I'm having the exact same issue as described here: https://www.jaguarforums.com/forum/x...roblem-137715/

I went ahead and replaced the whole tensioner with an OEM one from SNG Barratt. Installed it, torqued everything down. The squeak is gone, but the issue in the video is not. I'm using a fresh Gates (K070916) belt. It's been sitting in my garage for maybe a year or so, was a little hard to put on, but by all accounts should work. I double and triple checked to make sure the belt was a aligned.

Water pump is a year old. Harmonic balancer (crank pulley) is also about a year old. Power steering is about 2 years old. Alt pulley seems to be in excellent shape. Everything spins nicely with no wobbling.

I find it hard to believe, but could this be down to the belt again?

 

The alternator pulley 'thrust' seems to be causing the fault. The pulley looks like it is moving in and out of the alt case. (bad bearings?)

 

I think that may be an optical illlusion - I think the pulley is staying put, but the belt is what's moving (due to the tensioner going in an out). For what it's worth, the issue only occurs on cold starts and goes away after a minute or two (as in the linked post). Alternator pulley seemed rock solid and smooth as glass when rotating by hand.

That said, might be worth getting a reman Denso unit just to keep in the ol' parts hoard.

 

I don't think the alternator is the problem - as you say, that's more of an optical illusion. I'd probably replace the idler rather than the alternator - I had a problem with the idler that was a bit more extreme than in the video in that it pushed the belt off the edge of the pulleys and shredded it!

 

That's what I thought too, so I replaced the entire tensioner (and so the idler pulley is brand new too) and I'm still having the issue. Gus (JagRepair.com - Jaguar Repair Information Resource) mentioned that he had to replace the the tensioner *again* as the first new one was faulty. Just kind of bummed about this, as the part is now marked as special order from SNG Barratt, so I have no idea when a replacement will arrive.

 

OEM belt is 24mm wide and 2327mm in circumference, so the Gates one you quote should be fine. It's a tad too long, although I'm using a 7PK2345 (also Gates) without issue.

Just to be clear - have you replaced both pulleys i.e. also the one adjacent to the alternator?

 

That's very interesting about the Gates belt. I can't find the one you're using (mine says 7PK2327). Mine has measurements 24mm x 2343mm outside circumference (I assume then 2327 in the inside circumference...sorry, just realizing these things for the first time). Maybe the 7PK2345 is a euro thing?

Rockauto also lists the Dayco 5070915 as an equivalent to NCA2211AC (fwiw they say the same of the gates belt). But it's ever so slightly shorter at 2325.12 mm IC. Maybe I'll try this out.

I did not replace the pulley next to the alternator. It felt fine, but given the increased wear it's probably taken, it's probably wise to replace it. I can get a Gates replacement off of Amazon one day shipping (same with the belt). Will go one piece at a time and check back in.

Wish me luck...

 

My OEM NCA2211AC belt is also marked 7K2327, so the Gates one you have sounds perfect. Sorry, I lied, the belt I have is Contitech not Gates. I couldn't find the exact size that wasn't around the same price as OEM, hence I got the slightly longer one from the local motor factor.

Jaguar's service interval for the belt is 100K miles, but the pulleys don't seem to last anywhere near that. The idler on mine was grumbling at 30K.

Both Gates (38028) and Dayco (89016) offer a replacement for the pulleys, although they're metal and without flanges. I used Dayco for both without issue.


Good luck!

 

No worries. Besides, I'm always happy to have a spare belt around.

I ordered the Dayco belt and the Gates pulley. Should be here on Tuesday, so hopefully I'll have had time to fiddle with this stuff by the weekend. I'll probably replace the pulley first, then the belt. If that doesn't work, I'll call my mechanic and see what he has to say.

I do have some lingering suspicions about the alternator. The pulley on it seems fine, but about six months back, the high pressure power steering line near is burst open and sent fluid everywhere. I don't recall much getting on the alternator, but it's not impossible. In any case it looks kind of dirty. With the old tensioner, my belt issue would only occur on cold starts and would go away as the car warmed up. The battery is almost 4 years old and has shown some signs of needing replacement (window settings don't last like they used to). Is it possible that under cold starts, the alternator is working extra hard to recharge the battery, being extra hard to turn, thus causing the tensioner to contract during those pulsations?

I probably sound like an idiot right now. I know based on the original post I linked and Gus's writeup, I should probably just order another tensioner. It just seems so bizarre that a brand new one would be defective out of the box.

 

also, fwiw, with the new tensioner, I haven't left the car running long enough to see if the tensioner will stabilize as the car warms up. I don't want to put undue strain on the other pulleys.

 

I'd go with a new idler pulley (as opposed to the tensioner or tensioner pulley) before replacing the tensioner again, based on my experiences with same.

 

I agree!

 

by idler pulley, do you mean the one next to the alternator? (I'm going to be trying this next anyway - just want to make sure I'm not mixing up terminology)

edit: I just your post from a couple year back about the shim.

Pulley is coming tomorrow...is the bolt on this puppy also left-hand thread?

 

Not at all. I'd go as the others have suggested with the idler first. Regard it as cheap PM if the existing has seen any appreciable service. The tensioner assembly isn't the cheapest of items.

Curious - is your existing pulley the plastic type with one or two flanges? The securing bolt is normal thread, btw.

 

it's smooth. Wouldn't surprise me if it had been replaced at some point prior to my ownership. The tensioner definitely was (the old one had the updated P/N).

These pulleys are so cheap I honestly might keep a couple stocked in the toolbox in case of future need.

 

Please ignore my silly adventures with shims. Sometimes, an answer just keeps slapping me in the face and I refuse to listen. I finally spent 20 bucks on a new idler wheel/pulley and that has solved my problems. With luck, it will solve yours. By the way, I got a smooth pulley. (I don't think it's a left hand thread, but it's been several years. Best to have someone else confirm.)

 

Yep, you guys were right. Replaced the idler pulley next to the alternator, and voila the problem went away. The old one felt fine to the hand, but lesson learned: I guess sometimes you can't feel these things with hand strength.

mods, this one can be marked as resolved.

Thanks everyone. Now onto chasing down whatever's causing the hard starts and rough idle when cold...

 

Replaced the tensioner, idler and belt. the problem with the tensioner back and forth came to be.Switched things back and forth new and used and found out that I was given a belt that was packaged wrong. I went by the lengths available and got one 1 5/8 longer. Belt was going in and out on the idler pully and I added 1/8" of shims behind it now it's doing good.