The Citroen CX Workshop

Citroën CX - Retrofit of Alumininium Intake Plenum

Retro-fit Aluminium Intake Plenum

The plastic CX intake plenum commonly fails. As a preventive some owners decide to fit the older all aluminium plenum. One could be excused for believing this is a simple bolt-on procedure, that certainly was the thought here. However, there are a few issues that this document will reveal, and how to resolve them.

This plenum was fit to a 1985 CX Prestige with the automatic transmission, so will apply to any later CX with the automatic. Manual transmission cars will have the engine mounting problem alone, easily addressed.

The Retro-fit

Now you have an aluminium plenum. But you will discover the mounts for the engine don't line up, nor will the automatic transmission kick-down cable mount properly. You may also need to swap the throttle pivot plate and the connecting linkage. This is not a difficult process, the images capture everything.

The mount position is incorrect. While this is fixed with a modification it may be possible to track down the original mount bracket.

The fix is a small metal plate positioned so the stud fits the aluminium plenum. Use two nuts to secure the stud to the plate. Locktite is recommended so removal of the plenum is easy.

The kick-down cable bracket must move away from the throttle plate end.

Overall view of the modified aluminium plenum.