4.2 Acc Drive Belt & Pulleys - Which to Buy?
 

I have noticed a squeal a couple times when I start the car cold. Its probably a belt or pulley and I am at 97K miles so I am going to just replace both pulleys and the belt. I have always carried a new belt 4060910 in the trunk so I only need to buy the pulleys. But I am confused about what to do. I read thru the relevant threads and have some questions that I hope I can get answered.

1. My 2004 4.2 has an idler pulley with lipped edges. Most of the replacements I can find (89016, 38028) do not have the lips. So which is better? I would go with the lipped version 49145 to match what I am removing unless a good case can be made to just use an 89016. The tensioner pulley is not lipped so it seems like the lips are not required.

2. I read a comment that the later model years have an "upgraded" tensioner that you can't replace just the pulley. I can't see any other evidence of this. It looks like the 89016 used on older engines would still work fine. Do I really need to replace the whole tensioner?

Any help to clarify is appreciated. Thanks.

Since you already have the new serpentine belt, I would install it first (without replacing any tensioner pulleys). That may be all you need to do, especially if your current belt is the original one from the factory. I replaced what I presume to be the factory belt on my wife's 2006 XK8 last July at 115,385 miles while I was having the factory alternator refurbished. With the radiator fan assembly already removed to allow me to remove the alternator, I had easy access to the belt. It still looked good and was not making any noise, but I think going ahead and replacing it was the right thing to do at the time. I ordered a new Gates K060910 belt from rockauto.com for about $22. It was a perfect fit and I have had no problems with it....

Well this is going to take another direction. I found that a small coolant leak is what is causing the squealing belt. I will start another thread about the leak.

I would still like to get answers to the original questions if possible. I may still replace those while I have the hood up. :D

Heritage shows two part numbers for the 4.2:

C2C22758 - which most pictures show as metal without flanges and;

C2C37064 - which has a flange back and front.

My original NLA plastic idler pulley had a flange on the front edge. I replaced with the metal 89016 and have no issues.

This post from RaceDiagnostics shows the 4.2 tensioner pulley. It's bolted to the tensioner arm so I can't see why it couldn't be replaced. If it is 76mm diameter like the 4.0 then I imagine the 89016 will fit, or you could R&R just the bearings:
https://www.jaguarforums.com/forum/x...6/#post1541864

The belt service interval is 100K:- the pulleys I replaced were grumbling at 30K. If they spin freely and smoothly then they're likely OK, but they're cheap PM.