I changed the serpantine belt about a month ago as it was squeaking on startup for about a minute and then it went quiet and everything seemed fine.After fitting the new belt I have only used the car for a short run because of the weather .I have just started the car again and there was the squealing again and a few clunking noises which was the tensioner going to the end of its travel and clunking on its stop.
Its evident that the crankshaft is throwing slack towards the tensioner on startup,and then settling down. When I removed the belt I tried every pulley in turn to see if one was transmitting the squeak but all pulleys were free.It points I think to the Alternator as the other components just pick up on touching points.The alternator and water pump were renewed about 12 months ago. Any suggestions?

 

It sounds to me more like the belt tensioner assembly is not maintaining proper tension. That would cause it to squeal on start up. The tensioner should never go to the limit of its travel if the correct length belt is installed. There is an indicator scale on the tensioner to show belt stretch/position. You should check and make sure you are in the correct range. If you don't have the shop manual, let me know and I can pull up the excerpt for the tensioner.

 

There are TSBs for many issues BUT!!!!!! They are VIN or MODEL related!!

(I hate mystery cars)

 

• Double check you got the right belt
• Check/replace both the idler and tensioner
• Squealing is typically contamination. Is your water pump leaking?

Best of luck, keep us posted.

 

I took the belt off again this morning to see if any of the pulleys were seized or had any roughness,i found nothing at all . The tensioner has plenty of spring and when I re fitted the belt the tension indicator was on its upper first notch indicating the belt is new. the belt I fitted is a Gates 7PK7328 which I am assured is the correct belt but not a Jaguar part.
On startup a slight whistling for about 20 seconds and then completely quiet running its most unusual. I did notice the tension pulley has a slight polish which indicates it has slipped on that pulley.

 

Have someone start the car or ( if you really get a full minute - several seconds), start it yourself. Have bonnet fully open in the service position - struts removed bolts in holes of bonnet hinges... Start the car and run over and observe, or stand there head under bonnet nose, over rad, have a light, look, listen... Cold pullys can behave a bit differently, at cold. Try to identify the noise maker. Replace.

I think I would be looking at replacement of the tensioner... Sounds (no pun) that way...

 

Do you mean replace all the tensioner or just the pulley part of it?

 

Do the test and see what see, hear what ya hear...? I pinch every penny but it is an important part. Acceleration part - everytime ya really hit the gas it's in action, for sure... I would say the whole doggone thing - if that's what proves has gone wrong. That's just me.

EDIT - IF it is the tensioner,,, be very careful bolting the new unit BACK in as not to strip the aluminum tread to the block or it receiver...

 

I had a similar issue during the summer. I would get a little squeal on start up. I replaced the tensioner pulley and it disappeared.

 

My original Jaguar serpentine (now hanging on a wall) proclaims 7K2327 along with NCA2211AC so you will be fine with the extra 1mm.

Is there any evidence of chafing along an edge of the belt that might indicate misalignment somewhere? Does the belt 'wander'?

The idler & tensioner pulleys are so cheap & easy to replace that I'd change them just to get them out of the equasion. Their lifespan appears to be much shorter than the belt itself anyway; I had one grumbling at around 30K miles. Dayco 89016 works fine for both: there is a Gates equivalent and I believe that you can still get the plastic, lipped one for the idler.

If you do elect to replace them, note that the tensioner pulley bolt is a left-hand thread.

 

Well today I changed both the idler pulleyC2C22758 and the Tensioner and pulley NCA7739AE both Jaguar original parts and the squeal has gone,the items taken off were I would think are servicable but definately create the squeal thank you for all your replys.

 

Good Job, Brotha! Good job. I know its a relief!