97 XK8
Ordered the new chain tensioners since the rattling on startup was a sure warning that it was urgent. Found out that the parts were being delivered today, so I hustled out to the garage and pulled the right hand cam cover. What to my surprise...nice new latest version chain tensioner! Hmmm... a good thing fer sher, but....did they change both?? Seems unlikely they wouldn't, and I hate to pull the other cover if it's not needed....but what if? Anyone heard of replacing just one?
OK, assuming that both tensioners were replaced, yippee!! Then what the hell is that rattle about?

 

Primaries will also rattle. A few years ago someone found only one secondary replaced, but it's unlikely.

 

^^+1
Member DaveInVA's car had had only one of the plastic secondaries replaced, but his was the only case I've read about.

I would pull the LHS cover to be sure. If your early car is like mine, you won't have to fight the dipstick tube retainer since it attaches lower on the motor (around the PS pump mounting, IIRC) rather than to one of the cam cover bolts.

For the sake of the cost of a gasket, you will do no harm to drop the sump and clean out what's in there, as this isn't always done during a secondaries-only repair. The primary slipper guides are also plastic, (IMO) a bit rubbish and can disintegrate and drop detritus into the sump that gets sucked into the oil pump strainer: See this post of Terry Young's:

https://www.jaguarforums.com/forum/x...1/#post2112274

Failure here isn't potentially as catastrophic, so you may wish to defer on a full rebuild until you have a better handle on where you want to be with the car (i.e. is it a keeper or a short-term toy) - your call. You may be able to snake an endoscope in there to get a view of the primaries once you have the cam cover off.

 

Take that cover off...
What is the condition of the lower slipper in the one you have off now? Please post a photo, or six.

 

there are 4 tensioners