Hi, hoping someone out there can cast a little light on this...

98S 300tdi Discovery, had some starting problems but these were down to runback - fixed with a new fuel hose.

That was a few weeks ago - now a new problem.

Barely noticeable at idle but very noticeable under power, a whirring, whining rattle. At first I thought it was gearbox related (auto) but having listened under the bonnet with it in neutral the whirring is there whenever the throttle is dabbed. During the brief listen I had, I could not tell if the noise was from "up front" or from deep within the engine

When driving, the noise is worse under low load, i.e. is low gears and at low speeds. It has disappeared completely several times when driving on the motorway, unfortunately, it's getting worse at low speeds and pretty rapidly, too.

First noticed the noise about 100 miles / 1 week ago.

I have not really done any more than a cursory listen at present, was just hoping some of the Discovery veterans on here would be able to suggest a few common faults that I can eliminate.

The altenator belt adjusters on the 300tdi's at work make constant whirring noises when they begin to fail, have been known to vibrate as well but not as common as the noise.
A few have let go big time trying to destroy all they can.
Just back of the adjuster which is on spring tension and chech for free play. An easy 10 min job.

Lee

An update of sorts...

I took the car to my local friendly diesel repair garage, where the main man listened for a bout 5 seconds and said :

"its probably the alternator idler wheel, I've seen the bottom pulley come loose on one of there, but that sounds like the idler"

I left it with him to take the belt off and wiggle the pulley in a diagnostic fashion.

Truly testament to the power of groups like this however that the same probable cause is identified here as from the experienced mechanic who listened to it .

Will post another report as the details unfold... and to think, I heard a whirry rattle and feared for my ends......

The pulley is available for under a fiver, just a bugger to change. Better than the £70 plus for the whole lump..

Lee

Fixed.

The idler was favourite but once the belts were off it was the water pump that revealed itself as the culprit...

What was a real surprise was that although the bearing was truly sha*ged, the pump had not leaked even a drop !!

The damage - £130 fitted. Painful, but not ridiculous by my reckoning, especially as it was taken in with no notice.