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Thread: Caterpillar D6D Fuel pump

  1. #1
    Join Date
    Nov 2006
    Location
    South Devon. U.K.
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    355

    Thumbs up Caterpillar D6D Fuel pump

    Today I opened up the side of a D6 fuel pump because the throttle spindle was leaking.
    I was quite surprised with what I found inside.....almost half full of sediment, water, sand etc.
    Anyway I thought I could make out the remnants of 2 springs, I am guessing one is on the throttle spindle, the other is off one of the stop bottles in the bottom.

    Anyone any clues exactly on this, is it common?

    I pulled out a drain plug behind this which I think maybe drains the main housing, clean diesel ran out so I am hoping that its clean in there.

    All/any advice grately received!Caterpillar D6 fuel pump.jpg
    Richard

  2. #2
    Join Date
    Dec 2006
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    victoria australia
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    3,474

    Default Missing Timing Pin/Bolt

    Hi Richard,
    the crud gets into the normally dry detent and Idle adjust screw housing when that Chinese bloke Sum Wun steals or forgets to put back the Injection Pump Timing Pin/bolt, P/No--4N6430, back in place into the protrusion you see at the rear of the outer cover you have removed.
    When the crud and water gets in it causes rust pits in the springs and they fail/break--quite common due to the above reasons. Not all engine applications had the pin/bolt, I seem to recall.

    There is an update/repair for the main rear Governor Housing spindle bushing bore--they did not have a bushing originally-- and we had a jig and reamer to fit them at The Dealer, once done they can easily be replaced.
    I think the shaft movement, when the alloy housing wears, is too much for the seal lip to cope with--along with rusting at the lip/shaft working area.

    You now cannot just simply re-fit the spindle as there are Governor actuating parts inside the Main Gov. Hsg. that will have dropped into said housing and can only be re-instated with the housing on the bench.

    The inside of the injection pump and rear gov. housing are full of fuel at around 30 PSI when the unit is operating.

    Alas, I only have a Parts Book for a D6C and not a D6D, that shows the Sleeve Metering Pump--I cannot recall if there are any major differences in the two pumps other than maybe either/or both, if at all, the Torque Spring Group and Governor Spring.
    I guess if you do not have a Parts Book I can scan what I have if it may help at least give you an idea what is inside--seals and gaskets etc. should be same between the two units.
    Cheers,
    Eddie B.

  3. #3
    Join Date
    Nov 2006
    Location
    South Devon. U.K.
    Posts
    355

    Thumbs up

    Quote Originally Posted by edb View Post
    Hi Richard,
    the crud gets into the normally dry detent and Idle adjust screw housing when that Chinese bloke Sum Wun steals or forgets to put back the Injection Pump Timing Pin/bolt, P/No--4N6430, back in place into the protrusion you see at the rear of the outer cover you have removed.
    When the crud and water gets in it causes rust pits in the springs and they fail/break--quite common due to the above reasons. Not all engine applications had the pin/bolt, I seem to recall.

    There is an update/repair for the main rear Governor Housing spindle bushing bore--they did not have a bushing originally-- and we had a jig and reamer to fit them at The Dealer, once done they can easily be replaced.
    I think the shaft movement, when the alloy housing wears, is too much for the seal lip to cope with--along with rusting at the lip/shaft working area.

    You now cannot just simply re-fit the spindle as there are Governor actuating parts inside the Main Gov. Hsg. that will have dropped into said housing and can only be re-instated with the housing on the bench.

    The inside of the injection pump and rear gov. housing are full of fuel at around 30 PSI when the unit is operating.

    Alas, I only have a Parts Book for a D6C and not a D6D, that shows the Sleeve Metering Pump--I cannot recall if there are any major differences in the two pumps other than maybe either/or both, if at all, the Torque Spring Group and Governor Spring.
    I guess if you do not have a Parts Book I can scan what I have if it may help at least give you an idea what is inside--seals and gaskets etc. should be same between the two units.
    Cheers,
    Eddie B.
    Hi Eddie,

    Thankyou for the reply.

    The customer ordered the spindle seal and gasket and I arrived to fit it........but we were both surprised what greeted us on the other side.
    I do have a parts book but not with me at the moment and not on the job site where the machine currently is.


    I guess the post was more of a fishing expedition to see what your collective experiences were with it were.

    Many thanks once again

    Richard
    Richard

  4. #4
    Join Date
    Nov 2006
    Location
    South Devon. U.K.
    Posts
    355

    Default

    This is what the innards look like......seems i have to take that screw out to get at that bottom spring. Judging by the rust I don't think its gonna undo too easy.

    With the cover off it is surprising how the diesel seems to drip through in to this part of the casing....so I am guessing the seal behind has failed.

    Is there a procedure to remove the entire fuel pump to get it re-sealed? (setting the timing for the pump and the engine on No.1)

    I guess I need to start looking for a repair manual off ebay D6 fuel pump.jpg
    Richard

  5. #5
    Join Date
    Jan 2012
    Location
    Australia
    Posts
    14

    Default

    This might help. I have no idea what order the software has put them in.
    Attached Images Attached Images

  6. #6
    Join Date
    Jan 2012
    Location
    Australia
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    Default

    Some more....
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  7. #7
    Join Date
    Jan 2012
    Location
    Australia
    Posts
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    Default

    Last one......
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  8. #8
    Join Date
    Dec 2006
    Location
    victoria australia
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    3,474

    Default Sleeve metering In-line Injection Pump Air Bleed Point

    Hi Team,
    thanks R.C. for taking the time to put up your S/M Pics.

    The scan below shows where to bleed air from the Governor Housing after re-fitting the unit.
    This fact is not in any Cat Manuals.

    The bleed tap on top of the main housing near the big side plate gets the air out of the main body of the unit BUT, some air remains trapped in the Gov. Hsg. and so needs to be bled also-- if this is not done you have to crank the engine until fuel can compress the trapped air back into the Gov. Hsg., which levels out into both areas when the engine is stopped, up to a level high enough for the Inj. Pump plungers to pick up fuel and so start the engine.
    This issue is repeated each time the unit is started until said air is bled out.
    Cheers,
    Eddie B.
    Attached Images Attached Images

  9. #9
    Join Date
    Nov 2006
    Location
    Corralitos, Ca.
    Posts
    15,379

    Default

    You don't need to remove the entire injection pump/governor to work on the governor section.That compartment you are looking at should be dry, yes, the inboard seal has failed.
    For some strange reason the parts diagram only shows one 4N2786 seal (item 10) but there are actually two used.
    Attached Images Attached Images

  10. #10
    Join Date
    Nov 2006
    Location
    South Devon. U.K.
    Posts
    355

    Thumbs up

    A big thank-you to EdB, RC, and OM for this information.
    It is greatly appreciated!

    All the best
    Richard
    Richard

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