EGR Valve

[dawsy 22]

Hi all could anybody on here tell me what effect a faulty or not working egr valve would have on my 2.2 c5,since changing the swirl valve diaphragm some time ago I have had a leaking air sound when I accelerate the car seems to have very little power to what it had before changing the diaphragm ,I have checked all the intercooler pipes and intercooler for leaks and can find no trace at all,the pipes have quite a lot of oil in them but considering the car has done over six thousand miles in this condition and not having proper boost to remove the oil from the pipes I have put this down to oil getting past the turbo bearings,the whole situation is very frustrating as the car lacks power for overtakes and hills,it is a great car but its a shame i cant rectify this fault any suggestions would be much appreciated Regards Ian

[Monkeyfeet]

Hi again dawsy 22. If the egr is stuck partially open it definitely affects pick-up and the general smooth running of the engine. If stuck open it could do as you describe. I bought a £4 manifold blank off-plate from ebay, took 5 mins to fit, runs better now, I'd recommend this anyway, plus you could eliminate the egr as the cause..............

[dawsy 22]

Cheers for that monkeyfeet I have found it on the bay and will order one for £4 its got to be worth a go,I would like to thank all the people who have posted replys to my questions,without your help I would probably have scrapped the beast Regards IAn

[dawsy 22]

Just one more question about the EGR valve does it require vacuum to open it or to close it Regards Ian

[KevMayer]

On the 2.2 Hdi the EGR defaults to closed. It needs vacuum to open it.

[Lighty]

If you can here air escaping, I would suggest getting a smoke test done, it's amazing how this can show up leaks that you couldn't find before from hoses etc.

[Monkeyfeet]

Dawsy I agree, this forum's a brilliant source of help and info, it's helped me loads.
ps - you'll be able to remove some vacuum piping and plug the connection to the egr piping (bulkhead), eliminate more potential leak sources.

Lighty (sorry to butt in here) can you tell us more about doing a smoke test please?

[dawsy 22]

Morning all,well I have been out this morning and blanked off the egr using a improvised blanking plate (two pence piece)and I still have the air leak sound,so I to would like to know more about doing a smoke test and can you do it yourself? Regards Ian

[Monkeyfeet]

Did you blank off the egr at the inlet manifold with the coin?
Inspired thinking definitely, but this wouldn't change any leaking in any vacuum control circuit would it?
Air leak sound? This does bring us back to the inlet piping really - anybody advise if you'd actually hear a vacuum leak with the engine running?

[dawsy 22]

Sorry monkeyfeet my description of the sound was lacking somewhat the sound of the air is best described as compressed air from the turbo,it is louder when the car is being driven which I would put down to different demands when the car is being driven under load rather than stationary,if I drive down my street which is terraced it sounds even louder when bouncing of the houses,it is best described as the sound from a dump valve as I am typing this my thoughts are where is the dump valve if there is a dump valve fitted where is it? The egr was blanked of at the manifold end the two pence piece was the right size to blank it off my thinking was that if the fault was the valve sticking the coin would blank of enough for me to notice a difference in the sound the car makes and its performance,as it turned out the coin seal was air tight.One other trai of thought I have been having was when I changed the swirl diaphragm I forced the black turbo air intake tube to one side to give me access to the diaphragm there seems to be a lot of pipes attached to this ,any tips on how to remove this ducting so I can check what,s behind it,again thanks for all the advice and tips guys it is what makes C5 ownership bearable Regards Ian

[KevMayer]

Hello Dawsy,

If you hear a loud hissing then you definately have a boost leak. The air is compressed by the turbo to up to around 17 psi which is a lot of pressure.

The turbo outlet pipe runs from the turbo (turbo mounted at the back of the engine) forwards under the engine to the intercooler which is on the right hand side of the radiator ( looking from the front bumper with the bonnet up). There's a T in the pipe just before the intercooler where a branch bypasses the intercooler. This bypass runs through a heated water jacket and is part of the FAP regeneration system. The bypass pipe and the pipe from the intercooler meet at an interconnector just before the inlet manifold. This interconnector has vacuum actuated flap valves which are used to open and close the bypass and intercooled air passages.

So, somewhere along all this air pipe you have a leak. Probably a loose jubilee clip, but maybe a split in a hoze.
Look for signs of oil because you'll have lots of dirty black oil coming out of the leak in the pipe.

The C5 2.2 Hdi doesn't have a dump valve. Diesels don't need dump valves because they don't have a trottle butterfly like a petrol engine.

On a petrol turbo engine a dump valve is used to keep the turbo impeller spinning when the throttle butterfly shuts otherwise the sudden abrupt cut off of air flow would cause the turbo to stall. The dump valve whistles as boost pressure is released when the butterfly shuts when the driver lifts off the accelerator.

[dawsy 22]

Cheers Kev I have checked all pipes for leaks and the intercooler,all clips are now tight and I can see no sign of any oil on the pipes or the intercooler I have changed the short pipe from the turbo to the pipe that goes under the sump ,I keep getting drawn to the bulkhead side of the engine as the noise seems to come from there Regards Ian