I get a faint warble, almost sounds like ball bearings whirling around. Car's running superb, I just noticed this & want to remedy it. Attached is link to video, it was kind of ambient noisy outside, but hopefully someone gets the gist.

https://drive.google.com/file/d/1UP6...AKST7iEN9/view

 

It might be the tensioner pulley. Remove the serpentine belt and see if the sound disappears. If it disappears spin the pulley with the engine off.
I wouldn't drive the car until you figure out what it is. If it is the pulley it could fail completely you will loose the serpentine belt and you will quickly overheat.

 

I'm having my heater & bleeder hoses replaced soon, so I'll just get the pulleys & belt done while he's in the area. Doesn't seem to be a persistent noise, mostly on initial starts.

Since I've solved all my suspension noises, all the once hidden sounds are now audible lol.

Edit :

I have a nice Christmas Canadian whiskey on hand, so I will likely be out tinkering & trying to isolate the sound more concisely lol.

 

When the one on my 98xj8 went bad it acted the same way. It would be loud at start up and go away after it ran for a minute or two.

 

I had the same problem on my XK8 and both the idler pulley and the tensioner pulley were bad. Rattle at start up and warble when warm. When I went to get the pullies I was informed that the tensioner assembly had to be replaced as a unit. Some engineer at Jaguar redesigned the mounting and on the updated one you can't remove the pulley. They told me they don't sell a tensioner pulley anymore.
What they don't know or won't tell you is the idler pulley and tensioner pulley are the same and on your car the tensioner pulley is bolted on with a left hand thread capscrew. I bought 2 idler pullies and changed out the tensioner and idler.
They are cheap as chips while you are already in there.

 

You should be able to locate the cause of the noise by sticking your head in the engine bay.
The pulleys are outside of the engine, so by just moving around your ear, you should be able to pinpoint the location.

An other option (if it is indeed a serpentine pulley) is to press out the old bearing, and buy new ones, they are plain cheap.
That is, if your car is already fitted with the steel pulleys, if they are the plastic ones, I should replace them altogether.

I just removed some steel ones of a scrape car, and am waiting for the bearings to arrive.
Hammered out the old ones, and I am sure that heating the pulley, and freezing the bearing, will make it it a home-job.

 

Armed w/ my LED headlamp,stethoscope & a nice glass of whiskey, I will be out tinkering, let's hope I don't spook Santa lol.

 

You can put a white paint dot on the harmonic balancer and other crankshaft pulleys as reference to see if it slips

 

I have one Christmas bicycle to assemble then I shall go a tinkering on the Jag, both these tasks go better w/ a flask !

 

Based on the number of superseding part #s for the idler pulley looks like trouble :

You can spray some penetrating oil in the pulley bearing area ( if it gets past the seals ) and see if the noise disappears . Won't last long but gives you information .

https://www.jaguarclassicparts.com/u...2-4-0-litre-v8

 

Great info. ! I just sourced 2 for $80 on E-Bay.

Thanks

Edit :

Either way it's just something I should do as preventive maintenance.

 

But do some checking with a stethoscope before you burn money and bust some knuckles (those tensioners are tightly bolted). A couple of years ago, a member did new belts, tensioners, water pump, only to discover his power steering pump was loose . . .

 

+1 on substituting both pulleys with the same replacement. Go for the metal ones, they're more durable than plastic, and you can press in new bearings if they wear out, instead of replacing the whole thing. I found that the URO one listed on rockauto was the best made and had a nicer bearing, compared to the cheaper Gates ones

 

Update :

I sprayed the pulleys down well w/ penetrating/lubricating oil, the noise went away briefly & returned upon next start. The noise is coming more so on the passenger side than driver's.

Going to do both pulleys & belt.

 

Did mine a 2 yrs back, ...this is what I used to replace mine, they easily tap out and in, minimal cost compared to buying the whole pulley...

 

Hmm I see those on EB for $3.99 a piece, that's a steal lol.

 

Now let me get this correct, the plastic pulleys cannot have the bearing replaced ?! But the metal ones can, thanks.

 

Si...

 

Sweet, found some Dayco steel pulleys for $18 a piece on EB.

 

The Daycos are a bit more tricky to replace bearings on since there's no lip or stop for the bearings to be pressed against, just takes a bit of finesse. But at their price it doesn't really make a difference, they should last long enough where if the bearings go bad you can just buy new ones.