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Compressor belt on an OM366

Discussion in 'Generators/Gensets' started by Frankhaddad, Aug 29, 2019.

  1. Frankhaddad

    Frankhaddad Well-Known Member

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    Mercedes engine with an air compressor mounted to it, when compressor is activated, belt bounces around violently, not activated, looks okay. have a video on my phone. belts do not last long in this condition. Any ideas would be great. Compressor is true to the other pulleys.
     
  2. MarshallPowerGen

    MarshallPowerGen Well-Known Member

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    Occupation:
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    Tensioner been replaced? Is the compressor factory, or an add on? All the pulleys been checked for any bearing play or wobble?
     
  3. Frankhaddad

    Frankhaddad Well-Known Member

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    Everything is factory, This model is mounted in a Unimog large vehicle. This compressor is the only component run on this belt from the crank shaft. Adjustments are made at the compressor. Yesterday was the test after extensive work making sure everything was spot on. I have a video on my phone that I could send you. He has had a lot of pros look at it, I have 25 years experience myself, just not on Mercedes. It looks great when the compressor is off but on the belt looks like its going into a death wobble. The belt is also from the manufacturer.
     
  4. MarshallPowerGen

    MarshallPowerGen Well-Known Member

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    Yeah, I was asking generally to knock out the basics. I'm not familiar with those Mercedes engines, and especially not in Unimogs, and especially when it's an issue with a belt drive compressor in the generator section of the forum.
     
  5. Frankhaddad

    Frankhaddad Well-Known Member

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    I know right! I have a reputation of being the king of funky things up here in Maine. Everything that no one can figure out comes to me. Eventually I will prevail! But this is an odd one. Could I send a vid to your email just to get another set of eyes on it? it shows at the beginning at rest, then the compressor turns on.
     
  6. Birken Vogt

    Birken Vogt Charter Member

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    Does it smooth out when the RPM is changed? Or happen at idle only? Tried changing the idle RPM either direction?

    Old Ford diesel trucks used to have a v-belt that slapped around a good bit to the alternator. They usually ran fine like this, but occasionally would jump off, but not much you could do about it.
     
    MarshallPowerGen likes this.
  7. MarshallPowerGen

    MarshallPowerGen Well-Known Member

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    Occupation:
    Diesel & Generator Mechanic
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    I relate to that, having an '86 F350 6.9idi with the slappy alternator belt as a daily driver. You either let it do its thing, or wipe out the alternator bearings if you do ever get it tight enough to roll smooth, haha.
     
  8. Volvomad

    Volvomad Senior Member

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    Just because everything is OEM including the belt doesnt make it right . I would try a gates automitive (not industrial ) belt
     
  9. Frankhaddad

    Frankhaddad Well-Known Member

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    I thought of an aftermarket belt, customer is very meticulous, wanted more input, thank you.
     
  10. Frankhaddad

    Frankhaddad Well-Known Member

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    The belt as it turns out is a Gates belt, I was just looking at some of my pictures.
     
  11. Volvomad

    Volvomad Senior Member

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    A photo might help . Is it a single A section belt ?
     
  12. DB2

    DB2 Senior Member

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    Is there any chance it is in fact pushing the driven pulley rather than pulling it? Or am I out to lunch here lol
     
  13. hosspuller

    hosspuller Senior Member

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    A compressor has peaks & valleys of resistance. perhaps a less stiff belt would help to smooth the torque and the jumping. Another thought, lower the belt tension to let the rubber elements work.
     
  14. funwithfuel

    funwithfuel Senior Member

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    Late to the party here. Are we talking air compressor or A/C compressor.
    I remember air compressor driving off camshaft on side of engine.
     
  15. Frankhaddad

    Frankhaddad Well-Known Member

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    Air compressor belt, as soon as can figure out how, I will post pic/vid.
     
  16. Frankhaddad

    Frankhaddad Well-Known Member

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    Could not put video on, 2672 is compressor idling, 2673 is compressor engaged. IMG_2673.PNG IMG_2672.PNG
     
  17. hosspuller

    hosspuller Senior Member

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    Put a dial indicator on the compressor pulley. Bar the engine over. Looks like it's not running true by the photo blur. Do it at several places, edges, groove walls, etc.
     
  18. Frankhaddad

    Frankhaddad Well-Known Member

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    These photos are actually after I got it true. It was not before. Now it looks good until compressor starts and starts fluctuating and not sure but looks like it makes contact with the frame. I tried to load a video but wouldn't let me.
     
  19. Volvomad

    Volvomad Senior Member

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    Other than looking terrible , is the belt flapping causing problems ?
    Is it chewing up belts ?
    If it was a pulley problem I would still expect flapping when the compressor is unloaded .
    These compressors are hard to drive on 1 belt . From the pic ,the belt is loose under load due to belt stretch ,lack of tension or over loading .
    If you start the vehicle with empty air tanks ,is it as bad from the start ?
    Is it cutting out at the correct air pressure ?
     
  20. Frankhaddad

    Frankhaddad Well-Known Member

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    Customer just came back inti the picture, he had bought a new compressor to try, I installed it, made sure it was true to the crank shaft, it does get chewed up when it hits the frame, starting out with empty tanks it jumps quite a bit, tanks full, it looks perfect.