Try listening with a piece of 1/4" tubing to localise the noise ... and ... CAREFUL of moving bits!!!
cheers

 

Thanks mate....I tried that with amateur stethoscope and I still cannot isolate the sound. Agree on the moving bits comment!

 

The only other things the belt goes around are the main crank pulley and the water pump/viscous fan..

Out of those 2 I would put more money on the water pump... try wiggling the fan without the belt on - there should be no bearing movement in any direction.. If there is, then the water pump bearings are starting to go... well worth replacing sooner rather than later if it is that..

Cheers,
Marty

 

All
Water Pump: Actually I replaced it in January as I was "sure" it was the culprit. But not so as in 2009 when I replaced it before. I have put this down to preventative maintenance.,

What is still intriguing to me is that the whine seems to develop after a few minutes of running

 

I didn't see the belt tensioner and its pulley or the idler pulley mentioned so far.

 

It is mentioned that idlers and tensioner have been replaced. How is tension on belt (ie does tensioner work properly). Any chance that tensioner/idler or other pulley is misaligned somehow. On our 92 trooper the harmonic balancer could rotate on itself and would chirp/squeal when motor revved. Took 2 years to find that problem. (it never came apart thankfully) Not sure on remaining parts

 

There are a couple of other things I just thought of...

When I was looking around at the parts to do my tensioner, pulleys, and belt - I found loads of different variences, part numbers etc for different models (with A/C without A/C etc)

I know that one of the idler pulleys on my 2001 (with A/C) is 70mm, and the other is 80mm...

These were all the parts I used on my belt/tensioner/idler pulley replacements:

Tensioner Assembly: ERR6439
Serpentine Belt: PQS101480
Drive Belt Idler RH: PQR500060
Drive Belt Idler LH: PQR101150

Maybe one of the idler pulleys is slightly the wrong size (I looked on LRcat.com and it had 2 or 3 variations on idler pulleys/belt sizes) and it's causing something to squeal?

I was doing my refresh of the above parts to try and get rid of a bit of a drive belt whine, and a lot of it has gone (the tensioner pulley bearing had a load of slop in it) but I've still got a bit of a whine - but I'm pretty sure it's from the alternator bearings... it still runs fine, so I'm not going to rip it out just yet, there are more important projects!

Hope this helps,
Marty

 

This is a TIB regarding noise from the belt system. 70mm old pulley size and 80mm new.

 

Hmm, that's very interesting!

I wonder what difference an 80mm pulley and slightly longer belt would have?
Surely the noise shouldn't be there even with a new 70mm pulley and belt though?

Kinda wish I'd left it until now to order the pulleys and belts and I would have put the different sizes in.. oh well... next time I do the belt, I'll swap to the bigger pulley too, and see what difference there is in whine.

Cheers ghur!

Marty

 

Thanks all for continued dialogue. As noted, yes I have replaced the pulleys (both) and the tensioner. While I am not an expert by any means they do seem to be mounted correctly. There was no change in sound after installation.

With regard to Idler pulley on LHS: Thanks for flagging the Technical BulletinNo: 12/04/99/NAS . Atlantic british are still selling the older parts (must ask them why) so I ended up with 70mm RHS pulley and the correct belt (PQS101480).

By the way there is also a later Recall D-216 dated 12/08/00 where they recalled the LHS old pulley made of plastic with one made of steel. New Part # is PQR101150K (K seems to be the number change).

Again what is mystery to me is why noise only occurs after warm up.

 

All
Update on this. I took it to dealer to try to locate.

They immediately said it was coming from Alternator but it was "not bad" and certainly not worth messing with the alternator. They said to monitor it and that I would know if it was getting worse. I can live with that for now.

 

Don't leave it too long.

Bearings are cheap.

 

My left Idler pulley went spectacularly on Saturday and now I need to replace the belt and the left pulley, also going to replace the right pulley while i'm at it. I've checked on one of those part number websites and I don't see anywhere that the 70mm was officially changed to an 80mm one. My parts supplier has said that they have sent me the correct pulleys and belt for my VIN but they've sent me the 70mm pulley and the longer belt. Does it matter? Surely the tensioner will take up the extra 0.5% length without any adverse effects?

Can I just install everything as it's been supplied? Then i'll take the old 80mm pulley, replace the bearing and keep it as a spare. Make sense?

 

There is no way I would install mismatched parts on any vehicle. Suppliers can have incorrect listings. Suppliers often do not know GEMS from Bosch on P38s either. Is your supplier a reputable well known company?

 

Bosch has different part numbers for the idler.

PQR101150K is the 80mm Bosch,

PQR500060 is the 70mm. Bosch.

It's possible his listing is missing an option notation or has an incorrect VIN seperation.

 

They're fairly reputable, it is a parts shop specialising in Land Rover parts (i.e. not a 7-11 parts shop). The belt they sent is part number PQS101630, the 80mm pulley is PQR101150 and the 70mm pulley is PQR500060. So the pulleys are same as what marty_nz quoted previously. Rather annoyingly the technical bulletin gives the number for the longer belt (PQS101630) but not a part number for the 80mm pulley.

 

Too lazy to read everything...

A screwdriver you can use as a stethoscope (did I spell that right?), take a big one, and put the pointy end on suspicious places, and put your ear on the grip, this will give you a very reasonable indication where too look.

Poke around well, too exclude things. Very good way to find worn bearings.