I ran into a guy the other day in my area and we was just conversing about cars and he has a 97 XK (well he had)a XK8 he told me a nightmare story he went through with his car and it was with the chain tensioners and I never knew of this very real nightmarish issue with our cars So, I knew were to come to get the info on this very real issue and here I am.. Sometimes I do think I hear a start up rattle in the engine on a cold start up and only a cold start and for sure not on a warm start up.. Look I believe in preventive maintenance and this for sure is PRIORITY ASAP! Now I do need some info on what to change to correct this issue long term and were to obtain the correct fitment upgraded parts other than the dealership parts dept and I will let my independent mechanic do this job for me asap and hopefully wont break the bank. Any help will be a welcome.

 

The secondary tensioners on the 4.0L engines were made of plastic until late 2002. They are prone to cracking and failing. This is very bad since our V8s are interference engines. Meaning the wrong bits touch and the engine dies.

In Aug (?) of 2002 Jag switched to metal tensioners and solved the problem. A search of the forum will turn up many, many, many threads on this subject.

Remember it is the engine build date that matters, not the car's build date. You can check the engine number and it will give you its build date, but the only way to be 100% sure on an '02 is pull a valve cover and look. If you see aluminum tensioners, great. If you see red-ish plastic, have them changed.

 

Looks like you have two cars to deal with. My '02, manufactured in June of '01, came with plastic tensioners. The change to metal tensioners was August 2001.

Most of us have used the '00 - '02 Lincoln LS/Ford Thunderbird secondary tensioner parts as they are significantly less cost than the same things in Jaguar boxes.

Cam Chain Tensioners Lincoln LS Part Numbers
https://www.jaguarforums.com/forum/j...34/#post330655

On-line Ford dealer parts stores have proved to have the lowest prices.

Be sure to replace the bolts.

If you feel the need to replace the valve cover gaskets FelPro makes them for the same Lincoln/Ford engines which are, of course, the same as our 4.0L V8's.

 

Below is one of guides that have been provided by members, using the zip tie method:

https://www.jaguarforums.com/forum/x...ics-how-52653/

This particular one was on a XJ8, I believe, but is very similar to the XK8. The biggest difference is the location of the header tank. It's a good idea to replace the small hoses to the header tank, they become brittle. Also, the thermostat housing and thermostat should be replaced. The aluminum housing by Welsh Ent. includes a new themostat and appears to be a quality item.

 

The Upgraded Tensioners have a Metal Body. The Wear Shoe portions of the New Tensioners are Plastic, and, with time, will also change color to red-ish.

 

Welcome to the forum. You didn't mention how many miles you had on the car. I went through the same thing when I bought my 2000 XK8 and that is when I became a real believer in this forum. I replaced my secondary tensioners right away when the car had 40K miles on it. The primary can wait quite a while and do give some warning. The secondaries just go boom. Big expense. The following thread below gives the experience I had in replacing the secondary tensioners with pictures. Not that bad of a job if you are very careful. Have fun and read all the post you can on the subject. And if you are hearing noises stop driving the car until you address this problem. A car in my area had the boom failure and it cost him $8,500 to get it fixed.




https://www.jaguarforums.com/forum/x...ics-how-52653/

 

I just changed mine this past weekend. I only have 6k miles on a 01 and my plastic ones were alreadys starting to crack. Very wise to change them as soon as possible.

 

Paul is correct. Even the metal tensioners have plastic tops. The earlier generation plastic version look like the picture below. On 3rd gen tensioners only the top portion that meets the chain will turn red. The body of the tensioner will be silver metal.

 

I replaced the secondary tensioners on my 97 XK8 (74K miles) about 3 weeks ago. The original tensioners were in good shape although the plastic had turned a burnt orange color and there was some very, very small cracks starting in the notch area, which I believe had a long time to go before causing the plastic to break away from the metal innards of the tensioners. After I got them out of the engine I drilled a 1/4" hole in the discolored plastic and found that the discoloration was only about 2 mm deep. This further proves to me that the Nylon (I believe that's what it's made from) had a lot of life left in them. All that said, I still feel better now that my engine has the gen 3 tensioners installed.

As for the actual removal and replacement of the tensioners, I learned the hard way that the exhaust cam can be a bitch to put back in position and that's because some of the cam lobes can be pressing down against the valves and that makes it tough to get them back where they belong when retightening the cam saddles. If the engine is cranked over by hand ahead of time you can get to a situation where none of the exhaust cam lobes are in contact with the valves and that makes it a simple matter to get the cam shaft back into position after you have replaced the tensioners. Obviously this cam shaft positioning has to be done BEFORE putting on the tie wrap and loosening the saddles. It took me about 12 hours to do both sides and I believe that half of that time could have been saved with this procedure. The next Jag that I buy will be easier. BTW, it cost me $230 to replace the tensioners, gaskets and spark plugs.