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W202 C200 oil in coolant

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by Dorian, Jan 13, 2018.

  1. Dorian

    Dorian New Member

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    Your Mercedes:
    W202 C200
    Greetings, I bought used manual W202 C200 Elegance from 1995 and I am happy with the performance and comfort of the car(had E36 before).I inspected everything on the car and it is in very good shape but one thing bothers me.Upon opening the expansion tank cap,it had mayo on it,and the water was all brown with some sludge in it.I scrapped the walls of the tank with my finger and there was more of that brown sludge and mayo.Upon researching,I found it it can be a blown head gasket,but my car doesn't have all the regular symptoms. It starts up with no hiccup,either hot or cold,there is no mayo under the oil cap,it doesn't smoke,only when it is a bit colder outside,it has plenty of gas,and it idles smoothly(it also has LPG,it idles a bit rougher on it but still not very noticable),and the most important thing-cooling system is not pressurized.When I open the cap,either warm or cold,there isn't even a slight hiss.
     
  2. Taffy7hfa

    Taffy7hfa Senior Member

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    It is possible that a water way is leaking into a oil way at the head gasket, this would not necessarily pressurise the cooling system, however you would normally then expect to see signs of water in the engine oil rather than the other way round. drain and refill the coolant and see if the oil comes back.
     
  3. DREAMER NO2

    DREAMER NO2 Senior Member

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    Get a pressure test done on the coolant system.. Might be that its had a bottle of gasket seal put in there before hand ..
     
  4. OP
    Dorian

    Dorian New Member

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    Thanks for your help guys,I will flush the old fluid first and see does it start to get muddy again. I read somewhere that if you mix two types of anti-freeze,that can happen. I will also monitor the coolant level from now on to see does it go down. I checked the oil level when I brought the car 2 weeks ago,it didn't lower at all.
    Edit: Just made a small 15 minute ride,let the car cool a bit and then I checked the coolant while it was still luke warm-from brown it became green(with a few patches of brown) and the white stuff that usually was on the cap was gone,when I opened it,clear water was dropping from the cap.
     
    Last edited: Jan 13, 2018
  5. LostKiwi

    LostKiwi Senior Member

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    You can get oil in the water without water in the oil. Oil is under far more pressure than the coolant so if the leak is minimal it may seal under 15psi (coolant pressure) but not under 50 or more psi (oil pressure).
     
  6. Uncle Benz

    Uncle Benz Senior Member

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    They are quite prone to the head gasket rotting on the back corner on the exhaust manifold side. There is an oil and waterway in that corner. Often they have visible staining down the engine block from that area.
     
    daibevan likes this.
  7. Taffy7hfa

    Taffy7hfa Senior Member

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    Due to corrosion head gaskets often go between the water gallerys which are pressurized and the oil return gallerys which are not. Not sure if there is any high pressure oil passing through the head gasket on this particular engine? if you did have oil at 50 psi finding its way into the cooling system it would turn into a major problem very quickly.
     
    Last edited: Jan 14, 2018
  8. oigle

    oigle Senior Member

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    You do have a problem in that you said there was no pressure in the expansion reservoir whether hot or cold. Could be cap or could be leaking pressure elsewhere - head gasket or hose. Would expect to see coolant loss if HG or hose though.

    Ian.
     
  9. OP
    Dorian

    Dorian New Member

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    I will monitor the water and oil level in the next couple of days. I thought that when HG is blown,there must be excess pressure?
     
  10. LostKiwi

    LostKiwi Senior Member

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    The valve gear needs lubricating somehow. Camshafts and hydraulic lifters in particular require pressurised oil.
     
  11. oigle

    oigle Senior Member

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    That depends on which part of the gasket leaks. If it is from the combustion chamber to the water jacket, yes, it will over pressurise. If from water jacket to atmosphere (like around the edges), no pressurisation. In second scenario, you may see evidence of a leak if it is in a visible area - can leak around manifold or at rear of motor which you wouldn't see.
    Suggest you pressure test the coolant system and look for leaks if the pressure goes down. Pressure test your cap while you are at it.

    Ian.
     

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