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

Howto: Duovalve maintainance

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by Parrot of Doom, Jun 8, 2006.

  1. television

    television Always remembered RIP

    Messages:
    164,074
    Likes Received:
    277
    Joined:
    Mar 14, 2005
    Location:
    Daventry
    Your Mercedes:
    2002 SL500, 216 CL500, all fully loaded
    There is a very good post on Benzworld in the 140 section with all details of the rebuild of the solenoids.
     
  2. jonclancy

    jonclancy Senior Member

    Messages:
    134
    Likes Received:
    0
    Joined:
    Jan 4, 2005
    The V12 Uberalles link is dead now.

    But I found what looks like the text only reproduced here:

    http://blog.daum.net/gogosmotors/47

    O-rings in the referred size are on eBay. £3.75 per 10-pack

    CODE : OR BS016 N70 (10) BS016-N70 (Pack of 10)

    O Ring Round Section Seal - Suitable for Flanges, Recipricating or Rotary motion.

    Size : I/D 15.6mm x 1.78mm Cross section (5/8x3/4x1/16")

    Material - BLACK Nitrile Rubber 70° Shore Hardness - Working Temperature Approx -40°C to + 110°C
     
    Last edited: Oct 23, 2012
  3. AmacoFL

    AmacoFL New Registration

    Messages:
    1
    Likes Received:
    0
    Joined:
    Jun 23, 2013
    Location:
    Coral Springs, FL USA
    Your Mercedes:
    1996/E320/3.2
    TO: PARROT OF DOOM
    Great job of explaining the process. Excellent pictures.
    I live in Florida and my wife drives my 96 E320. Got in the car yesterday when it was over 90 degrees F. Started it and got blasted with heat from the drivers side vent and the drivers side of the the center vent. Passenger side was working normally.
    Went online looking for answers and I was seeing all sorts of codes being discussed and a bunch of people saying that the system needed to be charged.
    I wish the wizards who are guessing (i.e. needs a charge) would not offer their suggestions.
    If it is blowing cold, you obviously do not need a charge!
    I was thrilled when I found your write up because it made total sense.
    I just came from my garage. After reading your terrific, informative article, I did the most obvious repair.
    I located the valve, hit it about 20 times with the handle end of a heavy screwdriver and then started the car.
    While the car was running, I kept hitting the valve in order to free it up.
    Checked inside the car when it reached full operating temp and was happy to see that it no longer was blowing hot.
    I realized that it was not blowing as cold as the passenger side, so I can logically assume that the valve freed up most of the way, but is still letting in a little hot coolant.
    At this point, I plan on smacking this thing daily when the car is being used and if it doesn't return to normal in a few days, then I will follow your terrific explanation.
    Thanks again.
    Cool Joe in Hot Florida
     
  4. rodisi

    rodisi Senior Member

    Messages:
    184
    Likes Received:
    3
    Joined:
    Jun 30, 2011
    Location:
    Germany
    Your Mercedes:
    E220CDI 1999 W210
    Thanks PoD for the effort you've put in to explaining this duovalve business. However, you cheated, you chose a car that was nice and easy to get to the connector of the valve. :) On my E220 W210, the buggers went and put it right next to the a/c unit and almost impossible to put fingers in to get to it.

    Anyway, I noticed a couple of nights ago that one of the rotary controllers was not lit so I thought I'd have to change the bulbs. Last night, it was on but then I noticed that I could not regulate the heat, it was on all the time. I tried the a/c but that doesn't appear to be cooling so I searched and came across this very helpful thread, which I shall follow, however, I have a couple of questions before I do.

    Malcolm said
    for where to find the pump. This link doesn't exist, is there an update?

    Also is there anything that can be checked in the rotary switches? I mean can one get to the back of them to check?

    Off topic, in the attached photo, to the left of the duovalve, there appears to be a tube with an open filter at the end of it. What is it?
     

    Attached Files:

  5. television

    television Always remembered RIP

    Messages:
    164,074
    Likes Received:
    277
    Joined:
    Mar 14, 2005
    Location:
    Daventry
    Your Mercedes:
    2002 SL500, 216 CL500, all fully loaded
    Basically do you have any voltage on the center pin in the connector, it should be at 12volts. it needs 12 volts to put the valve in the cold mode, this variable voltage comes from the controller and it swings from 0 to 12volt on each outer pin dependent on the controller settings.

    The pump is 83 and this feeds to the inlet of the duo valve, this is not responsible for no cool air.

    [​IMG]

    The fuses involved here you can see in the top here
    http://www.autolib.diakom.ru/CAR/Mercedes-Benz/1997/E320/SYSTEM WIRING DIAGRAMS/6215.pdf
     
  6. rodisi

    rodisi Senior Member

    Messages:
    184
    Likes Received:
    3
    Joined:
    Jun 30, 2011
    Location:
    Germany
    Your Mercedes:
    E220CDI 1999 W210
    Thanks for that info Malcolm, I shall update when I manage to find a way to take the connector off.
     
  7. television

    television Always remembered RIP

    Messages:
    164,074
    Likes Received:
    277
    Joined:
    Mar 14, 2005
    Location:
    Daventry
    Your Mercedes:
    2002 SL500, 216 CL500, all fully loaded
    A thin meter probe will go in the top of the plug, no good in taking it off to measure as it will be in a no load condition. Use a needle with the meter probe on the needle.
     
  8. Alex Crow

    Alex Crow Senior Member

    Messages:
    10,677
    Likes Received:
    30
    Joined:
    Jul 9, 2009
    Location:
    Super Suffolk
    Your Mercedes:
    W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
    The air filter is for ingress of air to the vacuum system for the Turbocharger vanes.

    The duovalves on the W211 cars can be lifted away from their lower section, making replacement a lot easier.
    In the picture above, you can see the ends of the metal clips that hold the upper and lower section together - lever the clips outwards, and the sections should seperate.
    IIRC anyway.
     
  9. television

    television Always remembered RIP

    Messages:
    164,074
    Likes Received:
    277
    Joined:
    Mar 14, 2005
    Location:
    Daventry
    Your Mercedes:
    2002 SL500, 216 CL500, all fully loaded
    210 Alex;):D
     
  10. rodisi

    rodisi Senior Member

    Messages:
    184
    Likes Received:
    3
    Joined:
    Jun 30, 2011
    Location:
    Germany
    Your Mercedes:
    E220CDI 1999 W210
    Excellent

    I'm surprised - I don't have a turbocharger.

    My W210 may be different from others, Malcolm. I noticed the clips earlier and was wondering if that could be their purpose. I've arrowed the one on the left.

    Alex, excuse my ignorance - do you mean that the lower section is fixed on the car and the upper section is what I need to take out to work on, if necessary?
     

    Attached Files:

  11. rodisi

    rodisi Senior Member

    Messages:
    184
    Likes Received:
    3
    Joined:
    Jun 30, 2011
    Location:
    Germany
    Your Mercedes:
    E220CDI 1999 W210
    I just want to confirm that I'm measuring what I think I'm measuring (as an old lecturer used to say).

    In the drawing below, supposedly of the duovalve connector, pin 1 has 12V and supplies an amount to pins 2 and 3 dependent on the heat control setting in the car. Where my connector is located, it is extremely difficult to access pins 1 and 2 so I'm checking the voltage between pin3 and ground. This may not give me the voltage supplied to the solenoid but it should give me a variable voltage according to the control setting (if my thinking is correct.

    Now between pin 3 and ground(chassis) I'm getting 11.8V no matter where the setting is. Am I correct in assuming that there's something wrong with the rotating control?

    [​IMG]
     
  12. Alex Crow

    Alex Crow Senior Member

    Messages:
    10,677
    Likes Received:
    30
    Joined:
    Jul 9, 2009
    Location:
    Super Suffolk
    Your Mercedes:
    W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
    That is odd, a UK Mercedes CDI of any age will have a turbo on it.
    In any case, the little filter is for ingress of air to the vacuum system, and is of little consequence, and certainly not involved with the duovalve.

    The two halves of the duovalve can be split in the car, saving having to undo two or more awkward lower pipes, and having to remove the lower part of the valve from its mountings.
    The upper part of the valve has the moving parts and solenoids.
    You can clearly see it in Malcolm's picture, post #85
     
    Last edited: Feb 17, 2014
  13. shaggy

    shaggy Guest

    be careful when doing it this way without first removing the pipes
    I tried and snapped both the plungers :rolleyes: if they are weak to begin with they snap for fun!
    I then got replacements and snapped 1 of them trying to get it back on
     
  14. Alex Crow

    Alex Crow Senior Member

    Messages:
    10,677
    Likes Received:
    30
    Joined:
    Jul 9, 2009
    Location:
    Super Suffolk
    Your Mercedes:
    W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
  15. rodisi

    rodisi Senior Member

    Messages:
    184
    Likes Received:
    3
    Joined:
    Jun 30, 2011
    Location:
    Germany
    Your Mercedes:
    E220CDI 1999 W210
    Mine is a LHD German model if that makes any difference.

    So I take it you mean by unscrewing the 5 screws and not using the pins we discussed further up.

    I looked at those and have been confused even further. Some questions have arisen from those links
    1) how much coolant should I expect to pour out when I remove the hoses and open the valve?
    2) somebody commented on the fact that the coolant was green and not honey yellow - do Mercs take a special coolant?
    3) error codes where mentioned. I have noticed in the fuse box there is a big round multi-pin socket. Is that what's used for diagnostics and if so what do people use?

    I'm also worried about the voltage readings I mentioned. I don't want to fool with the valve if it's the controller.

    Again, thanks for all the help everybody.
     
  16. television

    television Always remembered RIP

    Messages:
    164,074
    Likes Received:
    277
    Joined:
    Mar 14, 2005
    Location:
    Daventry
    Your Mercedes:
    2002 SL500, 216 CL500, all fully loaded
    This shows that the control unit is not adjusting the voltage, as I said to you, there needs to be zero volts on pins 1 and 3 to get cold air.
     
  17. television

    television Always remembered RIP

    Messages:
    164,074
    Likes Received:
    277
    Joined:
    Mar 14, 2005
    Location:
    Daventry
    Your Mercedes:
    2002 SL500, 216 CL500, all fully loaded
    Why take the valve apart when the fault is not there or on it ?????
     
  18. rodisi

    rodisi Senior Member

    Messages:
    184
    Likes Received:
    3
    Joined:
    Jun 30, 2011
    Location:
    Germany
    Your Mercedes:
    E220CDI 1999 W210
    Absolutely. So now I have to go to the control unit wherever that lives. I'll do a search on control unit opening and diagnosing. Thanks.
     
  19. television

    television Always remembered RIP

    Messages:
    164,074
    Likes Received:
    277
    Joined:
    Mar 14, 2005
    Location:
    Daventry
    Your Mercedes:
    2002 SL500, 216 CL500, all fully loaded
    The wires that go to pins 1 and 3 come directly from the control unit in the car,the part where you adjust all the heating from.
     
  20. Alex Crow

    Alex Crow Senior Member

    Messages:
    10,677
    Likes Received:
    30
    Joined:
    Jul 9, 2009
    Location:
    Super Suffolk
    Your Mercedes:
    W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree

    I am sure you will find that all the LHD Mercedes W210 CDI cars have turbos as well - I am suggesting you are wrong, but hey, not important or related to the duovalve.

    How keen are you at automotive DIY?
    It seems from your questions that your are quite unfamiliar, but still keen to get involved. There are all the answers out there, but no-one can put it all on a plate for you, to understand your way (we all understand in different ways).

    You have had some very good advice here, and I suggest you continue with the electrical diagnosis side of things, as detailed above.
    If it turns out that the valve does need to be stripped, I myself would go for removing the upper half of the valve from the car, and stripping it (as per many many internet threads) on the bench.
    If you clamp the coolant hoses of, each side, very little coolant will escape.
    If you don't, a certain amount will be lost - but no-one can tell you how much.
    Mercedes cars are fine with standard coolants, nothing too special, but again it is all written on this forum and the web.

    If the valve has gone closed circuit or low resistance, the control unit will refuse to switch the earths - what did the resistance of the two solenoids measure?
     

Share This Page