Greetings;

I will be changing timing chains and tensioners on my 99 XK8 4.0 convert.
Is there anything special I should do or lookout for when I pull the Valve Timing Units? I noticed in the diagram on the Bush Carriers it looks like there are two seals. With 80,000 on the car should they and the Valve Timing Units be replaced. Do these unit fail very much?

Thanks
Mitch

 

Mitch,

I've changed your thread title from your forum ID to the subject of your question.

Graham

 

Thank you Graham
Mitch

 

You should replace the seals because...why risk re-using brittle old seals when you have the engine apart? I used neoprene/rubber seals that I matched from the plumbing aisle at Home Depot. Don't know if this is recommended (my local Indie mechanic thought it would be fine), but the Jaguar seals were hard to find and really expensive (maybe 20 bucks or so for a tiny O ring). So far, so good...

Regarding whether or not the bush carriers and VVT tend to break? I haven't heard of this problem as a matter of course, though I found a broken bush carrier when I did my valvetrain work, likely caused by over-torque-ing from the last amateur mechanic who had a look. I bought a used replacement on eBay.

Some of the more adventurous DIY and pro mechanics on this site have worked on the VVTs and described their overhaul, but as a true amateur wrench, I regard these parts as units that were designed by Harry Potter and his wizard friends. They have lots of springs and tiny mechanisms are to be avoided in my playbook.

 

Truck Graphics; Thank you very much for the info. The tip about HD is great. I would have never considered it. This is my first Jag so I'm asking lots of questions until I get my confidence level up. I'm not new to auto repair. I used to build mostly Chevy racing engines in the 60's. The Forum is the best thing I could ever have found.
Thanks Again
Mitch

 

These engines are quite easy when doing timing chains, no timing marks to line up, etc.


There are files on this forum that give detailed instructions for special tools and procedures for doing the timing chains.


In order to just remove the VVT unit, its held in by an allen bolt. If you can find the seals for them, I'd replace them. As for disassembly, not too bad and yes there are springs inside. Just lay everything out in order so reassembly is easy. Be careful when removing the torx bolts, the springs inside are quite strong.


Haven't seen many of these units go bad to be honest, maybe a handful over the 16 years. Mostly the VVT units on the 3.0LV6 I've seen go bad.


Upon reassembly, clean out the snout of the crank from the thread locker, and reapply with new thread locker.

 

JBzXJ40; Thank you very much for your help
Much Appreciated
Mitch