Started to notice what sounds like a bearing noise in the engine. Car has just over 110k miles and had the secondary timing chain tensioners replaced when I first got the car around 70k. It's had nothing but regular Mobil 1 oil changes since then and an oil analysis done at each change - no indications of serious heavy metals or plastics showing up in the oil.

The water pump was replaced, so I doubt it is a water pump bearing making the noise. I'm thinking (hoping) it may be some other bearing that isn't terribly expensive but it definitely comes from the front of the engine and is audible from outside with the hood down. If I roll the windows down I can hear it while driving down the road. The car has suffered no performance matters whatsoever, it's just too noisy for my liking under the hood.

This noise started some time in the past 5k miles. I'm at a loss - see attached link to video. A penny for your thoughts.


http://db.tt/Lm0wFua7

 

Pop off the belt and check all the rotating accessories for free rotation and excessive play.

The idler pulley on the engine block and the belt tensioner are common culprits. Gates 38028 is a perfect replacement for these at a bargain price: Gates 38028 Belt Tensioner Pulley : Amazon.com : Automotive (Amazon has the wrong picture, and also does not list it as a compatible part, but this really is the right part).

 

So you are suggesting it is the bearing in this pulley that's on the fritz? That makes sense since it sounds almost exactly the same as a similar pulley that went bad on a different car of mine.

How difficult was the swap? The belt tensioner pulley is spring loaded, no?

 

If it is a knocking noise check video #2 on this link and see if it might be the same noise.

Link JagRepair.com - Jaguar Repair Information Resource

 

Could be, and these are a good idea to replace around 100K miles, but also could be alternator, power steering, AC or water pump. Swap is a simple single bolt once belt is off.

 

I wonder if you could run the engine or a short period of time with the accessory belt removed to be sure it is an external source causing the noise before ordering part you may not need? You wouldn't have power steering, water pump or alternator but as long as you didn't run it too long I doubt you would create a "Hot Spot" in the engine.

Good Luck.

Barry

 

I had a rattling / knocking sound coming from the front of my XK8 the week after I changed the secondary tensioners. I was very worried but after using a small hose to my ear, and carefully using it to listen around the engine found that the noise was coming from the steering pump. It ended up being the three pully bolts - they were not very tight and the pully was moving slightly on the shaft, a quick nip-up with a spanner and all OK.

Removing the serpentine belt would give you a big clue for starters as it would eliminate a lot of items as other have suggested.

 

Thanks to WhiteXKR. I just swapped out the suspect idler pulley with the one suggested in his post. The noise disappeared. It's also a big help to disconnect the gas struts before doing anything with the serpentine belt, as others suggested.

I gambled on the idler pulley being bad and not the tensioner pulley. The risk being that I don't think it's very easy to separate the tensioner pulley from the assembly, meaning if that went bad I'd have to fork over about $120 for a complete new tensioner with the pulley attached. Odd thing is, the driver side was where most of the noise was coming from, but the idler is located on the passenger side of the car. When I removed the belt and twisted both the idler and tensioner pulleys it was immediately clear which one was bad. The idler pulley bearing was on its last legs and was starting to stick every now and again, as evidenced by the scoring on the bearing race. This could have been very ugly after another few days or weeks of daily driving. Tragedy avoided!

 

Nice work, and under 20 bucks!

 

Steve,
I'm a bit concerned - I followed your link to Amazon which told me the item doesn't fit my car, which I expected, but also that most people who bought this also bought
A+ 1 oz (28g) Organic Syrian Rue Peganum Harmala.
Have you succeeded in liberating the divine within while changing this pulley?

 

A significant Jag repair for 17 bucks...you bet!

Check out the reviews...4 1/2 stars...It looks like damn good stuff!!

 

Steve, would you know if the Gates 38028 pulley would fit my UK 2001 XKR?

Also, do you know if it is possible to just change the bearing in the tensioner assembly?

Thanks

Andy.

 

Yes, the 38028 should fit both the fixed idler pulley and the tensioner pulley.

Alternatively, I have also used this bearing which can be pressed in the old pulley: NTN Radial Ball Bearing - Radial Ball Bearings - 6L052|6303LLBC3/5C - Grainger Industrial Supply