Aux belt flapping and making a deep rumbling noise

[johnny625]

OK,

Here is the VIN:

VF7**************[VIN obfuscated, can be read by forum staff]

Other code I can find in the car papers which I guess is engine related:

PSADHZ10CUW3030214


I would be very thankful to know what length belt I need.

[elma]

I can't find exactly what I was looking for but it looks like your car has a 1744 belt and a Sanden int compressor as standard.

From Sevice Citroen

[johnny625]

Thank you very much. It seems as something is up with the vibrations of belt. Nevertheless I will still try it with a shorter belt.

Anyone had any experience with fitting one way clutch alternator pulley in an XUD?

I got a second opinion and they said retrofitting the alternator with a clutch pulley has a high chance of solving the belt vibrations. I am left with few other choices. If a shorter belt doesn't fix things an alternator clutch pulley it is.

I also have some suspicion of things not being right with the crankshaft. Maybe a bit to much axial (in/out) play. Today while trying to see the make of the AC compressor I levered a pry bar between the sump and the crankshaft pulley. The crankshaft moves a little axially though I understand that this is normal in older engines (not sure about the amount permitted in XUD's though). I really couldn't measure the amount of movement but it seemed barely perceptible, maybe a small fraction of a millimeter.

[Stickyfinger]

Have you checked the details on the plate of the AC compressor to check the "type" fitted ?

[RoyChristie]

Johnny, have you checked that your air-con compressor pulley spins without drag or rumble
I just sprayed mine with grease to get rid of a dreadful racket and the noise is diminished and the roller on the tensioner has stopped dancing

SO ...
my question is
...
what length belt do I need for a V6 Xantia to bypass the aircon compressor

[CitroJim]

SO ...
my question is
...
what length belt do I need for a V6 Xantia to bypass the aircon compressor

I used to know that Roy... As I've done it...

The answer will be on this forum somewhere...

[CitroJim]

1550mm seems to ring a bell, thinking about it...

The routing is every easy and very natural...

[johnny625]

I checked the AC compressor. Its definitely the Sanden unit that is in the diagram that was posted by elma.

Otherwise the AC pulley is fine, no binding, no play or anything. I tried things with a shorter aux belt today. Despite the tensioning it to the right amount and making the holes line up, the belt still jumps around. The auto tensioner even more so, up to the point of hitting the plastic protective cover of the cam belt above it.

I will try things with an alternator clutch pulley tomorrow hopefully. It that doesn't fix it I don't know what will.

[myglaren]

Is the crankshaft pulley a solid one or a dual mass one?

[lexi]

Johnny, have you checked that your air-con compressor pulley spins without drag or rumble
I just sprayed mine with grease to get rid of a dreadful racket and the noise is diminished and the roller on the tensioner has stopped dancing

SO ...
my question is
...
what length belt do I need for a V6 Xantia to bypass the aircon compressor

A tailors cloth measuring tape on the correct route around the pulleys will give you the size Roy.

[johnny625]

Is the crankshaft pulley a solid one or a dual mass one?

Its a solid one. A standard one that comes on XUD's. The pulley seems fine and I even tried it with a brand new (solid) pulley and still had belt flapping.

[myglaren]

Had it been a dual mass pulley it could have been that breaking up.

Back to the drawing board

[elma]

Seen as it was fine before something has to be different.
I'm not sure what but you must have a faulty or misadjusted component on the aux belt system.
I doubt it's to do with the belt routing as the problem began without the belt being removed.
Your friends advice that uneven compression could cause it does make sense to me but I'd have thought you would have noticed a change in the engines behaviour as you are clearly a person with a mechanical mind.
Maybe worth doing a compression test before fitting the clutch? Especially if you have access to a gauge as it would be free.

[elma]

Also it may be worth using a stethoscope to home in on the noise in case it is the ps pump, ac compressor etc.

[elma]

Reading through a few other forums people with similar problems seem to generally fix it by swapping the crankshaft pulley or the alternator.