[Vwdiesel] Re: '96 Passat TDI engine noise nightmare!
Mike Maguire
mmaguire at dircon.co.uk
Fri May 30 05:01:33 EDT 2003
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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
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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
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