Hey all,
I have a 97 XK8, with 62K miles, that has eaten its tensioners. The bad thing is, when I bought the car, and one of the reasons I bought the car, I was told the tensioners had been changed out at 50K miles, along with other preventative maintenance. Well, after inspecting the current situation, it looks like the upper tensioners were changed, but not to the metal ones. The issue has happened on the passenger side. So, that said, do the heads need to come off? I am worried that getting out of time that the valves may have hit the pistons. Is this something that happens? Is it worth fixing? I assume it is expensive to fix? I love the car, but I am torn on what to do since it only has 62K miles on it. Any and all opinions will be greatly appreciated. Thanks.

 

To replace the primary and secondary timing chains, guides and tensioners does not require removal of the cylinder heads. If the secondary timing chain has jumped due to a broken tensioner, it can jump up to three teeth without causing interference between the valves and pistons.

Here is a link to the Engine Repair Course that outlines the procedures and special tools needed to perform the work:

https://www.dropbox.com/s/vqpy3bbjzd...=qpw3yina&dl=0

If you cannot do the work yourself, have a local Jaguar specialist provide a pricing estimate. Depending on your location, the job could be anywhere from 2,500$US to 4,000$US.

 

NBCat, I hope you right. My concern is that the engine was jumping and making a terrible noise. I am assuming that at TDC, if the timing was off so much that valves are hitting the pistons, then the two cams flat spots would not line up. Is this correct? I have a great mechanic that can do the job, but if the heads have to come off and be reworked, I am not sure it will be worth it or not. I would also, probably do this myself, if it is more than just new tensioners and chains.

 

The only way to know for sure is to remove the cam covers and inspect the positions of the exhaust cams. The correct timing is 45 degrees ATDC.

Use a 24mm socket to rotate the engine in a clock direction only when viewed from the front to determine if the cam flats are in alignment. Report back what you find.

 

Thanks. I will go get a 24mm socket and check that out. I will let you know. I assume the 45 degrees ATDC is visible on the timing cover?

 

Rotate the engine until the cam lobes on Bank 1, cylinder 1 are facing away from each other and the flat on the cams are in alignment. If they're not, the exhaust cam is out of time.. There are no timing marks on the timing cover behind the crankshaft pulley.

 

Before taking off the heads, remove the spark plugs and use a borescope to look down and check the top of the pistons. Any impact is usually obvious.

Richard

 

Heads do not need to come off for timing chains, guides, and tensioners replacing. I just did it to my 97 xk8, however, there are special tools needed that hold the cams in exactly the right place, as well as removing the crank position sensor and putting proper holding tool there as well. Search for member “hellcat” he was local to me and loaned me the tools needed but at the very minimum he can explain further or tell you what you need.

 

Remove the camcover and rotate the engine check if it did jump or not

 

+1 this - a borescope is like $20 on amazon, have a peek inside before proceeding to next steps like pulling valve covers etc. You can check if its worth saving before proceeding to hit it with your wallet (or a lot of your time and effort).