There are many timing chain tensioner threads floating around, but another one doesn't hurt. My XJR only has 120k miles on it, but it wasn't very well maintained. I have done quite a bit of maintenance work on it and just did the valve cover gaskets, upper timing chain tensioners and spark plugs. The old plugs I pulled out were AUTOLITES for crying out loud!!! Car runs much better with the new NGK Iridium's. However, I didn't come here to talk about that. I came to talk about those damned tensioners.

If you are on the original timing chain tensioners, or if you are unsure if they have been changed, I suggest you pull one of the valve covers and check. It could save your motors life. I saw various pictures of people's tensioners with the crack running down it, but what I saw in my own car made me downright sick. I had leaking valve covers and wanted to change the plugs anyways...and I had a feeling the tensioners were never touched, so I ordered those as well to do everything at once. And boy was I glad I did.

Once the valve covers were popped off, I could see the tensioners were old and had the crack running down. However, once they were out, I could see just exactly how bad the cracks were. Almost running down the entire body! To make matters worse, part of the drivers side top had broken off!! The top was also scored by the chain. It was a ticking time bomb...only a matter of time before something catastrophic happened. I wasn't able to find the piece that broke off...it could be in the oil pan somewhere, it could be crushed up into little pieces. Who knows how long it was like that.

The only thing I know is that I can breathe easier. I only did the upper tensioners. I am sure the lower ones need replaced as well, but that's for another day. Here are some pictures of the horrific tensioners.

 

Pictures speak volumes. Looks like you caught those just in time. Zip tie method?

 

Many thanks to SACHS the french engineering company that pitched these pieces of crap to the engine boys at Jaguar, 'tres bon'.....that along with high sulphur fuel and another piece of junk from ZF, these cars didn't stand a chance of longevity, thankfully all addressed now.

 

Thanks for the write-up. And there is no evidence that the level of maintenance, good or bad, has ANY effect on this defect!

 

I just did my tensioners myself, using the zip-tie method, and I have to agree, you never truly know how bad they are unless you actually pull them out to see the extent of the damage to them. On mine the nylon guides (that slide over the metal piece) were completely gone, the chain had began eating into the metal. And the tensioner body was almost completely cracked top to bottom!

This really is an easy fix, despite how "difficult" it seems. For only a couple of hours of your time (disassembly and reassembly) it could save your engine and a lot of frustration and money.

 

The method I used was the "zip tie method". There is absolutely no point to use the lock down tools and take the sprocket off and all that. Just make sure the chain is cinched TIGHT against the sprocket. Use TWO holes on the sprocket to run zip ties through...NOT just one. Make sure all the valves on the exhaust side are closed. Remove cam caps and cam. East stuff. Make sure the cam is centered before reinstalling cam caps. Before torquing them down, make sure it is able to move freely, as you dont want to snap your camshaft once you start the car.

Another little tip....dont waste the time to remove the dipstick tube. Just bend it out if the way a little bit. Absolutely no reason to remove it. I was able to bend it back to the original position after the job was finished.

On a 1 - 10 scale, I would rate this job as a 4. Its not HARD, just takes time and patience.

 

To ensure that it will rotate freely, this would be confirmed by using a 24mm socket to manually turn the crank, correct?

When I removed the cam, I had rotated it so that the flats of the cam (on the front) were on top and lined up.

 

Yes, manually turn the engine. However, I barely moved it. Just enough to see that the camshaft wasnt binding up. Then torqued down the cam caps.

Before taking the cam off, I just rotated the engine until I saw that no valves were open. Nothing moved on me or anything like that.

 

What would happen if the valves were open when removing the cam?

 

Not sure...I havent done it! I just made sure none of the lobes were pushing down on the valves and removed the cam. If your valves are open when removing the cam, they may stay like that due to the cylinder pressure. Or they may close because the lobes are no longer pressing down on them. I am not sure either way...but if your car is running right, I wouldnt be worried about it!

 

I believe all of the lobes were off of them... Will confirm when it stops raining.

 

I would take exception to the statement that there is NO reason to do the prescribed (non zip tie) method for setting the cams. In fact, the new tensioners have a small dimension difference in the tight side slipper, so the chain path is slightly different and the timing is therefore slightly different. Lay them side by side and you will see. I admit that it probably makes no discernible difference in performance, but NO is a powerful word!

The reason for making sure the valves are closed in the zip tie method is so that there will be no force on the cam lobes as you loosen and tighten the bearings. It is not immediately apparent, but the cams are hollow and are not designed to take a lot of normal bending force. Several posters reported snapping the cams when doing the zip tie method, probably because the did not loosen and tighten the bearing caps progressively, in a sequence.

 

"Its not HARD, just takes time and patience." Someone who used to write frequently on this forum said, "Patience, the most important tool in your tool box!"

You make sure the valves are closed, as Ross noted, is so you don't snap your camshaft when you torque the cap bolts. Which is why you also read every single thread on this subject to capture all the nuances.

What is interesting is that after 13 years since the last 27 engine with plastic tensioners was built, there are still units that haven't been converted.

 

Just bought a 2000 & her timing was just done in 2013, winning lol.

 

The tensioners were French? They were getting back at you for Trafalgar and Waterloo.

 

Sachs? French? Tell that to a German

Sachs is German - in and out...

I'd more so say it was Jaguar in the first place trying to be modern with plastics in the engine... First company to use a plastic intake and plastic valve covers

 

New owner of a 97 XK8 with 45673 miles on it. A beautifully maintained vehicle with clean car fax and a few minor repairs. Do I need to be concerned about the tensioners in a 97? I am not mechanically inclined and will be taking it into a shop to have a check up fairly soon.

 

Best thread/site for walking a DIY'er through the process? And a source for parts? Thanks! Anybody?

 

If the cam sprocket is in exactly the same place (not loosened), and the chain is zip-tied to exactly the same teeth on that cam sprocket, timing will remain exactly the same. A slight difference in chain path (due to the chain now being properly tensioned) should have no effect on the original position of the cam sprockets.

 

If you have no evidence of the updated parts being fitted in the car's history, make this your number one priority - it's playing with knives.


From my original post another rant, Ford ownership and their modernizing program will have influenced the plastic parts additions, ground breaking? more like cost cutting! Sachs is German so apologies, but the French arm of the company designed and offered these parts - this from a guy who worked at Jaguar and designed the engine, he's a member on here