Can you help diagnose this sound?

Hi guys, I'm calling on your help again to diagnose this strange sound coming from what sounds like the nearside front end of my 300tdi (97k miles) How I would describe it is - It sounds a bit like metal plates vibrating. You can make it out in the video when I rev the engine up and it stops when the engine is idling. It happened a few days ago as I was pulling into my driveway, up until then everything was fine.
My initial thought is the belt tensioner (britpart), even though it's done barely 100 miles since I put it in(that was quite a few months ago and only recently just started driving the land rover again) I did take the belt off and checked for play on all the pulleys but couldn't feel anything.
Thanks for any help you can give!

Simple test, run the engine with no belt fitted, obviously only a short test for example as long as your video will be fine.

Idler pulley bearings?

It does sound a bit like dry/failing bearings, if removing the aux belt doesn't cure it then it could potentially be the timing belt idler/tensioner. Do you know when it was last replaced and if so whether the bearings were done (they should be)?

Kwakerman said:

It does sound a bit like dry/failing bearings, if removing the aux belt doesn't cure it then it could potentially be the timing belt idler/tensioner. Do you know when it was last replaced and if so whether the bearings were done (they should be)?

Click to expand...

Unfortunately I don't know when it was last replaced. I will try with the belt off tomorrow, if that fails then it’s down to the garage. The one thing the video doesn’t show is how loud the noise actually is, it’s a very loud grindy noise even when going 10mph down the road. Come to a stop and let it idle and the noise stops.

Blizzard44 said:

Unfortunately I don't know when it was last replaced. I will try with the belt off tomorrow, if that fails then it’s down to the garage. The one thing the video doesn’t show is how loud the noise actually is, it’s a very loud grindy noise even when going 10mph down the road. Come to a stop and let it idle and the noise stops.

Click to expand...

If you don't know when (or even if) the timing belt has been replaced then it is definitely worth getting it replaced. Worst case it has never been replaced and is 30K over its max mileage (not to mention many years over its 5 year life)! Mid case is that someone has previously replaced the belt but left all the original idlers/tensioners fitted. Best case is that the whole lot has been replaced but unfortunately you don't know when. Replacing the complete set is the best option as it gives you a fresh start and should prevent a belt failure related breakdown with all the hassle (and expense that involves) plus you would have to replace the belt kit as part of the repairs anyway! Hopefully the belt off test will prove it one way or the other

Hi, thanks for the help guys. I have just tested with the belt off and could not hear the noise. It seems like its coming from the water pump area. (when this noise first appeared suddenly, I noticed the temperature guage was nearly towards the red, when it normally sits at half way, pointing straight up.

I'm hoping this isn't just a coincidence and its something to do with the water pump (I think it also britpart, curse them!)

Blizzard44 said:

Hi, thanks for the help guys. I have just tested with the belt off and could not hear the noise. It seems like its coming from the water pump area. (when this noise first appeared suddenly, I noticed the temperature guage was nearly towards the red, when it normally sits at half way, pointing straight up.

I'm hoping this isn't just a coincidence and its something to do with the water pump (I think it also britpart, curse them!)

Click to expand...

Some water pumps suffer from an issue where the impeller starts slipping on the shaft, if the pulley/bearing feels ok that doesn't nesessarily mean it is ok. If you had issues with the temp at the same time then whip it off for a look (might be worth getting a spare gasket and set of bolts first as they should be classed as consumables) but then again if you are doing that it may just be worth replacing with a descent make while you are at it. Other things to look at are the tensioner pulley, give it a quick spin by hand, if the bearings sound dry that could be the issue, or alternatively the alternator but that's less likely. Oh and don't forget to do the timing belt in the near future!

Funnily enough, SWMBO's (300Tdi) water pump has just failed with a rather similar noise - three years old, and made of chinesium. A new QH one (£30) off the bay of fleas and order is restored...

Kwakerman said:

might be worth getting a spare gasket and set of bolts first as they should be classed as consumables

Click to expand...

100% agreed - replace the bolts and gaskets - less than a tenner .... no might about it!

While taking bits apart to replace the water pump, P gasket and have a look at the timing belt I noticed that the alternator pulley was wobbling when I spun it. Took the pulley off to find this:


i'm guessing this is not normal, and could potentially be the source of the noise.

Most likely. I'd do it up nice and tight with loctite on the threads then check it runs true. The threads under the filings should be OK

Kev12 said:

Most likely. I'd do it up nice and tight with loctite on the threads then check it runs true. The threads under the filings should be OK

Click to expand...

Same advice, as long as the threads on the end look good once it has been cleaned up, refit the pulley, couple of washers on the outside to ensure the nut is on the threaded part of the spindle and tighten up properly with locking compound. If you cannot get the nut to tighten down because of the worn threads ten it is probably time for a replacement.

I would suggest that you put the pulley on the shaft and see it there is any up / down and side to side movement of the pulley on the shaft. If there is then there is a good chance the pulley will run slightly off centre and that will cause aux belt tension to pulse which may end up causing tensioner / belt squeak issues. You may be ok with it as a temporary fix but you may need a new alt (and pulley) in the long run