When I set out to do this maintenance, I never expected to get flummoxed by something as simple as a pulley and a tensioner. There are so many other things on this car that seem like they’d be bespoke or hard to find! Pulleys and tensioners seem like something an engineer would grab out of the parts bin and slap on, no questions asked.
Boy was I wrong.
A brief catch up: I found out my supercharger belt idler pulley and tensioner both had marginal bearings, so while I had everything off and accessible, I figured I would replace them. This led me down the rabbit hole of unavailable parts and $150 pulleys.
At last writing(s) RockAuto was putting the ACDelco tensioner in and out of stock on a seemingly hourly basis and the seller for the $150 pulley had yet to actually ship it. Furthermore there were some whispers and mummers about update kits being a thing.
With concerns that I wasn’t going to be able to find a tensioner at all, and concerns the one idler pulley I’d found wasn’t going to ship, I started to explore the option of replacing bearings. Most of the information I’d found said you need to either read the numbers off the face of the bearing or measure it so you can find replacements.
The bearing face reads “HSR S 167" which is... unhelpful. After contacting some ME friends, we thought the other side of the bearing might reveal something useful. This meant removing the captive bolt, but after a little bit of swearing it was out. However.... the other side just read “HSR S 204".
So I measured. 24mm OD and 17-18mm ID, but I couldn’t get precise measurements without pressing the bearing out, not something I was willing to do until I had a replacement in hand. One marginal pulley is better than zero.
However, with the bolt removed it sort of just looked like... a pulley. And I recalled one of the major manufacturers will let you select a pulley by size. Retracing my steps I determined it was Gates, and a few clicks later I had a pulley that, at least in the dimensions provided, was identical to this one. My MEs seemed to think the load rating of the bearing was appropriate for the application too...
Better yet it was in stock nearby!
Ok... so now I have this new superpower, can it be turned on the tensioner!?
But hark! A feeler I sent out of facebook has a bite! There is an update kit and there is a site selling everything for 180 GBP.
But they don’t ship to America.
So I contacted my other trusty parts dealer and sure enough they have it all for about 240 GBP. Not exactly cheap, but still less than I was looking at paying for just the pulley and tensioner.
But what does the update kit do? Is it solving a problem or is it just a parts availability thing?
No one knows!
All of the parts from the update kit appear to be off newer XKs and the like, which I think used the same or a very similar engine (IIRC Jag got a lot of mileage off this one engine...) so maybe it is just a parts availability thing?
If that is the case I am comfortable with trying to just replace the pulley/ bearing with generic replacements.
- I have 0 tensioners on order or on the way.
- I have 1 idler pulley (returnable) ordered but not yet shipped. ($150)
- I have a lead on 2 upgrade “kits” for between $300 and $400 USD.
- I have a lead on 1 idler pulley replacement that may work for $35 (or $25 if I want to do Amazon)
Next step, I think, is to pull the supercharger tensioner and see if I can pull the same hat trick using the Gates website. If I can.... I think that is how I’ll go. If I can’t, I’ll order the whole update kit.
I’m leaving the pulley order open in off chance I need it. I have 30 days to return it and at this point I need to start getting parts in.
Oh and the rear brake pads I ordered are from a non-R (oops), so those have to go in the trash and new ones are on the way.
Bonus picture: What they couldn’t like... put a Jag sticker on it so at least I could pretend!?