pp115 jet drive seals

Discussion in 'Jet Drives' started by bri70123, Sep 23, 2013.

  1. bri70123
    Joined: Sep 2013
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    Location: durham

    bri70123 Junior Member

    Hi

    I picked up some rope which wrapped around the prop shaft melting the seals. The manufaturer has gone now and all i can find in the manual is part number 115-156 or B.O 45 62 7.

    Would these be suitable (ebay)?

    400338853790
    Also are there any other parts i should be changing whilst its stripped down and out of water to improve performance.

    thanks

    charlie
     
  2. bri70123
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    bri70123 Junior Member

    Also if anyone has any idea why boat only goes 6-7 knots at 2500 RPM, used to go 4 x this. no blockages in jet, It is a taskforce 810, with 350HP. It hasnt been lifted and antifouled for a while and there are lots of mussels stuck to it, would this cause this much reduction in performance?

    thanks
     
  3. baeckmo
    Joined: Jun 2009
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    baeckmo Hydrodynamics

    For mechanical seals, one of the main suppliers is "John Crane Co". These units are produced for, and used in industrial pumps all over. Like bearings, they are standardized in dimensional steps, and the JC people will certainly be able to assist. Have the main dimensions (shaft dia, seating dia and corresponding lengths) and the old bits at hand when approaching JC. Please observee that the seal spring has to be precompressed to a specific degree; the supplier will give you the correct measure.

    I have a vague memory that there was still another seal in use; could have been a "Sealol". If so, they are still exchangeable for a JC and vice versa.

    I would check the cutless bearing in the stator housing when drydocked. Also check impeller vane leading edges for dents, and when reassembling the unit be careful to adjust the impeller axial position so that you get correct tip clearance.

    The reason for low speed may well be the increased friction from the marine growth on the bottom.

    I've said it before, and I repeat it; the PP jets were some of the best jets for work boats ever produced, and it is a shame that Vosper Thornycroft did a lousy marketing job, ending with scrapping the whole thing!
     

    Attached Files:

    Last edited: Sep 24, 2013
  4. anthony goodson
    Joined: Mar 2007
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    anthony goodson Senior Member

    Be aware the earlier model pp115 differed from this later drawing .The seals were not mechanical silicon carbide faced seals but were rubber covered lip seals ,thats possibly where your 45mm bore x 62 mm dia x7mm thickness comes from ,if that is the case .then these seals are available from any bearing supplier in the UK .Change the springs to stainless steel as used in the catering trade seals. The tailshaft bearing may be a cutlass bearing or it could be DU bushes made by glacier bearings ,again available from any bearing supplier in the Uk .Which you have will depend on the originall spec and year of your jet. If the tailshaft runs in an oil bath they are DU if not then it's cutlass ,only by looking will you know.
     
  5. bri70123
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    bri70123 Junior Member

    hi

    thanks for the replies, the manual has 1.1.86 on the top of the pages which could be a date, someone has wrote on the exploded diagram "stator now GRP, with water Lube BRG". and they have scribbled out some section:

    [​IMG]

    this is the remains of the seal, it looks deeper than 7mm - i just assumed it was the three seals melted together:

    [​IMG]

    [​IMG]

    I think it is labeled as part #156 on here:

    [​IMG]

    thanks
     
  6. anthony goodson
    Joined: Mar 2007
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    anthony goodson Senior Member

    The date is about right ,the section scribbled out is the original stator arrangement with a metal core and blades, and Du bushes as I suggested earlier .This no longer concerns you and has been crossed out because the jet has been retro fitted with a GRP stator unit containing a cutlass bearing,if this is sloppy on the shaft mic it up and order one online ,it should be a standard size. The 3 seals [no156 ] in the diagram are just Gaco lip seals ,the 5th one numbered 156 at the front should be in good enough condition to read the sizing numbers around the rim, make sure you get SS springs as these face the water .There should be a gap where grease nipple[158] channel exits inside the casing.I am of course assuming that the front bearing and sealing arrangement is as original as per the drawing. It would be as well to replace all seals and 0 rings whilst you are at it take all the bits to your local bearing stockist to match them
     
  7. baeckmo
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    baeckmo Hydrodynamics

    Beautiful, nice to see you here again, Anthony!
     
  8. anthony goodson
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    anthony goodson Senior Member

    Thankyou, baeckmo
     
  9. bri70123
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    bri70123 Junior Member

    nylon bushes

    Its all stripped down now, the nylon bushes on the bucket are badly worn, are these available "off the shelf" anywhere or do they have to be made?

    thanks

    btw after the cutlas bearing, the fibeglass cone has a hole drilled right through and there is a stainless steel sleev inserted, it this normal as it is off centre and looks messy, Is this just there to allow water through to get to the bearing

    thanks again
     

  10. anthony goodson
    Joined: Mar 2007
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    anthony goodson Senior Member

    Good morning bri

    It may be worth contacting Vospower or Naiad re the bushes ,but alternatively you may be better off sourcing some material on ebay and finding somebody with a small lathe to make you some . Dont use nylon ,it tends to absorb water and swell ,polyacetal would be better.The cutlass bearing needs a flow of water through its flutes in order to maintain lubrication ,the exact position of this bleed hole is unimportant.
     
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