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

[Mike Maguire]

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 cranckshaf=
t 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 wit=
hin 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. H=
owever, no noises from either the alternator or the a/c compressor when spu=
n 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 c=
rankshaft 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-SHA=
FT END BOLT

- Can bolt be re-tightened in situ?

- What are the risks, e.g. if the sprocket/c-shaft interface/keyway is chew=
ed 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 th=
at I don't have an angle guage and if it is a loose end-bolt, I only want t=
o 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.? ... o=
r wedge a long screwdriver against the starter ring gear teeth via the rubb=
er bunged hole in the top of the transmission bellhousing? (is this actuall=
y 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 bellhouisi=
ng 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 anywa=
y (& taking out the starter is a pain in the *** itself) but I've never tri=
ed before, does it work?

-anything else to be aware of?

B=2E 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 .=
.=2E an occasional "chink" that wasn't increased in frequency with engine s=
peed. Kind of sounded like something non-rotational catching something that=
 was rotating. Over the next few days this noise came & went, but didn't so=
und 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 c=
uppa (tea that is) ... and as I drove in to her place ... oh hell, what a h=
orrible noise! Still sounding like something non-rotating etc., but now ser=
iously noisy and really quite frightening. Not so much "chink" as "rattle/c=
rack/rattle"!!! and loud enough to attract notice from folks on the pavemen=
t!

  Well, I've taken off the top cover over the cambelt and as far as I can t=
ell, although 44K miles on from the belt change, this seems fine (I can jus=
t turn the little pulley (?) which is bolted to the backplate at the top wi=
th my fingers (so not too tight & not too slack I guess) and the belt itsel=
f seems ok.) The serpentine belt & v belt also seem fine although the v bel=
t 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 doe=
sn'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 an=
d is driving some sort of freewheeling device - maybe the water pump impell=
er?

  - 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 s=
omething 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 dea=
ler ... and subsequently, when I depressed the aircon switch, the usual dis=
tinctive metallic "click" that indicates the pump has cut in also disappear=
ed ... could this be the signs of an aircon pump beginning to take itself a=
part internally?

  Whatever it is folks, this is a very nasty, loud & distinctive set of noi=
ses 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 a=
part from jumping off the nearest high bridge?

  Mike
  Exeter, UK

  '96 Passat TDI Estate
****************************
****************************


--