I think we have all seen the examples, and in some cases experienced the effects of EGR valve contamination, including soot build-up into the EGR inlet manifold circuit and even post EGR valve.

Now the EGR route will be rich with carbon/soot but what interests me is how contaminated the whole engine inlet manifold and valve ports get?

Main air intake is off course via the normal air filter induction route but how contaminating is the EGR circuit creating in the inlet tract / chamber and this should be a concern?

Has anybody stripped down a modern turbo diesel with EGR recurcutlaion and can comment on relative EGR circuit crud compared to inlet crud build-up.

Hi mate,

On the 1.9 JTD, when I removed the inlet manifold, there was a build up of about 5mm thick of the same sludge/soot/gunk that you get around the EGR valve, which would almost defiantely have decreased the air intake volume. I scraped off as much as i could and then had to soak the whole manifold in thinners overnight to get the rest off. Have seen this on several JTD's and a few other makes of turbo diesels. Think i have some piccs somewhere, will see if i can dig them out.

Alan

I'd imagine the backs of the inlet valves are interesting too......

Well I feel a modification comming on.

Disconnect the EGR tube from exhuast manifold (either end). Block off exhaust exit. Fit cone air filter to EGR intake circuit or tap back into air intake post air filter and pre turbo charger.

So justification (tounge in cheek). Euro 4 Diesel was not legally required till Jan 2009. (I think this date is correct). Fiat chose to experiment in 2005 and now problems are arising. I gather update EGR valves are available.

I'm fairly confident my Croma will pass UK 2005 emissions regulations (without DPF and EGR) so if they are going to cause me grief, malfunction and additional costs then I'll re-engineer the car to meet those legal requirements appropriate to legislation at registration.

I can't help think that recirculating extensively contaminated soot laden exhaust fumes is actually unvironmental and in the long term bad. Replacement EGR valves, engine decoking, trashed gaskets, consumed cleaning products etc. etc. is not a good idea.

However, IF the EGR was taken from post DPF then much of the EGR emmisions benefits would be achieved with little degradation in emmisions. The only thing that I suspect stops the manufacturer doing this is cost of plumbing from post DPF back to inlet manifold.

So the cheap solution allows manufacturers to meet test levels, but takes no account of long term additional costs/landfill/etc/etc of discarded parts. Cost is put into the aftermarket etc..

I have no problems with real green engineering but I do, have done and will continue to oppose half baked solutions.

With regards to diesel engines there I would offer an additional view. Ignoring the expensive post DPF EGR recirculation.... why is diesel so expensive. It is far easier and cheaper to refine than petrol but we pay far more for it. Swop the costs. Make diesel really cheap and we may be more receptive to the additional maintenance costs of running a modern Euro 4, soon possibly to be Euro 5, diesel engine.

Just dragging up those old thread, to ask:

Hellcat said:

I'd imagine the backs of the inlet valves are interesting too......

Click to expand...

What made you say that?

I ask because my Panda has had EGR valve problems, followed by a misfire caused by low compression. A compression test was low on cylinders 3 & 4, and there are thoughts that the valves might not be moving freely.
To add to this, Porsche have recently moved to direct injection on some of their engines, and I've seen a picture of an inlet valve where the back of it had a lot of carbon build up. With injection into the manifold you get the fuel vapour flowing into the cylinder over the valve. With direct injection you don't.
I'm starting to get a but concerned about the whole idea of EGR and direct injection now...

I said just for that reason.. if the EGR, and intake manifold are coked up - then the next thing the sooty air meets is the intake valves.

after decoking the inlet manifold and especially the butterfly valve for the second time I blocked the egr tube with a piece of stainless steel cut from an old ss sink and disconnected the arm to the butterfly valve so it is permanently open....that was tens of thousands of miles ago...noticeable and sustained increase in performance and an extra 2-3 mpg....this is on a 1.9 JTD 110

tinytim said:

disconnected the arm to the butterfly valve so it is permanently open....

Click to expand...

I'm guessing you mean the vacuum-operated throttle butterfly just before the EGR entry into the manifold? It has nothing to do with the EGR system/emissions.

To those who need to clean their engine parts. Citric acid is ok on aluminium (AKA Cillit Bang) but not so good on steel/iron.

Caustic soda (Sodium Hydroxide) will eat soot and is OK on steel/iron. But - DO NOT use caustic cleaners on aluminium parts - they can be damaged very quickly.