XM Accumulator Sphere

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white exec
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Re: XM Accumulator Sphere

Post by white exec »

Put the suspension of Lowest when undoing the pressure relief bolt, so the car cannot drop. :!:
You can run the front wheels up on ramps, to give better access, if needed.
OK to have it undone with engine running, so fluid returns to reservoir.

Car support
Best done not using the so-called jacking points, as they are easily damaged or bent. Get frail with age, so better not to use.
Front: Use the flat (rear) part of the front subframe, at each side. OK for trolley jack or axle stands.
Rear: If you want the wheels to hang (eg for bleeding), jack up under the heavy steel cross-tube (ahead of the spare wheel). Good place for axle stands, too. If you just want to lift a wheel, OK to jack under the small flat steel 'box' which surrounds the rear suspension rams. Use a wood block to cushion.

No need to load the car for bleeding. By putting it on Highest, the suspension is "fully pumped", which is the same as having it heavily loaded. (This is important for the rear brakes, because they are fed from the rear suspension, and brake pressure there is (nicely) proportional how much the suspension is loaded. Clever, in'it?!)
wesacosa
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Re: XM Accumulator Sphere

Post by wesacosa »

thanks Chris. I will try bleeding regulator and brakes tomorrow and report back
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Re: XM Accumulator Sphere

Post by wesacosa »

I didn't get chance to bleed the brakes but I did try running the engine at idle with the regulator bleed valve open for about 3 minutes. A fair bit of hissing and the LHM in the tank was quite frothy so must have been some air. However it's not really changed the noise


However I did notice that if you raise the idle speed even a tiny bit it seems quieter (video below there is no level change, its still on low but very slight throttle)
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Re: XM Accumulator Sphere

Post by white exec »

Hi Wes,

Apart from the normal diesel clatter, there seem to be two regular noises there
- a highish pitch tinkle, regular rhythm, loudest when you are near the alternator/pump
- a lower klonking, more noticeable towards the regulator

Wonder whether the first could be at crankshaft (or pump) speed, or even a noisy Aux belt (or maybe tensioner?) ?

Can you use a listening stick (length of bamboo cane, or long screwdriver), touched on various components, other end to your ear, to pinpoint the noises? Be careful with rotating/moving parts.

You can also try with a length of garden hose, in the same way. Makes listening very directional.

The contents of the reservoir should not be foaming/frothing, whether the depressurising bolt is undone or not. Suggests are is being circulated by the pump.
Check the suction hose joints, including the plastic elbow on top of the tank. This has very occasionally been known to split, and allow air ingress.
You can also, temporarily, run a length of transparent hose from reservoir elbow to pump, airtight connection at both ends, so that the fluid being drawn up by the pump can be inspected. It should not contain air.

Let us know what you find.
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Re: XM Accumulator Sphere

Post by wesacosa »

thanks Chris. I am less worried about the high pitched chirp, it did that when I bought it and the aux belt is pretty shredded.. Its coming off when I do the cambelt along with the mechanical tensioner. Its the knocking noise which concerns me as I don't think it did it before I did the LHM tank removal and filter clean/fluid replacement
Interesting on the frothy fluid. the second time I checked (after the valve was closed) the fluid was normal.
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Re: XM Accumulator Sphere

Post by white exec »

The filters are also there to break up any bubbles that get returned to the tank, to stop them being recirculated.
The large filter has the returning fluid fed inside it, and the small conical filter surrounds the pick-up (suction) pipe feeding the pump. Just possible that one of the filters might not be seated properly...

The only bubbles you should see in the tank, and getting fed to the pump, should be microscopically small ones, which can evade the fine mesh filters. You can dip a sample of the reservoir fluid with a small, clear container to check for bubbles there. You should not see any sizeable ones, and certainly no foaming.
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Re: XM Accumulator Sphere

Post by wesacosa »

The large D shape filter is missing its clip. It wasn't there when I took the filters out and Citroen don't sell them anymore. I tried making something up with a wire or paperclip but it just kept falling off. that said when I looked through the filler cap it did still seem to be in place
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Re: XM Accumulator Sphere

Post by wesacosa »

I decided to try and sort out the auxiliary belt noise to see if I can find the source of the other noise when the chirping is gone. I have the aux belt off, it was shredded so didn't have much time left. The alternator is noisy when spun backwards but not in the correct direction so not sure if that is the cause of the noise. however I did find a bit of movement (end float) in the LHM pump shaft when I pull on the pulley, you can move shaft in and out a few mm axially (but not in any other direction). Is this normal or is my pump knackered?
thanks
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Re: XM Accumulator Sphere

Post by white exec »

I've tried to find a figure somewhere for the max permissable end-float on the 6+2 hydraulic pump shaft/pulley, but can't find that anywhere.
Paul (citroenxm) here might be able to tell you . . . Send him a PM, Wes.

I'm guessing there should be next to none, and certainly not a few mm.
Can you see the pulley move in and out as the engine runs, or change position as the pump starts doing some work (you'll hear the regulator start to click repeatedly as it does)?
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Re: XM Accumulator Sphere

Post by wesacosa »

thanks Chris. I will take another look and see how much movement there is. I didn't check with the engine running and now the belts and tensioners are all off for the cambelt change so I will have to have a look when its back together. Doesn't sound good though does it :(
Wondering if I am ever going to have my first drive in this car !!
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Re: XM Accumulator Sphere

Post by white exec »

I put the problem on club-xm.co.uk. **
Will Brackenbury (Dieselman, there), having read your thread here, has posted this:

"No idea on the end float spec, but normally a pump with significant play, leaks.
End float should be minimal given the pump acts on axially mounted pistons.
Is the pulley tight.

I couldn't make out a particular knock, but the alternator bearings do sound noisy, which can make very bad knocking noises (like big ends gone), as the sound is transferred through the engine block.

Pumps do chatter due to the metal one way valves sealing suddenly as the piston reverses direction.

As you have suggested, use of an engine stethoscope would pinpoint the noise.

Is this a late model Xm?
Should it have a harmonic damper type crank pulley, if so, is it still bonded? Check the alignment.
Do late alternators use a sprag clutch pulley, if so it should grip on drive but freewheel on over-run. If the clutch seizes, the belt will shred.

Normally belt shredding is alignment related. Was it fitted in the crank pulley in the correct grooves? "

** Mod.note:
There are currently I.T. issues on the XM club site, which mean approval of registrations of new members can take quite some time. You won't be able to read posts there without being a member and signing in, I'm afraid. Hopefully the problem will get sorted.
wesacosa
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Re: XM Accumulator Sphere

Post by wesacosa »

Thanks Chris. Appreciate that. I have the alternator off and the bearings are noisy. Just need to go through the minefield of figuring out what the correct replacement is. The alternator doesn't appear to have a one way cluch pulley from what I can see, but its not the original alternator. Is it possible to check the part numbers to see what it should be?

As for the belt, Its more worn through than shredded. perhaps someone tensioned it too much. it does have a one piece crank pulley damper not the one with the four bolts. It looks in reasonable shape from what I can see
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