16v HDi inlet manifold removal

Citroen C3 2002-2009 16v HDi engine has a plastic inlet manifold the links into the EGR system.

The Citroen C3 HDi inlet manifold (here) may require cleaning, or more easily, a replacement if the EGR system has failed, coked-up and restricted the inlet.

You also get access to the inlet valves for inspection and possible cleaning with the inlet manifold removed.

The job also requires removal of the C3 HDi Crankcase Ventilation system (PCV) which is included here[/urll]


Disconnect MAF electrical connection and remove the air-filter box and MAF



Remove the EGR pipe from each end and the middle fixing, you may already have this removed and noticed it is restricted that lead you to removing the inlet manifold.

EGR pipe disconnected from inlet manifold after disconnecting from EGR valve and centre fixing point.


EGR pipe removed and shows a contamination build-up of oily carbon deposits restricting EGR flow.



Remove the large electrical connector mounting on the left of the engine and the MAP sensor connector.

Remove the PCV in this topic



Remove the intercooler pipe, it may be stuck and some penetrating fluid works well for this.

Disconnect the injector leak-offs and injector electrical connectors.

Disconnect the injector pipes from the top clamps, the rear common rail (just the injector pipes) and with the PCV removed, disconnect the injectors from their pipes.


Cap off all 8 connections and keep the pipe ends clean if they are to be re-used. You don't want any dirt entering the injection system at this point after the filter.


With the injection pipes removed there are some bolts to remove all except one is accessed from above, one is on the timing belt side and some are already removed because they also fix the PCV system that as already been removed from the engine. The hidden bolt is under the electrical connection mounting.


The manifold is sealed with o-rings so with all the mounting bolts removed the inlet manifold will lift up with a slight lever to break the o-ring seal. Lift the inlet manifold away to reveal the inlet ports.

Replace the o-rings (here) before refitting the inlet manifold and PCV. The 8 (4 large and 4 smaller) or-rings will fit many of the HDi engines, the square o-ring is used on the 1.6 16v HDi but is not needed on the 1.4 16v HDi.

Part numbers for the inlet manifold o-rings are 0263.7H 0348.R5 and 0348.R4

Refitting the inlet manifold.

Obviously now is the time to clean the cam over o-ring seating points to ensure a good seal if you haven't been cleaning the inlet valves

The inlet manifold refitting is aided by lightly greasing the orings with some silicone grease (eBay - here) this ensures the parts slide together and don't get snagged or twisted to make sore the orings can proved a long-lasting seal.

There are two bolts that are slightly shorter than the others, use these in conjunction of the longer ones to tighten down, gradually the inlet manifold. The shorter bolts are ideal for the front fixings that usually have the PCV on. The short bolt will allow full tightening of the front as you evenly tighten the manifold down. Reuse the short bolt in each of the front positions than need it, leave the long bolts in place.

Fit the short bolt on the timing belt side.

Refit the injection pipes and pipe clamps

Then refit the leakoff pipes and injector electrical connectors

Next refit the PCV crankcase ventilation and oil filler cap unit with the other longer bolts,

Then attach the electrical connection mount, EGR pipe, MAF, air-filter box and its associated pipes

The diesel system will need priming using the hand priming pump, but even after that, the engine may take a lot of turning over to start.