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Airlock in the system - Mercedes ML 270 cdi Auto W163 2002

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by 13enzy, Dec 6, 2017.

  1. 13enzy

    13enzy Senior Member

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    Hi
    I have flushed out the old antifreeze and changed the thermostat in my car, what is the best way to remove the airlock in my system for the Mercedes ML 270 cdi Auto W163 2002

    The engine now heats to approximately 89 degrees.....but no hot air in the cabin
     
  2. alexanderfoti

    alexanderfoti Moderator

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    Jack the front of the car up as high as possible and run with the rad cap off and squeeze the rad hoses with a high idle.

    Did you loose much fluid changing the thermostat?
     
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  3. Frosty149

    Frosty149 Senior Member

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    He does say he flushed it;)
    But I’m with you on running it up to temp (from cold) with the cap off and squeezing the hoses, would expect a big burp or two! Ensure the heater is set to max on starting up.
    Expect to top up too.
    Good luck with it.
     
  4. LostKiwi

    LostKiwi Senior Member

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    You could also loosen the pipwork off the duo valve to allow the air to exit.
    On my Defender we did this - run the engine till warm, loosen the heater pipe at the highest point (in this case duo valve) and gently (and carefully) prise the hose in such a way that water can gently escape. The air would hiss out and a soon as water flowed just tighten the clip.
     
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  5. OP
    13enzy

    13enzy Senior Member

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    Hi
    I did exactly as you have outlined...with the heater on..... it is still blowing cold, but the engine sits nicely at 89 degrees
    the car was all right before i went into hospital, but the car being stood for over 6 weeks and when started,.....no heat.
    Flushed it couple of times with the old thermostat in (because i assumed it was stuck open and this would have let the water circulate and pour out fully at the bottom of the radiator drain plug etc). Then changed the thermostat (oh we had some fun there, as no one told me that at the bottom of the thermostat there is a hole for a rubber /metal sleeve which also connects into the engine, and when i started the engine the water was pouring out. We removed the new thermostat and found the sleeve thing lying at the side of the engine block, as it must have fallen out and we did not see it.
    any how after ripping me hair out for 10 minutes or so, the thermostat was replaced, new antifreeze added, and went through the procedure as you have outlined...... but i must mention this that i only put the heater on.....half way and after i started the car !....and only squeezed the top radiator hose ?
     
  6. OP
    13enzy

    13enzy Senior Member

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    Hi
    do you know where this duo valve would be on my mercedes ml 270 cdi auto 2002 model ????
    any photos/diagrams available anywhere ???
     
  7. alexanderfoti

    alexanderfoti Moderator

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    Its possible your duo valve is stuck then, check that the pipe that goes to it is warm. I am not sure of its locaiton on the ML but it will look like this:
    [​IMG]

    The one pipe going to it should be hot. If it is and you have no heat, try tapping on the top of the valves gently with something hard.
     
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  8. om613

    om613 Senior Member

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    My vote is a seized duo valve. They stick shut. You can dismantle and clean, if you're careful.
    T'stats don't usually fail closed.
     
  9. OP
    13enzy

    13enzy Senior Member

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    Nice picture but i cannot find this on my Mercedes ML 270 cdi Auto 2002 model......I wonder if I have one ????
     
  10. alexanderfoti

    alexanderfoti Moderator

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    Looking on EPC it looks as though your car uses flaps rather than a duo valve so that can't be the problem. Sorry!
     
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  11. OP
    13enzy

    13enzy Senior Member

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    Hi
    where are these flaps ?....... maybe I can give them a kick or something !
     
  12. OP
    13enzy

    13enzy Senior Member

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    ,and what's EPC ?
     
  13. LostKiwi

    LostKiwi Senior Member

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    Electronic parts catalog.
     
  14. LostKiwi

    LostKiwi Senior Member

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    Do you have automatic AC (with the LCD panel) or manual (with the thumbwheels for temperature)?
     
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  15. OP
    13enzy

    13enzy Senior Member

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    hi
    its the manual,with the thumbwheels for temperature control
     
  16. OP
    13enzy

    13enzy Senior Member

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    hi
    sorry a bit confusing, but to clarify, its a 'round dial' which you turn manually AND its got LED's going round it to indicate the level in increments etc.
     
  17. LostKiwi

    LostKiwi Senior Member

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  18. OP
    13enzy

    13enzy Senior Member

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    Yes thats the one
     
  19. LostKiwi

    LostKiwi Senior Member

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    Ok so that's automatic air conditioning.
    That means it will have motors driving the air blend flaps (as opposed to direct control via cables over flaps).
    It also means Star should be able to interrogate it and perhaps identify the cause.
    I'll look in EPC tomorrow and see if I can find the air blend flap motor. It'll be under the dash somewhere and likely a pig to get to...
     
  20. LostKiwi

    LostKiwi Senior Member

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    Found it in Malcolm's files:

    You'll notice from the drawing the two hoses bringing water to and from the heater matrix. These should both be warm when the engine is up to temperature. If they are the next step is to look at the blend motor and flap to check it operates correctly.
     

    Attached Files:

    Last edited: Dec 12, 2017 at 11:07 PM
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