Hello!!!

My 05 XJ8L has just been diagnosed with bad tensioner pulley/belt and is making loud whistling/whining noise when running.

How come I thought this only affects older X308 models? Has any one of you with 04 and later XJ's ever replaced/upgraded your tensioner? (I'm told it's called
"drive belt tensioner update kit") And where can I buy one cheap?

Dumbfounded,

Wolfy

 

Our 308's have timing chain tensioner issues, yours is your engine accessory drive belt tensioner.
Vector

 

O I C... so what happens if I keep driving it without updating the tensioner pulley/belt? the whistling noise seems more like an intermittent squeal now...should I still be worried?

Cheers,
Wolfy

 

Nothing, everything will be OK, forever.

OK, really, the tensioner will probably fail at the most inconvenient moment, leaving you stranded in the rain on a dark, cold, lonely night.


Vector

 

Front End Accessory Drives (FEAD) have been generally quite reliable since the advent of automatically tensioned poly belts. How many miles? For tensioners, the spring mechanism providing the tensioning force could theoretically fail, or the bearing in the pulley. If that doesn't squelch your squeal, keep a sharp eye on your crank pulley. They can begin to delaminate and will make noise for months before they get bad enough to shred or throw the belt....and even then can still be good enough as to be hard to spot. Here's a cut from Rock auto.....I'm not sure how much cheaper you could want them:

DAYCO Part # 89370 Belt Tensioner Assembly
Automatic Belt Tensioner

$30.79Add to Cart

You don't have near the magnitude of worry as when you thought it was the same issue as the early V8 timing chain tensioner issue....but if you do drive it to failure and then stop immediately, I can't think of any additional damage you'll incur, beyond the inconvenience, tow-bill, and possible safety considerations of where you are when it fails. Failure (means your drive belt will be non-tensioned, or more likely damaged / broken / off track) will result in loss of pwr steering assist, air-conditioning, and waterpump. So keep driving and overheat it and you could potentially do as much damage cost-wise as if it were the chain-tensioner (ie..new engine indicated)

 

Hey Wolfy,
The accessory belt tensioner began to fail @ 45,000 miles on my '06 XJ8. It had the same sounds as yours. I had the dealership replace it under warranty. Now the car is almost at 80,000miles with no problems.

John

 

Loud whistling and whining indicates, (to me at least), roller bearing failure in the tensioner, so eventually it will seize with the consequences outlined by the other posters. These things don't last forever. How many miles on the car ?

 

95k miles, how many belts do I need?
I understand I will also need (1) tensioner (2) idle-pulley.

Cheers,
Wolfy

 

Will this DAYCO belt tensioner assembly fit my 05 XJ8L?
So if I buy this product, I will not need to buy a separate tensioner, pulley and belt(s)?

 

The squeak is the belt going side to side and not under any control in that direction. The bulletin recommends replacing the drive belt and idler pulley only. It does not mention the tensioner. The idler pulley is of a different design as it has raised sides that control the side to side movement. Supercharged cars get a lot more that includes a new SC belt, SC pulley bracket, SC belt tensioner, and SC idler pulley that includes grooves to keep the belt aligned. All 4.2 engines before 2006 are relatively easy. 2006 and later are difficult because the AIR pipe runs right in front of the idler pulley and bolt. So, with all that said, I recommend getting a new belt and IDLER pulley, NOT THE TENSIONER if you go by the bulletin. Land Rover has the same problem on the same engines, by the way.