Hi Guys,

I have noticed a noise connected to engine speed that is prevelant below 40 mph. I'd love to launch a question about how to track down this noise which is starting to bug me, but it is really hard to describe. Sounds like a cross between high pressure air escaping and a bad (squeeky) bearing. Not directly related to forward velocity (noise stops or diminishes in Neutral) so it is not suspension related.

I can't help but wonder if it is the 1 month old belt so I want to trouble shoot that first.

Years ago I learned that one can sprinkle corn starch on a noisy belt - quiets down right away. I don't want to assume anything on a car that is 15 or 20 years newer and can be really $$$ expensive to fix. So let me ask an over cautious question: Can I safely corn starch the belt on a 1998 XK8 for this kind of test?

I'm open to better ideas, but if it is safe this seems like this is still the easiest test.

Thanks a bunch,

John

 

Record a little video with the audio on and post it. That would help diagnose it.

 

The belt is easy enough to remove, so take it off, and feel all the pulleys for slop, vibration, grinding and anything else you can think of. It sounds like a pain, but it is the most direct way to diagnose a noise coming from the front of the engine.....Good luck.....Mike

 

can't see why not.

belt is still rubber, pulley is still metal even if they charge for them
like they were platinum.

corn starch certainly wouldn't be any more abrasive than road dust
coming through the radiator.

 

BTW, just made a video detailing serpentine belt replacement.

 

John,

If the noise is coming from the belt then it will be related to engine speed - not road speed and won't disappear in neutral.

Jaguars do seem to be susceptible to belt noise (especially if they've had even a small amount of coolant spilled on them) which screech at startup but this often goes away after a few minutes. For belt driven items, failing water pump bearings are probably the next common culprit followed by alternator bearings.

The noise stopping or diminishing in neutral makes me think transmission related ......

Graham

 

Well Graham you sure got my attention !! All I need is a transmission issue . Well I took her for a ride today alone (no dog, no lady, no music) and really listened to this. Good news is that it is engine related velocity was just a correlation to engine speed. I bet it is the water pump bearing, but I'll have to remove the belt and check each pulley one by one.

I'll come back if I have any questions or to report on what it was if/when I find it.

Listen I wanted to thank all of you for jumping in and giving your opinion. I really appreciate it.

John

 

John,

Good news that you've definitely got it down to being related to engine velocity.

One other thing add to the checklist - the belt tensioner is a known fault.

Graham

 

I agree on the tensioners. You may find that the tensioner pulley and the idler pulley are both starting to go.

The wide grooved belts with spring loaded tensoners used on these cars are less likely to sqeal than the narrow vee belts and fixed tensioners on some other cars.

The good news is bearings are replaceable on the metal pulleys. Ours had metal pulleys on the supercharger belt and plastic pulleys on the main belt. I've replaced the plastic pulley on the main belt tensioner with a metal one and put in a new bearing (both courtesy of ebay) and will shortly be doing the same with the idler for the same belt. The bearings in the metal pulleys are new as well.

It does require a bit of elbow grease and skinned knuckles but it is very doable, particularly if you get hold of a bearing puller/gear puller.

As far as symptoms go, there was only one squealing pulley but each one I went at turned out to have play or made a grumbling sound when removed and turned by hand.

Materials and postage for 2 ebay used pulleys and 4 bearings has come to about €80, which works for me.

 

Not to hijack the thread but it seems appropriate here. See video below. It's driving me nuts! Also engine speed dependant. I've tried 3 belts to no avail so it's gotta be a pulley or tensioner...right?

<iframe width="560" height="315" src="https://www.youtube.com/embed/KfmA-zPNdX4" frameborder="0" allowfullscreen></iframe>

 

Sounds a lot like the factory water pump in my 1999 Dodge Ram did just before it sprung a leak not quite five years ago. Replaced the water pump and all was well. I would check the idler pulley first, though. It helps tremendously if you have a mechanic's stethoscope....