Timing Chain Tensioner
 

'83 XJ6 upper left timing chain has a lot of slack in it, causing it to slap back and forth making a loud diesel noise. I took the cam cover off, started it up and actually witnessed this event.

How do I adjust the tensioner, and where is it located?

The upper timing chain tensioner has a manual adjuster, behind the breather cover and screen. There is a factory tool for this purpose, I made mine from a diagram in the old E Type manual. I don't know how to adjust the chain otherwise, you have to loosen the locknut, depress the spring-loaded locking pin, and rotate the adjuster counter-clockwise to tension the chain. The factory tool accomplishes step two and three at the same time. Everything is usally stuck on older engines.

PM me if you are still looking for the climate control pieces.

you might be dealing not with the Chain tension, but with the chain Guide Tensioner, which is located low behind the timing cover. These chain guide Tensioners have a vinyl piece that exerts pressure against the chain, keeping it taught. Aging takes its toll and the vinyl piece desintegrates, leaving just the steel tensioner part scraping against the chain, making the kind of noise you describe.

The chain guide can be replaced without removing the engine from the car but it takes someone with experience doing it. Lots of dismantling to do, including radiator and oil pan.

Jose, that sounds about accurate as a description of this particular problem. At best guess I can surmise the vinyl piece finally fell off a couple days ago when my dad and I first noticed the sound.

I take it this problem could be detrimental to the life of the timing chain, and possibly greater engine problems later on if I don't fix it before driving it again.

As both my dad and I are mechanically inclined, I'm pretty sure we can accomplish the work of dismantling the front of the engine, as long as we don't need special weird tools to do it.

JagTech - Thank you for your reply as well. I've looked online for the tool needed in your description, and it looks like a hollow tube with a handle that slides through two holes at one end of the tube, and a flat round plate at the other end with two small studs poking out of the plate on either side of the opening.

Also, I'm not going to worry about the aesthetics of the interior quite yet with the addition of the climate control face plate...the gremlins are still mucking around in there and I need to get them taken care of first.

you can manufacture your own upper chain tensioner with the instructions in the following link: (about $1.00 for parts and a lot of sweat).

http://www.jcna.com/library/tech/tech0030.html

Also, I would order the Factory Shop and Parts Manual CD, this is not a guessing job. Best to follow steps and procedures. The parts are not expensive. You can order the Jaguar Manual in several places:

http://www.jaggraveyard.com

http://www.lbcarco.com

or call a local Jaguar dealership.