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    EGR valves

    I know this has been discussed as a side issue in other posts but today I had an email from a friend who is a real engineer. He has fitted several Mercedes diesel engines to other vans - one to a Ford Transit and another to a DAF Sherpa van so I respect his opinions and abilities. In addition he has converted a Ford Transit to hybrid electric power. I have just bought a 3 year old diesel Golf and asked him if he knew where the EGR valve is on it so I could see if I could block it off with a blanking plate.
    He has recently scrapped a diesel Mercedes and out of interest he took the EGR valve off to take a look. The car was coughing and spluttering and returning a terrible MPG. He included in his email to me:
    When I blanked the W210 EGR valve I could see that the manifold was choked to about half of it's correct diameter...
    I am worried that when they design diesel engines to meet the current emission standards, they are working with brand new engines, and then the EGR and DPF systems work just fine. However after a few years the whole air inlet system gets blocked up and the engine cannot work properly, as it was designed to. Therefore the pollution will increase to a level way beyond what it would have been without the EGR system in place. So my 'ever so 'umble opinion is that I would like to block off my EGR valve in order to preserve a reasonable level of emissions, and to keep my MPG above the 30 level. The alternative, if you leave your diesel engine as the manufacturers made it, you will be spending in excess of £1000 having the head and inlet manifold and EGR valve removed and cleaned out, just as we would have de-coked an engine in the 1960's.
    You can see photos of examples of blocked inlet manifolds if you look on ebay for 'EGR blanking plate'.
    I respect the fact that some in the forum regard the diesel particles as injurious to health, but surely the fact that the engine loses its efficiency in probably 50,000 miles will produce far more pollution than one without the EGR system. I think it is possible to completely remove the EGR valve, but you have to be a bit of an engineer to do that, and you have to re-program the computer as well so I have no intentions of doing that.
    suivez l'aventure

    #2
    Is that suggesting that blanking the egr after a considerable mileage is unlikely to be as effective as might be expected due to the head being coked up?

    Comment


      #3
      mines done over 200,000 miles with the egr valve not blanked off and i still get 58 mpg on average so i'm not positive if you drive correctly that the egr valve is a hinderance

      course I drive like an old man trying not to go over 60 and then wondering why i'm doing eighty

      Comment


        #4
        Originally posted by Dapple View Post
        Is that suggesting that blanking the egr after a considerable mileage is unlikely to be as effective as might be expected due to the head being coked up?
        No! it is not the head that "cokes up". It is the valve - when it opens it is returning exhaust gas to the inlet manifold to be burned a second time - if I recall correctly - the theory being this reduces nitrogen oxide emissions - something not checked during the MoT.

        If your vehicle starts to smoke when you press the accelorator under load (get someone to follow you - if they see a puff of black smoke as you start going up hill) then the EGR needs to be either cleaned or blanked off.

        Kyran there are 4 possibilities (I think)
        1. you always use good diesel - not cheap supermarket stuff that has less detergents;
        2. your driving style is just right and you keep the engine "clean";
        3. when you go for a service your garage cleans out the EGR valve;
        4. Of course if you did not buy your van new maybe a previous owner blanked / disabled the EGR valve.

        All I know is I have owned several vehicles that may have failed their emmissions without blanking the EGR. When I had a caravan I got my Pajero for a song - it was going to fail its MoT on emmissions - a week later and a blanking plate - it sailed through its test.

        Jon
        Amor omnia vincit et nos cedamus amori
        https://smallromahome2oldies1largedog.blogspot.co.uk/

        Comment


          #5
          Thanks jon, that is a nice summary. I am puzzled though as to how blanking off the Pajero when it is already going to fail would make a difference, the only thing I can think is that the EGR valve was actually faulty but the inlet system was not blocked.
          I don't think that removing and cleaning the EGR valve is part of a service, though you could of course ask them to do it as an extra. I'd be interested to know what that would cost, I suppose it depends on the location and ease of access to the valve. However if the EGR valve was bunged up, then the passage all the way from the valve to the piston crown would also be constricted by carbon build up. I have dismantled many petrol and a couple of diesel engines, and even without EGR valves, the carbon build up made the air flow very restricted.
          Jon's second point is good I think. I 'think' (but am not 100% sure) that the EGR valve opens on heavy use of the accelerator and it is then that the exhaust gets blown back into the inlet system. If that is the case then driving gently should minimise the problem. The only thing wrong with driving gently is that you risk blocking up the DPF. You have to do occasional drives at least at 60mph to regenerate the DPF.

          Dapple: I would think that blanking off the EGR valve at any stage would at worst keep it at the stage it is when blanked.

          On some engines a total blank works, but on others the blanking plate needs a small hole to let a little bit of exhaust through. On my last motorhome, a Euro4 engine, a total blanked plate worked fine, but on this one, a 'Euro 5 Plus' (whatever that is!) when I fitted a blanking plate, the computer didn't like it and I had to 'limp' home. Then I drilled a 10mm hole in the plate, refitted it and the computer is quite happy now. Mind you, I do try to stick to 60, but have once or twice gone to 70 to get past a rolling road blockage of trucks on a motorway.

          I think that at some future point there will be a worldwide 'revelation' that although the EGR system works on a new engine when emissions are tested, that as mileage builds up, the emissions degrade hugely.
          Last edited by gasgas; 10-02-2018, 09:05 AM.
          suivez l'aventure

          Comment


            #6
            My last 5 company cars were all diesel and replaced after 100K miles with the engines running sweetly. Mostly used on fast roads burning cheap diesel..
            ​​​​​Since retirement my milage has dropped hugely and the economic case for diesel has vanished. Also my inner geek insisted on going hybrid.

            Worth noting that the MOT emissions test is being tightened up soon to catch people who have removed the DPF. I expect one day they'll be testing for NOX too.
            This article seems quite sensible.
            Last edited by jondxxx; 10-02-2018, 10:29 AM.
            Isaiah 45:8

            Comment


              #7
              I'm a fan of diesels ever since we were first threatened with Unleaded and what damage could be caused to certain engins if we didn't put additives in our fuel. The Authorities wouldn't even tell us which engines were at risk and which were safe to run on the stuff. Tha case is still the same with ethanol. we are told that it can desolve certain metals and plastics, but we are left on our own to find out if it will kill our engines. I think that the extra mpg I get from burning diesel must reduce the amount of muck I thow out through my exhaust.

              I also think that EGR valves were designed to work on a brand new engine so that the manufacturers can claim fantastic results and sell more cars to an unsuspecting public, and I'm pretty certain that a blocked EGR will cause more pollution than an unblocked one, or a blanked off one. I haven't measured the surface area of the inside of the induction piping, but the exhaust gasses must pick up a lot of old muck as they pass through the system. This is a self generating process and the longer it continues, the more muck will be fed into the engine.

              This will reduce the burning effeciency of the fuel and lead to a dirtier exhaust.

              If the EGR is blanked off, Cleaner fuel will be burned in the engine and that will result in a cleaner exhaust.

              Perhaps an alternative would be to bypass the EGR valve altogether, and collect the dirty sediment in a seperate container to be disposed of in the same way as we dispose of old engine oil?

              Comment


                #8
                This is all beyond me to decide on rights and wrongs, but my new euro 6 doblo has one of those engines that avoids adblue by passing the exhaust through the dpf and turbo BEFORE the egr valve transfers exhaust to the inlet. I am hoping the the exhaust after the dpf is clean enough of soot to not clog up the egr so quickly.

                Comment


                  #9
                  Originally posted by gasgas View Post
                  Thanks jon, that is a nice summary. I am puzzled though as to how blanking off the Pajero when it is already going to fail would make a difference, the only thing I can think is that the EGR valve was actually faulty but the inlet system was not blocked.
                  .
                  What happens is when the EGR cokes up - it jams in the open position - the flap linking exhaust and inlet is fully open at all times. hen it is noy coked up it is closed at idle and slowly opens when you go to full throttle - there is a damper - so when you floor the GO pedal the flap remains closed for a period then opens slowly.

                  The pre computerised system used 2 inputs - throttle connection - and vacume pipes.

                  My practical knowledge was gained on the Pajero 2.8 and the Ford Transit and LDV 2.5 DI engines

                  Jon

                  Amor omnia vincit et nos cedamus amori
                  https://smallromahome2oldies1largedog.blogspot.co.uk/

                  Comment


                    #10
                    Thank you Derek and Jon, it sounds as if you have a decent knowledge of how the EGR works. I knew that Fiat don't use AdBlue to achieve Euro6, and it is one reason why I would prefer a Fiat over others, including Citroen and Peugeot which do need AdBlue. It might be the case that non-Fiat, and earlier systems will choke up the EGR and inlet manifold whereas the later ones won't. Time will tell. I see from Ebay that a typical price for a new EGR valve is a bit over £100 which is not in itself terrible, after all a silencer in the exhaust for a very ordinary car can cost that, and we don't baulk at that. The problem would probably be if a new EGR valve is needed then the inlet valves are probably bunged up as well. Thank you for your inputs, I don't think I will bother trying to fit a blanking plate to my Golf.
                    suivez l'aventure

                    Comment


                      #11
                      Here's a youtube you might find interesting regarding EGR valves and engine performance, https://www.youtube.com/watch?v=H4Mo9aD1Ecw
                      I only found it because I have the Hyundai load, but I guess it's a similar story with other Diesel engines.Personally I stay in a lower gear to work the engine if the vans not had a good run for a while.
                      ps

                      Comment


                        #12
                        That was interesting Johnnieboy. I was a bit surprised that they couldn't clean the valve though. I would have thought there is a decarboniser chemical that it could be soaked in. Specially as I think he said the EGR valve was ?was it a thousand dollars?. I have seen a selection of EGR valves on ebay for something around £130 ish which you could accept as part of the exhaust system and if it lasts 100,000 miles that isn't too bad. I did notice that he did a decarbonisation process after fitting the new one, so wonder why he couldn't have done that before. You can get spray cans of EGR cleaner I believe. It's a pity the video recordist didn't put a sock over the microphone so you could tell what the guy was saying. Some EGR blanking plates have small holes in them, and seeing this video sounds as if a blanking plate with a small hole will still open the valve but more slowly and so let less exhaust through.
                        suivez l'aventure

                        Comment


                          #13
                          In another video he cleans the EGR so in this case he must have decided that the valve was likely to be faulty rather than just dirty. I think that cleaning is probably the sort of messy job that garages don't like. If it doesn't work then it can be tricky getting the customer to pay for the wasted labour.
                          ​​​​
                          Last edited by jondxxx; 17-02-2018, 11:56 AM.
                          Isaiah 45:8

                          Comment


                            #14
                            I cleaned mine out with white spirit. It was difficult to get into all the crooks and nannies and I'm not sure how good a job I did. There was a slight improvement in performance but not enough to be noticable. I think a good blathering with WD40 may be the best treatment. It's supposed to desolve more or less anything so I will have a go at that when the weather improves. Otherwise, it's the blanking plate.

                            Comment


                              #15
                              Myke- I think the EGR has to open and if it doesn't I think there is a sensor in there which sends a message to The Computer. If The Computer doesn't like it, it will go into Limp Mode.
                              Presumably it opens under exhaust gas pressure - the more exhaust gases, the more it opens? Like an SU carb. So, like a company that sells cigarettes to smokers, it works by killing off its enabler.
                              suivez l'aventure

                              Comment

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