saturday I went on a longish fast run and
> stopped at my daughter's on the way back for a cuppa
> (tea that is) ... and as I drove in to her place ...
> oh hell, what a horrible noise! Still sounding like
> something non-rotating etc., but now seriously noisy
> and really quite frightening. Not so much "chink" as
> "rattle/crack/rattle"!!! and loud enough to attract
> notice from folks on the pavement!
>
>   Well, I've taken off the top cover over the
> cambelt and as far as I can tell, although 44K miles
> on from the belt change, this seems fine (I can just
> turn the little pulley (?) which is bolted to the
> backplate at the top with my fingers (so not too
> tight & not too slack I guess) and the belt itself
> seems ok.) The serpentine belt & v belt also seem
> fine although the v belt could do with just a little
> tightening (no slip or screech mind you)
>
>   So what the heck can this be? It's not cyclical,
> but clearly something is catching on/crashing
> against something that is, although the frequency
> doesn't increase as the engine revs increase.
>
>   My thoughts ... it sounds perhaps like:
>
>   - a pully wheel driven by one of the belts that's
> loose in it's keyway and is driving some sort of
> freewheeling device - maybe the water pump impeller?
>
>   - a starter dog that's catching on the starter
> ring gear teeth?
>
>   - something very very nasty in the fuel pump?
>
>   - something that's come loose in the engine itself
> which is catching on something rotating ... but
> intermittently?
>
>   - something very very nasty in the aircon
> compressor? (my aircon went o/s recently ... loss of
> refrigerant & then again after replacement by the
> dealer ... and subsequently, when I depressed the
> aircon switch, the usual distinctive metallic
> "click" that indicates the pump has cut in also
> disappeared ... could this be the signs of an aircon
> pump beginning to take itself apart internally?
>
>   Whatever it is folks, this is a very nasty, loud &
> distinctive set of noises and I am terrified of the
> likely costs in getting anyone to munch their way
> through replacing this and that component and
> destroying my wallet in the process. Anyone else
> experienced anything like this?  Any suggestions
> apart from jumping off the nearest high bridge?
>
>   Mike
>   Exeter, UK
>
>   '96 Passat TDI Estate
> ****************************
> ****************************
>
>
> --
>
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