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Aerated oil in gearbox

Discussion in 'Technical Discussion' started by Kafue, Apr 27, 2012.

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  1. Kafue, Apr 27, 2012
    #1
    Kafue

    Kafue Senior Member

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    New gearbox issues to solve.
    I have just repaired the port Allison Gearbox, so I was checking the starboard gearbox oil and found the oil was aerated.

    Then checked the screen/filter and the hose to see if it may be sucking in air and found metal filing behind the screen.
    After the panic had settled I had a good look at the filings. This could be wishful thinking but they may be from left over drill filings. They certainly look like it.
    Maybe the person who replaced the rear engine seal drilled the metal part of the seal to remove it and left some drill waste to get sucked into the screen? The filings look similar to the ones I carefully cleaned out of the port side when I had to use a drill to break the old seal.

    Now back to the aerated gearbox oil.
    Looking at the stbd Hydreco oil pressure pump I think it may need a rebuild. I also would like to have a spare pump on board.
    So any advice on where I can get a rebuilt Hydreco oil pressure pump?
    Thanks.

    Attached Files:

  2. sunchaserv, Apr 28, 2012
    #2
    sunchaserv

    sunchaserv Member

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    Over filled?
  3. Capt J, Apr 28, 2012
    #3
    Capt J

    Capt J Senior Member

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    I'd say overfilled is a source. Does an allison have external hoses for like a remote mounted filter or transmission cooler? Something is not right, also water can look that way at first if your transmission cooler is leaking.
  4. C4ENG, Apr 29, 2012
    #4
    C4ENG

    C4ENG Senior Member

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    I had a situation once where an engineer before me removed the suction line to the oil pump to correct something else on the gear box. He then used the wrong gasket sealant on the flanges when he reconnected the piping. It allowed the pump to suck air and caused the psi gauge to bounce like crazy when in gear. I had no idea what was happening at the moment thinking the worst. I hired outside help to help me and they found it very quickly as there first question was "did any body recently work on this gear box and if so what did they do?"
  5. Capt Ralph, Apr 29, 2012
    #5
    Capt Ralph

    Capt Ralph Senior Member

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    oil ?

    Some oil foams more than others. Is your oil fresh? Known type?
    I use the same CF-2 oil in my TD514s that I run in my 12v71's. This low foam oil is a must in 2-stroke diesels and felt it was a good choice for my TD's.
  6. Kafue, Apr 29, 2012
    #6
    Kafue

    Kafue Senior Member

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    Thanks for the responses.
    I have checked the hoses and resealed the screen/filter connection with a new gasket.
    I think it is a pump problem as the pump is showing signs of oil leaking, not a lot but it is leaking.

    The oil I use is the same as the oil in the 12V71n's, a straight 40w recommended and supplied by the local DD/MTU dealer.

    The oil and oil filter was changed about 50 hours ago. I think it is time to try another change.
  7. Capt J, Apr 29, 2012
    #7
    Capt J

    Capt J Senior Member

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    If the pump is weeping, it is most likely the source of your leak......Try cleaning the weep and putting something like permatex #2 to seal it or rtv or something similar (none of which will last) but see if the foaming goes away.
  8. Kafue, Apr 29, 2012
    #8
    Kafue

    Kafue Senior Member

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    I'll have a look at finding a local equivalent to permatex #2.
    Thanks James.
    George
  9. Capt Ralph, Apr 30, 2012
    #9
    Capt Ralph

    Capt Ralph Senior Member

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    I think the idea is; If you find it weeping at the dock or when in the ER, then it MAY draw air when under power. Any kind of a gasket sealant would work for an experiment.
    However, It's a simple gear driven pump. I would not think it would be to hard to reseal it properly. Then again, I do not understand the difficulties when your "down under".
    I'm in north Florida. Not quite the mecca of yachting, sometimes considered south Georgia (red-neck land). Ft Liquor-dale and Miami are south of me about 300 miles. I have a great DDA shop here in town and the phone works south to those other places. If I can be any assistance in ordering seals or parts, and getting them to you, let me know.
    ,Ralph
  10. Kafue, Apr 30, 2012
    #10
    Kafue

    Kafue Senior Member

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    Many thanks for the kind offer Ralph!
    Last night I found a supplier of NEW Hydreco pumps. I am thinking of ordering 2, one runs clockwise the other CCW.
    It may be okay to do a re-build on both, but they are 30 to 40 y.o pumps, so I believe I will bite the bullet and have peace of mind. Fact is, the biggest problem is removing and replacing them, so here I go!
    Have a good week.
    Regards,
    George
  11. Capt J, Apr 30, 2012
    #11
    Capt J

    Capt J Senior Member

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    Yes, it's time......put new ones and .Save the old ones......
  12. Kafue, Apr 30, 2012
    #12
    Kafue

    Kafue Senior Member

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    Thats the idea James!
    Cheers,
    G
  13. MDS, May 1, 2012
    #13
    MDS

    MDS New Member

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    The allison transmission will aerate the oil if it is low. The proper level is full while the engine is running in neutral. Be sure to check this and verify. If you are checking the oil while the engine is not running then you will be 3/4 to 1 gal low on oil.
  14. Kafue, May 1, 2012
    #14
    Kafue

    Kafue Senior Member

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    Hi MDS,
    I have checked the oil level at idle and it is on full.
    Thanks