Hi. I recently purchased a 1998 X308 XJR and have some questions regarding the tensioners. I bought the car pretty much unseen and after collecting it I took it for a few local drives to see how it drove etc.

The car has recently ticked over to 102k and came with several stamps in the service book. I noticed a strange ticking noise at startup and when driving and idling a few days into my ownership. I took the car to a local Jag specialist who had a quick look around and a listen with a mechanics stethescope before diagnosing the noise as the secondary tensioners.

I took the right hand cam cover off this morning to find that I have the 3rd gen tensioners -



I have half asleep at the time and looked at the plastic on the tensioner rather than the body and mistook it for an earlier tensioner. Thankfully someone on another car forum I am on spotted my mistake and told me that I had the 3rd gen tensioners. I looked a little closer with a torch and it seems like I have the 2nd gen lower tensioners fitted too (I have highlighted what I think is the lower tensioner) -



The chains all look fine and there is no slack in them (on the right side anyway, not checked the left side yet) however I still seem to have the original primary tensioner blade instead of this later design. This seems a bit odd, if someone went to the trouble of replacing both sets of tensioners then why not change the blades?

Is it possible to replace the blades themselves without removing the primary tensioners or the chain? The upper primary tensioner guide appears to be a metal one.

Also what else is likely to be the culprit for the ticking noise? I've read that someone had a loose spark plug which was causing a similar noise so I'll be checking mine tomorrow morning when I fit the right hand side cam cover back on. Anything else to check?

Thanks

 

Replacing the primary tensioner blades is a big job as they can't just be pulled out from the top. It's hard to second-guess the previous owner's motives for not fitting new primary tensioner blades whilst appearing to have done the primary tensioners-maybe he (or she) thought that they were in good enough condition not to replace.

It's a question only a psychologist could answer

These engines don't like to run on low oil levels either, so it's best to keep the dipstick level at 'MAX'. This can help quieten down noises from the engine, as can using a thicker grade of oil like 10W/40, or the 50/60 grade trackday synthetics.

 

Welcome to the forum. A cautionary note: there have been reports of cars with only one secondary tensioner replaced.
As an add to Red October's comment, a vvt could be causing that tick.

 

The O/P has the XJR so it won't have the VVT units.

That's interesting about cars with only 1 tensioner being replaced-utter madness as if the other tensioner failed then it could still wreck that side of the engine...

If you've gone to the trouble of replacing 1 of the secondary tensioners, then you might as well finish the job & do the other side for complete peace of mind. My guess is that they've avoided taking off the cam cover by the dipstick, as it can be a pain in the *** to remove the dipstick clamp & they've just abandoned the attempt...

 

Missed that it's XJR, got to pay more attention. I doubt that many cars had only one replaced, but it certainly doesn't make sense.

 

Don't worry-I also missed the bit about the XJR as well & mentioned the VVT units-had to edit my reply, which is the one you see now

 

Thanks for the replies folks. The blade has no signs of cracks etc so looks fine, sent the pics off to a specialist who agrees. Bolted everything back together and fired her up, to me it sounds like the squeaking noise is coming from a belt and not the tensioners. Took the plugs out, well the first 3 on each bank as my tool was too big to access the 4th plug on both sides. There was some oil on a few of the plugs so having the seals changed, and a full service since the car is new to me. Then I can look into replacing the winter tyres for some summer ones and only then can I start to have some fun behind the wheel!

 

The squeaking noise will be either one or both of the belt tensioners-the grease dries out with age & the bearings run dry. The noise is usually worse on a cold engine-it often quietens down as the engine warms up, because the heat softens the remaining grease & re-distributes it around the bearing races.

It's not too hard to replace the belt tensioners, although the supercharger belt tensioner is much easier to replace if you remove the radiator electric cooling fans & bracket assembly.

 

There are also the idlers.

The simplest diagnosis is to remove belts and turn the pulleys by hand. The one that feels rough, floppy or stiff is the culprit.