Squeaky M51

Picked up a cheap 525 a couple of weeks ago that has a bit of a squeak from the belt area. Alternator looks newish and spins nicely and I have replaced water pump, tensioner pulley and the idler but this hasn't fixed it. There's also a chirp when you switch the engine off. Does this sound like the symptoms for harmonic dampener? AC belt isnt fitted right now and the tensioner is always moving a little on idle but I don't know if that is normal.

Pull the belt off and have a look at the aux pulleys, maybe a worn bearing? Check the engine pulley with a mirror and a torch for damages.

I'd say take off the AC belt and see if it improves. Not sure of the setup on the 525.

Crank vibration damper is what I would look at.

Thanks for replies guys. Will see today if I can have a look at it from underneath. Don't know how much space you have in a p38 but there's none from above without removing fan and shroud. I had a 3series with same engine a few years ago but never needed to take the spanners to it other than oil and filters

Kev12 said:

Thanks for replies guys. Will see today if I can have a look at it from underneath. Don't know how much space you have in a p38 but there's none from above without removing fan and shroud. I had a 3series with same engine a few years ago but never needed to take the spanners to it other than oil and filters

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Lots of space on the P38 but cannot see a lot without removing fan and shroud and you unlike the V8 the top of the shroud won't come off so you have to drain some coolant and remove the viscous fan.

Could it be belt wearing in? If it’s not 2pulleys, pump or tensioner/pulley the alternator is also connected by the belt and may chirp.

I had trouble narrowing it down on my P38 even with room. changed one idler to find it was the other. When I took it out it seemed fine but new sorted it.
Had a new low-noise belt too while I was there.
Be careful with the tensioner fulcrum, a little pressure and itl retract slowly, any twist and itl snap - check my thread - they cost a lot for a flimsy bit of metal. I cleaned out and refilled my tensioner too so it holds belt firm, and also had to properly grease where it goes into the FIP sprocket as It was completely stuck on from someone previously not coppaslipping cap. Could squeak if it bounces around from wear

Well the noise has gone today apart from the chirp when shutting off. Yeah fan and shroud have to come off together on this, shroud is 1 piece. I tried spraying with water last night to see if it was belt noise but it made no difference, I had gold of the damper today and couldn't get it to wiggle by hand so hopefully it's ok.
The only other thing that happened today on first start was the tensioner flicked back over its fulcrum point. The engine doesn't start particularly cleanly hot or cold, I'd guess it's a bit of chain stretch at 240k or so

Maybe there is no oil in it? You have to keep them upright or it spills out, not very noticeable when stripping a Diesel engine. If it’s not holding properly it will jump about as you rev but never seen one invert?

Water usually stops a squeak for a minute, you can also turn them in your hand and feel for rough running of the bearings if belt is off. I’d check alternator pulley spins smoothly and inspect tensioner bits. As mentioned a new belt may squeal til it runs in. You can change the lot cheap enough. only expensive part is the fulcrum arm, other bits are cheap enough on the bay

RangeRoller dt said:

Maybe there is no oil in it? You have to keep them upright or it spills out, not very noticeable when stripping a Diesel engine. If it’s not holding properly it will jump about as you rev but never seen one invert?

Water usually stops a squeak for a minute, you can also turn them in your hand and feel for rough running of the bearings if belt is off. I’d check alternator pulley spins smoothly and inspect tensioner bits. As mentioned a new belt may squeal til it runs in. You can change the lot cheap enough. only expensive part is the fulcrum arm, other bits are cheap enough on the bay

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Waterpump, tensioner pulley, idler pulley are new. Alt and PS pump feel good by hand.
However I didn't know the tensioner spring thing had oil in, I didn't remove it. Will try and get a look at it tomorrow. The spring is strong and the fulcrum is all free to move as should be.

On my P38 there are two idler pulleys?

Just the one on this, I'd guess it a different set up for AC and PAS

You’re right, I’m including the tensioner pulley late enough for me methinks

It is a v-ribbed belt BTW??

Yes

Kev12 said:

Well the noise has gone today apart from the chirp when shutting off. Yeah fan and shroud have to come off together on this, shroud is 1 piece. I tried spraying with water last night to see if it was belt noise but it made no difference, I had gold of the damper today and couldn't get it to wiggle by hand so hopefully it's ok.
The only other thing that happened today on first start was the tensioner flicked back over its fulcrum point. The engine doesn't start particularly cleanly hot or cold, I'd guess it's a bit of chain stretch at 240k or so

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Change the idlers. One locking up will do that.

https://www.landyzone.co.uk/land-rover/new-diesel-pulley-ceased-fulcrum-change.342448/
Be careful with the fulcrum arm

Quick update I think I've found the culprit

You can just make out the date on one of the pics, so it's the original one, 240k miles. If i had a bit of nylon bar to hand i'd probably turn a couple of new bushes. But I don't so new one on the way.
The wear was decreasing the effective length by over 1/8" as well as making it jump about. I did get a vid on my phone but seems it was the wrong format for the website to upload

Good effort. Thought you'd replaced the tensioner.