My 97 XJR has developed a whine at the front of the engine that varies with engine RPM. It sounds like the whine the power steering pump makes when it is low on fluid, or like a set of straight cut gears whining.

This is a new development that just showed up this week, and the whine is easily heard inside the car, and certainly outside the car.

I tried to figure out where the whine is coming from by using my mechanic's stethoscope, but I only had the opportunity to probe around the top of the engine while running, and didn't want to get the probe down around spinning pulleys and belts.

Via this probing I did eliminate the supercharger, steering pump, head, but the sound was quite loud when I placed the probe on the thermostat housing.

I've got a recording of the sound here:

https://www.dropbox.com/s/63hzwp01do...ne-01.MOV?dl=0


Any thoughts? I read some of the water pump threads and it seems like this could be a candidate?

https://www.jaguarforums.com/forum/x...way-out-87816/


Thoughts? If not the water pump, what else would make this unique whine?

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Over the years I had to replace the idler pulleys for noise....but it was more growl than whine.

Take the belt off and spin everything by hand. You might pick up a clue

Cheers
DD

 

Hi Al,
Sounds very familiar indeed! Whilst it is always risky to make a diagnosis remotely, in this case I would be very very confident that the noise is your water pump.
In my case, the noise arose while driving back from London. Couldn't be heard in the car at motorway speeds, but noticed it as I pulled in to refuel. Naturally, it was pitch dark, but I couldn't see any leaks or anything obviously amiss, so elected to drive the remaining 250 or so miles home, which passed without incident. On closer examination the morning after, I could see a small amount of coolant had seeped out from behind the water pump pulley, which clinched the diagnosis for me.
Apparently you can buy a replacement water pump bearing, but to avoid the hassle of pulling the old bearing and pressing the new one on, I bought the replacement pump. Straightforward to fit, if a little fiddly due to restricted space at the front of the engine. Problem solved!

 

Thanks all. I also plan to take a little more time tonight with the stethoscope and see if I can touch the water pump housing for a more definitive diagnosis.

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Well, after some probing with the stethoscope it looks like the whine is from the supercharger tensioner pulley.

The OE plastic idler and tensioner pulleys aren't too expensive, but I wonder if there are any x-reference steel pulleys?

Much like the Gates steel 38006 is a alternative to the plastic OE NBC5012AA pulley for the A/C compressor belt tensioner it would be nice to find some less expensive and more durable steel alternatives if possible for both supercharger idler/tensioner pulleys.

Although I have JTIS, I wasn't able to pull the torque specs for the three idler/tensioner pulley bolts, although another thread said the bolt torque is 22-28Nm for the A/C pulley bolt. Can anyone confirm if the bolt mounting the supercharger idler and tensioner pulleys are the same torque value?

Also, can someone provide the belt tension for all three belts, A/C, supercharger and alternator? Again, no luck with JTIS on my part.

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Well, I found it.

I went ahead and replaced both the smooth idler and ribbed tensioner for the SC belt, and the belt itself.

Upon removing the old pulleys and belt, I noticed two things.

First, one of the belt ribs was worn completely off. Then looking at the ribbed tensioner pulley, I saw it had a small pebble wedged in one of the grooves. The little triangular piece of quartz was just the right size to fit right in the groove and 'permanently' jam itself in.

That little stone was causing the "whine"/"whizzing" and it of course ground one of the ribs of the belt right off.

Funny that a little stone could do that.

Also funny that chance had that little stone jump up into the groove and between the pulley and belt at just the right moment to smash it in.

All better now

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