This is a custom made rebuild kit for Jaguar V12 5.3l; 6.0l Auxiliary Air Valve also known as AAV.
One of the most common problems with Jaguar V12 engines is erratic idle due to faulty Auxiliary air valve (AAV).

Typical symptoms of faulty auxiliary air valve:
  • Cold Idle too low
  • Cold Idle too high
  • Warm idle too low
  • Warm idle too high
  • Hunting idle
Usually AAV piston gets stuck due to galling and/or thermal bulb wears out and gets “slugish” with age and doesn’t close AAV all the way. If the piston got stuck, then most likely thermal bulb was damaged as well so soaking AAV in various liquids or squeezing thermal bulb will not fix it.
This kit will include all the parts you will need for full AAV rebuild:

  • custom made upgraded stainless steel piston
  • custom made upgraded stainless steel spring
  • new correct spec thermal bulb
  • new AAV gasket

I'm not really sure why Jaguar or Lucas used (and still use) aluminum pistons for AAV's, but this is really a bad idea o start with. Aluminum to aluminum has a very high sliding friction coefficient and if prone to galling. Aluminum to aluminum sliding friction coefficient is ~ 1,4 while aluminum to stainless steel is only ~0,5 That's why pistons in my kit are made of stainless steel.

This kit will work with all AAV's used on V12 Jaguars:






Please check my other listings as I have more custom made parts for Jaguar V12 engine.

I can also offer express shipping (extra cost), please contact before purchase to get a quote.