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  1. #1
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    850R smokes after going down a steep hill?

    Hello everyone,

    To cut a long story very short my 850 has developed a smoking habit.

    I live in a village in which I have to drive down a steep hill to get to my house, as you reach the bottom and start to accelerate you get a rather large amount of blue smoke.
    The strange part is that it doesn't smoke at any other time, fast or slow acceleration doesn't seem to make it smoke, its only after going downhill.

    Now the really frustrating thing is that in the last 3000 miles its had;

    Fully rebuilt head and new valve guides
    Piston rings
    new con-rod shells
    Headgasket
    Turbo ( the old one looked fine when we took it off )
    PCV system

    Could it be possible that something has been left out of the rocker box like a piece of gauze and the oil is getting into the inlet that way?

    I like the car buts its bit me badly once already and ive put far far too much money into this so im getting to the point of breaking it or selling it as a project if I cant fix it. Im now living in ROI for the foreseeable future and my brother has been lookin after the car for me.

    Any help or ideas would be greatly appreciated

    cheers

    Richard

  2. #2
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    mitchyboy01's Avatar
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    Quote Originally Posted by coxy View Post
    Hello everyone,

    To cut a long story very short my 850 has developed a smoking habit.

    I live in a village in which I have to drive down a steep hill to get to my house, as you reach the bottom and start to accelerate you get a rather large amount of blue smoke.
    The strange part is that it doesn't smoke at any other time, fast or slow acceleration doesn't seem to make it smoke, its only after going downhill.

    Now the really frustrating thing is that in the last 3000 miles its had;

    Fully rebuilt head and new valve guides
    Piston rings
    new con-rod shells
    Headgasket
    Turbo ( the old one looked fine when we took it off )
    PCV system

    Could it be possible that something has been left out of the rocker box like a piece of gauze and the oil is getting into the inlet that way?

    I like the car buts its bit me badly once already and ive put far far too much money into this so im getting to the point of breaking it or selling it as a project if I cant fix it. Im now living in ROI for the foreseeable future and my brother has been lookin after the car for me.

    Any help or ideas would be greatly appreciated

    cheers

    Richard
    Sounds like turbo oil seals to me. First check I would do is to warm the car up fully and let it idle for 10-15 mins and see if it begins to smoke. May be worth doing a compression test too for the sake of 20minutes work just to rule out rings. PCV could be blocked also but it looks like you have already replaced all of these parts.

    When going down hill in gear you have a lot of oil pressure but no exhaust gasses pushing on the other side of the turbo oil seal. Oil leaks into the exhaust but doesn't burn off until you accelerate again.
    Grey 855R Manual. Totally standard.

  3. #3
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    what happens if you go down the hill in neutral?
    PIC][/SIGPIC]
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    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaa

    Facebook^^^^^^^^^^^^^^^^ Old T-5 Kompressor Thread^^^^^^^^^^^^^^^ New TT-10 Kompressor Thread

  4. #4
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    Quote Originally Posted by claymore View Post
    what happens if you go down the hill in neutral?
    Does the same.

    What annoyed me most is that everything is new so the turbo was the only thing left it we thought it could be and its exactly the same with the new one on. It does not smoke at all under hard acceleration or when coming off the gas, only when its gone downhill.

    Its almost like oil somehow drips into the inlet manifold from somewhere but we havnt got a clue where from or how?

  5. #5
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    Quote Originally Posted by coxy View Post
    Hello everyone,

    To cut a long story very short my 850 has developed a smoking habit.

    I live in a village in which I have to drive down a steep hill to get to my house, as you reach the bottom and start to accelerate you get a rather large amount of blue smoke.
    The strange part is that it doesn't smoke at any other time, fast or slow acceleration doesn't seem to make it smoke, its only after going downhill.

    Now the really frustrating thing is that in the last 3000 miles its had;

    Fully rebuilt head and new valve guides
    Piston rings
    new con-rod shells
    Headgasket
    Turbo ( the old one looked fine when we took it off )
    PCV system

    Could it be possible that something has been left out of the rocker box like a piece of gauze and the oil is getting into the inlet that way?

    I like the car buts its bit me badly once already and ive put far far too much money into this so im getting to the point of breaking it or selling it as a project if I cant fix it. Im now living in ROI for the foreseeable future and my brother has been lookin after the car for me.

    Any help or ideas would be greatly appreciated

    cheers

    Richard
    When one has done as much reconditioning to the engine as you have then one has to ask ....

    Did you fit Genuine Volvo only parts?

    Were the rings the correct part number and did you measure the ring gap squarely in the bore?

    Have you done a compression check?

    Were all the valves put back in the same guides or were the guides also replaced along with new valves?

    Were all the hydraulic tappets put back in their original place?

    Did you de glaze the bores before assembly?...if you didn`t you have to run it in fairly quickly (speed) so that it will run hotter and bed in easier otherwise if you run slowly you can get a hardglaze which will not bed in and will cause oil burning!

    99% of smoking down hill on a trailing throttle is valve guide stems or valve guide seals worn...usually you can forget pistons and rings as they wear at roughly the same rate as the main bearings etc. so if they knock or rumble then you know the rings are getting worn although you have replaced all of them!

    If you believe you have assembled everything correctly with the correct tolerances then maybe just get some more miles done and get it coked up a bit...

    One thing may help you.......when i had my first mini and was learning about motors in the `60`s i decoked it and lapped all the valves in BUT being new to reconditioning i did not wash away the carborundum paste properly and it got into the valve guides and just acted like sand paper....it took about 2 days for it to smoke on a downhill trailing throttle but got pretty bad...Lol.....even i had to learn the hardway.


    Good Luck


    Mercedes C320CDI Sport Estate 3 litre V6 7 Gear Auto
    Remap 290bhp 628Nm torque @ 1600revs 45.1mpg

  6. #6
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    The head was fully rebuilt built by the engineering firm we use and new guides were installed.

    Genuine parts were not used but good quality items were and the engine was built with all the correct checks made.

  7. #7
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    If you simply laid yourself open to others for reconditioning and you are not happy with what you have then i would do a compression test and then if not satisfactory take it back to them!

    It is pretty obvious that something is wrong!


    Mercedes C320CDI Sport Estate 3 litre V6 7 Gear Auto
    Remap 290bhp 628Nm torque @ 1600revs 45.1mpg


 

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