Hello Chaps....new owner

[Stickfinger]

AUX BELT flapping..

....this is what is happening.

I loosened the eccentric pulley.

I square keyed the tensioner back and pinned it.....

I checked the big tensioner bolt was tight.

I tightened the eccentric wheel till "nipped" up then rotated the wheel with the square hole till the pin in the tensioner came loose, I tightened off the wheel, I then removed the loose pin. (this proves the belt is the correct length/tension ?)

Started the car, all was well, then after about 5 mins the belt started to flap on the lower run between the Air-con pump and lower pulley. Car is still not idling correctly after warm up.



FYI, I just checked with Citroen Parts Salisbury (told a small lie to get the info) and got them to check the belt I have.....there is only ONE type listed on my VIN. 5750WS, this is a K6-1726 belt.....I have a Peugeot VKMV6PK1726 Drive Belt which is the same.

[citroenxm]

You turn the the eccentric to opposite position so it tightens up the spring loaded tensioner to get the correct tension on the belt.

[Stickfinger]

Yes I did that, I turned it so the spring released the pin locking the tensioner (yes I withdrew the pin ) so I know I turned it the correct way.

[White Exec]

Do you have the option of increasing belt tension slightly, to reduce belt flap?
Had to do this on AC'd BX here this week, after re-installing the aux belt. It doesn't, though, have a spring-loaded tensioner.

New belts do stretch and bed in a little when initially fitted and run.
Might be worth re-doing the tensioning after a bit of running.
Does the flapping stop at higher engine revs? If so, run it at this speed for a good few minutes, then re-tension.

[Stickfinger]

The flapping starts after about 5 mins at idle (the idle is still rough after warm-up)....it goes at anything just above idle. I tend to think (guess) it is caused/enhanced by the rough idle.

I cannot see what I could do to increase the tension.

[White Exec]

I don't think rough idle could cause the much higher frequency of the belt flap, because there's a huge flywheel there to stabilise idle speed, and that latter couldn't vary its speed that quickly.

Belt flap is usually on the lesser-tensioned (return) path of the belt. If it's happening on the "pull" side of the crank pulley, then that's unusual (or a very long section of belt run - the 2.5 situation) and should lessen if extra load is switched on - eg AC or alternator load.

Flail is always worst at idle, or just above it.
5 mins after start-up is typically the time that alternator back-drag lessens, after the alternator has replenished the battery after starting.

[Stickfinger]

It get a little worse than this...............hint, turn the volume down

https://www.youtube.com/watch?v=jkxOwPXs9AI

[White Exec]

That is an acceptable amount of belt vibration at idle, Alasdair.
Good many engines exhibit the same.
It could be possibly be lessened by increasing belt tension, but that would be at the expense of strain on the various bearings.
At driving speed, it will be minimal.
What happens when you turn on AC or heavy electrical load?

[Dieselman]

I'd say it is due the idle being irregular, which is hightly unusual for a diesel engine, they are normally very stable at idle.

It might be worth removing the intake and seeing if there is any puffing back from the valves, as happened previously. A leak down, or smoke test might indicate if there is a sticking valve...IF.

It may be nothing at all, but it's strange how it comes on after about 5 minutes, I suspect it is temperature related.

I don't know at which point the glow plugs switch off on an Epic system, they could stay on for a considerable time.

If when it's doing it, you switch the engine off and restart, does it continue as before, or work properly for a while.

If there is nothig obvious, leave it for now, it may be nothing more than the Epic pump regulating the timing. Don't forget the combustion process is most sensitive at idle, due to being unthrottled the mixture is very lean, probably about 100:1, or so.
Any slight variation will have a noticeable effect.
It might be worth checking the fuel lift sensor is being seen by the Ecu.

As it goes away when raising revs very slightly, it would appear to be fuel related, not mechanical.

[Dieselman]

As a "guess", it felt like it.....it is bloody tight

Just to clear it up....I used this, not the 40nm/60degrees
Citroen Private car book:
Stage 1 = 7+/-0.7 m.daN
Stage 2 = angle tighten 60 degrees.

Ah, great.

Normally to lock the crank I would remove the flywheel lower cover, jam the ring gear, with a flat screwdriver jammed sideways into the root of a tooth and wedged against the flat of the bottom of the engine block. Tap it in to secure it and it will never move.

You can buy tools for this. Some of these manufactured tools only have a single engagement pawl, so the rist of damaging a ring gear tooth must be absolutely minimal, if using a screwdriver.