1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

W220 S320 CDI Lack of Power Clogged EGR valve and inlet manifold

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by paulkno, Mar 1, 2018.

  1. paulkno

    paulkno New Member

    Messages:
    7
    Likes Received:
    4
    Joined:
    Apr 3, 2017
    Location:
    Manchester
    Your Mercedes:
    S-Class W220 2002 320CDI
    I've seen lots of talk about this but no solid solutions, just a lot of possibilities. So I thought I'd share mine.

    Essentially I was solving the lack of power problem that many cdi owners talk of. The symptoms are the car is driving normally then when you demand more power the car just trundles along and hardly accelerates. It may rev up but your don't really go anywhere and have a serious lack of torque. If you stop and turn the engine off and on again it drives fine, for a little while. If you never asked for serious power you could drive for miles without noticing there was a problem. Then as soon as you go to pull onto the motorway or overtake something you realise there is absolutely no power.

    Many owners talk of EGR problems and limp modes. However in this case there is no error msg or code stored to be read. ie this is not limp mode and the car is assuming that all sensory data is correct.

    The EGR valve on this 320cdi engine is vacuum operated. I opened up the valve and of course it was well clogged with soot. It is totally possible to clean and free up the EGR valve. Very easy to access on top of the inlet manifold with only three torx screws holding it together. It's worth noting that the valve is in the mixing chamber and not the removable vacuum operated actuator. Both will need cleaning and freeing up. I figured if these were clogged then the inlet manifold is sure to be also.

    There is a solenoid on the bottom of the inlet manifold that operates flaps inside. You can check the operation of this by manually moving the solenoid and seeing if it moves freely. Chances are if your inlet is clogged then the flaps won't budge and/or the ball and socket joint on the solenoid has slipped off while it was trying to open the jammed flaps. A sure sign you have a clogged manifold. This vehicle had done approx 140k miles and is a 2002 S-class.

    I removed the entire manifold assy. I did this from above without ramps, however I wouldn't recommend it. It's a long fiddly job with very restricted access. The fuel rail and filter will need to be partially removed for access. Also there are 8 wires routed between the manifold pipes, so you'll have to unplug all these. One goes to the gearbox, another is an earth for the starter motor, another to the manifold pressure sensor and one to the (I'm gonna call it a water pump) I'm not sure exactly what it does but I'd love to so if you know... it is mounted to the underside of the inlet manifold and brings water through the egr cooler. This will also have to be disconnected and removed. Very tricky from above with spring clips holding the water pipes on. The EGR cooler also has to come off, don't drop the gasket at the exhaust end, the down pipe and EGR end are push fit. Then at the front there are further wires to the oil level sender on the sump (has to be unplugged from underneath, you don't need ramps but the trays will have to come off. Although you've probably already removed these to collect all the screws and ratchets you've dropped). Now theres a wire to the solenoid, another to what I think is a unit to do with the brakes or water system (can't remember off the top of my head but its NSF corner). And a finally a wire to the sensor on the air pipe from the turbo side.

    Once you've removed all the torx nuts holding the manifold on you can wriggle it out and you'll probably find its almost totally clogged. Out of all the inlets this one only had about three that weren't blocked and the flaps we're totally jammed.

    I cleaned it all out, freed up the flaps and refitted. Now it pulls like a train all the time.

    Once refitted the engine will need repeated cranking as the fuel was disconnected. Make sure you have a battery boost handy, eventually it WILL start. You'll also need to top up the coolant as you'll have lost some from the weird water pump thingy mounted to the bottom of the inlet.

    Unless you are fairly competent, have good tooling and are brave, I wouldn't recommend doing this job at home. If you have access to ramps or a pit, its much easier.

    Basically if you have these symptoms, check the vacuum to the EGR valve. Clean the EGR valve. Check the inlet flaps can move. If the inlet is blocked ask your mechanic to remove it and clean it or if you're made of money replace the lot, but the valve on its own from Mercedes is £575. I expect the inlet manifold isn't much cheaper.

    You could also try changing the airflow meter and air pressure sensor, as they're cheap. However these tend produce slightly different symptoms.

    This is not the first W220 S320 CDI I've seen with this exact issue. In all cases its been a clogged up inlet system with jammed swirl flaps due to the EGR valve.

    Hope this helps some people. Enjoy
     
    om613 and moj91 like this.
  2. moj91

    moj91 Senior Member

    Messages:
    227
    Likes Received:
    11
    Joined:
    Jul 12, 2013
    Location:
    Northamptonshire
    Your Mercedes:
    '09 W204 C-Class 250 CDi, '05 W220 S-Class 320CDI (AMG Kit), '03 W168 A-Class 170CDI LWB Elegance...
    We are looking at doing this on our '05 S320 Cdi, 240k miles atm, as we have similar symptoms and EGR fault codes. My brother wants to attempt it, although he is competent i think it may be a little more than he can chew/be bothered with - i would suggest letting a garage do it but i don't know if they will take the care/time needed to do it properly. If we do it I will report back our experiences for the benefit of everyone else also. Great write up, thanks paulkno!!!
     
    Wighty likes this.
  3. moj91

    moj91 Senior Member

    Messages:
    227
    Likes Received:
    11
    Joined:
    Jul 12, 2013
    Location:
    Northamptonshire
    Your Mercedes:
    '09 W204 C-Class 250 CDi, '05 W220 S-Class 320CDI (AMG Kit), '03 W168 A-Class 170CDI LWB Elegance...
    Wighty, what did you use to clean your manifold/egr out? Brake cleaner/clutch cleaner? Something more readily available? Did you fashion any tools to clean inside the manifold?

    Thanks
     
  4. davemercedes

    davemercedes Senior Member

    Messages:
    2,276
    Likes Received:
    518
    Joined:
    Jun 15, 2012
    Location:
    Worcs
    Your Mercedes:
    2007 Merc 220 CDi Est Auto Av
    This is a very interesting thread - thanks guys!
    - But I don't like it cos it spells out tomorrows problems for me!

    Good luck moj91 (I won't say "enjoy" but enjoy it after it's done)!
     
    moj91 likes this.
  5. Wighty

    Wighty Senior Member

    Messages:
    4,443
    Likes Received:
    1,932
    Joined:
    Aug 4, 2016
    Location:
    Sunny Essex
    Your Mercedes:
    W211/E320cdi/2009 and CLK200k 2009
    I use egr cleaner on the egr when I take it out yearly . I've never taken the manifolds out on mine yet out hasn't needed . I have fitted the resistor modification to the swirl flap motor so I shouldn't have to for a while .
     
  6. oigle

    oigle Senior Member

    Messages:
    2,806
    Likes Received:
    145
    Joined:
    Mar 15, 2005
    Location:
    Redcliffe, Queensland, Australia
    Your Mercedes:
    Currently 2003 ML270. 2012 Nissan Maxima 250SL.
    I did all that years ago and then deleted the egr from the system. That stopped the crap getting in so the flaps continue to work perfectly 100K later. Car runs perfectly. Mine is a 270 motor but has same vacuum operated egr.
    Ian.
     
    davemercedes and Wighty like this.
  7. davemercedes

    davemercedes Senior Member

    Messages:
    2,276
    Likes Received:
    518
    Joined:
    Jun 15, 2012
    Location:
    Worcs
    Your Mercedes:
    2007 Merc 220 CDi Est Auto Av
    Isn't it illegal to remove the EGR now?
     
  8. moj91

    moj91 Senior Member

    Messages:
    227
    Likes Received:
    11
    Joined:
    Jul 12, 2013
    Location:
    Northamptonshire
    Your Mercedes:
    '09 W204 C-Class 250 CDi, '05 W220 S-Class 320CDI (AMG Kit), '03 W168 A-Class 170CDI LWB Elegance...
    Supposedly it is illegal - unless the emissions are over the threshold i cant see it being a problem in the sense that the EGR cannot be seen with the engine covers off, and the MOT chap isnt allowed to remove them to inspect.
    I can see the point, but at the same time our friendly MOT chap said he would love to be able to remove the undertrays as many issues could be lurking unknown to us. Ahh well.

    We havent tackled the inlet manifold yet as the car is off the road with a split radiator and a badly leaking oil cooler gasket which need attention 1st. We have bought a nissens Rad as the MB one was over 2x price, but the nissens one is missing some square nuts, which they say arent supplied with the Rad, and MB say they arent available as a spare part. I think we will just cut some stainless bar and tap it to make some. All faff and effort for what should be a simple job!! I dont have the time haha.. anyway, i digress. Currently looking into the swirl flap resistor mod!
     
    davemercedes likes this.
  9. davemercedes

    davemercedes Senior Member

    Messages:
    2,276
    Likes Received:
    518
    Joined:
    Jun 15, 2012
    Location:
    Worcs
    Your Mercedes:
    2007 Merc 220 CDi Est Auto Av
    I get so angry about stupidities like that... in a former life as a Parts Manager the workshop supervisor used to create a daily "hold up" list of parts that were keeping vehicles off the road... One day he came in with almost the same thing as you mentioned - square cage nuts off a front wing where similar had happened. I went round the back of the shop and found the old wing on top of the scrap pile and and took it to the guy who did most of the welding. In 2-3 minutes he removed all six for me. My timing was perfect - I was able to catch the supervisor with four mechanics in his hovel (I mean office) where I tossed them down and told him he should have supervised the job properly and swapped them over! I once had the same stupidity over a paper transmission gasket (which was a real factory shortage item) and found the old unit and carefully peeled it off in one piece and told them to get on with it!

    I sometime imagine a mechanic serving with the Desert Rats getting shot for making a daily back order list like this!
     
    Wighty likes this.

Share This Page