Hey guys, so my dad's Jag has an issue where when we cold start it, it would make a squeaky belt sound and would only go away when the engine has warmed up, and we're not sure of what's causing it to happen.
What do you guys think is the cause to the issue?
Thanks.

 

UPDATE: Sorry guys for the lack of information, I was in a bit of hurry and I forgot to put in a little bit of details.
My dad's Jag is a 2004 XJ8 Base, and we bought it from a man who garaged/not used it for pretty much of it's 16 years before us, and so I had suspicions that the original serpentine belt might not be replaced, and in that case we had bought one, just haven't got time to replace it yet... So we will have to replace it, and sorry if this bother you guys but it would be great if you guys can help us out with how to replace it? (Because there's not too much space and I can't find the post on how to replace it - Also a bit off topic but there is a first time for every thing because we never worked on a Jag before).
And while we're at it should we replace the pulley? Because I have read some posts/an online site and it appears that the design of the idler pulley is what also cause the squeak to happen.
Oh, and to show you guys the problem, here's 2 video (Which I uploaded to a place that's about cars but didn't get much help) showing the issue it has at the moment.
Thank you so much and I hope you guys have a nice day.
(And I do apologize for my bad English).

 

It could be a failing idler or tensioner bearing. At this age it would be good to check them both. The way the squeak "comes around" once per belt rev makes me thing there's either water on the belt or the belt is just old. Check for coolant leaks first, then I'd put on a fresh drive belt. Use a good quality replacement.

 

Yup, I really think the 16 year old belt may have been the cause of the issue, because as far as I can see, the radiator doesn't have a leak (Very dry)/no odd coolant smell.
Luckily I got the part, just haven't found time to replace it yet, and while at it, should I replace both pulleys? And I'm a bit curious but is it hard to replace both bearings?

 

# 2, & the bearing in # 6 will save you some money, or just replace # 6.

Water pump, thermostat, with housing, & hoses, while your already there.

 

Hey there, thanks for your answer!
For pulley number 6, is this the right part? For 2004-2009 Jaguar XJ8 Accessory Belt Idler Pulley 12493GH 2005 2006 2007 2008 | eBay
And I'm quite stupid lol, didn't realize that the pulley already came with the bearing.
Also about the other part, I would love to do all of that if possible but I would need to exchange with my dad about it.
Oh and another question, is there any well known issues with the water pump and the thermostat?

 

That one is said to fit, seems mine looked a little different

Thermostat housing is plastic, and the heat cycles, cause it to break down.

Replace it with the thermostat already installed, hear it is all but impossible to install it yourself.

And since the water pump was right there, did it also.

 

Ah, that would make sense.
Anyway I went and take a look around, but what I found are mostly plastic ones, but well I guess it doesn't brittle instantly
Also about the pulley, maybe you could provide the parts (Like part number/where to buy...) for me if you don't mind?
Thanks .

 

That pully is probably ok, i just changed the bearing in mine.

Seems that my pully had no lips on it, but my memory is not as good as it once was.

Look at yours to see for sure

 

Yea, I think mine has none too lol.
And a bit of good news is that my dad and I are thinking the same about the bearing in the pulley, so we agreed to buy 2 new pulleys for replacement (the idler and the tensioner one), and yesterday I went on the "market" (AKA eBay, Autozone, O'Reilly, Amazon), and sometimes their labelling is confused (Like the tensioner pulley is named idler pulley)...
Anyway I'm sorry if I bother you once again but can you check and see if those are the correct parts.
Tensioner pulley: ACDelco Idler Pulley 15-20679 (autozone.com)
Idler pulley: Duralast Idler Pulley 231016 (autozone.com)
Thanks .

 

If Does the new belt have ribs on both sides? Does your old belt have ribs on both sides?If the old belt and new belt are the same happy days just replace it and see how it goes. If your old belt only has ribs on one side you either need to find an old style belt but not from Jaguar because they discontinued it or replace the pulleys with the new style ribbed versions. TBH im not sure if this applies to your Jag but they did this to the XJR and it took me ages to find a belt!

 

Both of mine only have the ribs on one side

 

Hey lads, sorry for the late answer.
So to address Joe's comment: I honestly never noticed it lol but yea, here's the belt that I've bought from O'Reilly: MasterPro Serpentine Belt K060910 | O'Reilly Auto Parts
And good news: The pulleys that I've ordered will possibly arrive in Sunday, and that means we can get to work quite early and possibly fix the issue, I'll keep you guys updated...

 

Hey lads, finally got time to work on the cars, and yea, me and my dad are working on it atm



Got all the covers out, and uncovered something fishy...



Someone has done work on the engine and done it somewhat improperly...
The clamp for the hose from the air filter to the throttle body is very loose we shakes it out easily and some dust has managed to got in...
And some oil seems to appear on the valve cover which we didn’t see until we remove the top cover...
Anyway that’s kinda it for now, will keep you guys posted.

 

Manages to get the tensioner out by removing the bolt because it wouldn’t move...
Bearing seems to be good though.

 

The reason belts squeak after a start-up then die down is because starting the engine uses a lot of amps, so the alternator will be pumping those amps back into the battery to recharge it and thus put a load on the belt causing it to slip. After the engine has warmed up after several minutes or a few miles of driving, the alternator ceases to put out so many amps, and the load on the belt reduces and the squeak stops.

 

Putting her back together now...

 

Good news! It worked, and the car is silent
Thank you so much for your guys help!

 

UPDATE: Apparently the squeak decides to came back despite the fact that we replaced both pulleys and the belt... Can't think of the cause of the issue
What do you guys think?

 

Was the water pump, with the thermostat & housing replaced?