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W163 Heater Problem

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by ferrispedro, Nov 11, 2012.

  1. ferrispedro

    ferrispedro Senior Member

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    I have a problem with my ML270 heater. It seems to work well then when I go round a roundabout I lose my heat and have to build it up again. Feels to me like a big air lock somewhere in the system so how do I go about bleeding it. Diagrams and location of heater hoses would be appreciated.
     
  2. television

    television Always remembered RIP

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    Could be a flap problem, not much to the water part

    [​IMG]
     
  3. Steve@Avantgarde

    Steve@Avantgarde Forum Supporter Authorised Forum Supporter

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    I would check the coolant level to start with!!

    There does seem to be a air lock issue, if it was a flap problem then you would hear the flap motors clicking away behind the dash.
     
  4. OP
    ferrispedro

    ferrispedro Senior Member

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    Coolant level is ok I have checked that. How do you bleed the system?
     
  5. panason1c

    panason1c Senior Member

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    Normally, the ml cooling system bleeds itself without any 'outside help'. Might be an idea to check the auxiliary electric water pump is working.
     
    Last edited: Nov 11, 2012
  6. OP
    ferrispedro

    ferrispedro Senior Member

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    Thanks,where would I find that?
     
  7. panason1c

    panason1c Senior Member

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    As you look at the engine, follow the coolant pipe from the left of the plastic coolant header tank, it connects to the aux electric pump (which is to the right of the battery).

    This pump should run at the same time the engine is running and then continue running for a further 5 minutes (approx) after the 'hot' engine is turned off.
     
  8. OP
    ferrispedro

    ferrispedro Senior Member

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    How will I know if it is running,vibration or some other indicator? Thanks again. Peter.
     
  9. panason1c

    panason1c Senior Member

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    You should be able to hear it if you put your ear to it, or, if you squeeze the (soft) hose that comes from the top of it you should feel resistance as you stem the flow from the pump.........its common for them to burn out the brushes, i took mine apart and fitted new brushes (got them from a local electrical shop and filed them to fit) a fiddly job but saves a lot of money on buying a new one.
     
  10. panason1c

    panason1c Senior Member

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    Aux pump is #104....
     

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  11. OP
    ferrispedro

    ferrispedro Senior Member

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    That is brilliant, thanks. I was reading somewhere that someone found a VW Passat pump that was similar and a fraction of the cost of a MB one. Are the brushes easily removed? Also your diagrams, are they from the Russian site?
     
  12. OP
    ferrispedro

    ferrispedro Senior Member

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    Had a listen using the screwdriver stethoscope and heard nothing.Also tried pinching the top tube but no reaction so I am guessing the pump brushes have had it. A couple of years ago you recommended Solent Tools for the brushes,how did you know which ones to ask for. Peter.
     
  13. panason1c

    panason1c Senior Member

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    I cant remember the size of the brushes but you will need new brushes 'with tails' that you will need to solder to the motor contacts...... i removed the brushes from the motor and then gave the measurement details to solent over the phone and they sent new ones to me (on receipt, i cut the length to suit), the cost was about £10 i think.

    Over the 9 yrs i've owned my ml i've renewed the brushes twice now, Previously, i'd bought similar brushes from a local electrical store and filed them to fit...........the choice is yours......
     
    Last edited: Nov 12, 2012
  14. OP
    ferrispedro

    ferrispedro Senior Member

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    If I put a bit of copper pipe between the hoses could I use the car whilst I remove the pump to work on it?
     
  15. television

    television Always remembered RIP

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    Yes and no problem at all :D:D
     

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