No current thread for the repair of the vacuum advance pod on the v12 distributor. Vacuum advance is the function, when it gets vacuum it advances the timing, when vacuum drops it retards it.

How do I repair a leaking vacuum advance module?

 

Hi Ivan,

I have moved your post from the forum for the XJ40 to the forum for the XJS. Here you will find knowledgeable owners of similar cars.

I assume you have checked for leaks in the vacuum hoses and air filter? If you have confirmed the vacuum capsule has failed, I don't know if it can be repaired. Hopefully some of our members will know. If it must be replaced, I believe new aftermarket units are still available from independent Jaguar parts vendors like our forum sponsors SNG Barratt, Coventry West and Jagbits.

Cheers,

Don

 

http://www.jag-lovers.org/xj-s/book/XJS_help.pdf

Page 132

If you haven't read Kirby Palm's book I highly suggest you find time to read it cover to cover. It's considered by many to be THE book for the xj-s. And it's a good read.

 

You cannot. Buy a new one from Manners, SNG etc.

 

Britishvacuumunit provide beautifully remanufactured, and adjustable, Lucas units. FYI.

 

I took mine apart a few years ago when it failed, I could see no way to fix it. Once the diaphragm material is cracked or torn, it's all over.

Before doing that, try pulling a vacuum on it and see if the mechanism moves. But given the age of the car (I have an 87) if it hasn't failed yet it probably will soon.

While you're in there, follow Palm's recommendations on reworking other parts of the distributor. And, as stated above, read the entire thing when you get the chance.

Cheers,

John
1987 XJ-S V12

 

I would just simply replace it as well. Much more straightforward and reliable of a solution. However the question posed was how to repair it and I recalled reading about a method of using the innards of a generic chevy advance inside the Lucas unit from Palm's book which is on page 132

 

After posting I read the section of the book. Gonna hillbilly Bob it and uses the guts of a hei setup which I have.