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Generator head bolt torque

Discussion in 'Ask All Sailors' started by capta, Mar 19, 2017. Add this thread to a FAQ

  1. capta

    capta

    Joined Jun 4, 2009
    1,973 posts, 315 likes
    Pearson 530
    XX Sailing in the Windward or Leeward Islands where ever we are anchored
    Once again we are in lovely Bequia with all it's charms and it's terrible internet. Not that a good internet connection would help me on this, as I am a terrible failure at internet searching.
    Our old (no PC boards) Onan MDKD 8 kilowatt generator needs the thermostat housing replaced and to do so requires that we remove the head. Unbelievably, we actually have the parts we need aboard, but I have not been able to find the torque and tightening order for the head bolts.
    This is supposedly a 3 cylinder inline Kubota tractor engine. I have even emailed several Kubota dealers in the US requesting this information (and the Kubota model number for this engine) but have received no replies. Cummins/Onan also will not help. I have the generator end manual, the parts manuals but cannot find a shop manual on the engine itself, online.
    Should any of you good people have the time and inclination to help, it would be much appreciated.
    Thank you in advance.
     


  2. Brian S

    Brian S

    Joined Nov 9, 2012
    2,281 posts, 131 likes
    Oday 192
    US Lake Nockamixon


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  3. Sandy Stone

    Sandy Stone

    Joined Jun 2, 2007
    298 posts, 13 likes
    Beneteau First 375
    US Slidell, LA
    If you Google "bolt size and torque" you will see a chart giving you torque values appropriate to the head bolt size and type. Tightening sequence is almost always from the center out, alternating sides (ends) as you go.
    Edit: typing too slow again.
     


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  4. capta

    capta

    Joined Jun 4, 2009
    1,973 posts, 315 likes
    Pearson 530
    XX Sailing in the Windward or Leeward Islands where ever we are anchored
    Wow. I really have to thank you.
    I'd love to know the model number as Kubota parts are a fraction of Cumins/Onan, but as I said the Kubota dealers would not reply to my requests.
     


  5. Gunni

    Gunni

    Joined Mar 16, 2010
    4,359 posts, 569 likes
    Beneteau 411 Oceanis
    US Annapolis
    Cap; Believe your engine is a Kubota D950 3 cylinder.
     


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  6. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    215 posts, 40 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    My Universal 5411 still had the Kubota model # on the dipstick.
     


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  7. capta

    capta

    Joined Jun 4, 2009
    1,973 posts, 315 likes
    Pearson 530
    XX Sailing in the Windward or Leeward Islands where ever we are anchored
    Thank you all. Cummins/Onan will not even supply the engine specs. Their generator is governed to 1800 RPM's so the hp ratings aren't even the same. All this really helps, a lot.
    Number on the dipstick is, 1F 15377-364121E (great thought Michael, thanks) so perhaps I can reverse look it up as a Kubota part number?
    Thanks, Gunni, that might just solve all my problems. Anyone think a head gasket would be a good part to order to check this out? Any better thoughts?
    Now all we need is a Kubota parts supplier who will send parts overseas!
    Great guys, thank you very much all.
     


  8. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    215 posts, 40 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    My 5411 had the model # (Z500) . Unfortunately Kubota made a number of 3 cylinder engines which will make it harder for you. Universal used the Kubota 3 cylinder engine as well. Not sure which model. I was able to download a shop manual for my 5411 from Universal. Worth a shot to look if you don't get any joy elsewhere.
     


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  9. capta

    capta

    Joined Jun 4, 2009
    1,973 posts, 315 likes
    Pearson 530
    XX Sailing in the Windward or Leeward Islands where ever we are anchored
    I looked and couldn't tell. I'd need to see some pics, because the two blocks are different around the governor. But thanks. Will download when internet allows.
     


  10. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    215 posts, 40 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    If you have a good Vernier on board measuring the bore and stroke should narrow it down.
     


  11. jibes138

    jibes138

    Joined Jan 27, 2008
    2,713 posts, 79 likes
    ODay 35
    US Beaufort, NC
    Capta, I have a Universal engine overhaul manual. For the M18, M25, M25XP, and M35 the head bolt torque is 47.7 to 51.4 ft.-lbs. on all of these models. It says to apply 50% of the torque to all of the bolts then fully tighten to spec. It also says to apply oil to the bolt when installing. From what I saw on Stu's website the M25 is a Kubota D-850 and the M25XP is D-950. So either block the torque is the same. Good luck with your repair.
     


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  12. capta

    capta

    Joined Jun 4, 2009
    1,973 posts, 315 likes
    Pearson 530
    XX Sailing in the Windward or Leeward Islands where ever we are anchored
    Again, thank you all for your input. This morning I felt like I was sinking in quicksand, but now I'm quite confidant that if FedEx does their job, we will have the problem solved before the next charter.
     


  13. Neil Spooner

    Neil Spooner

    Joined Oct 24, 2015
    24 posts, 1 likes
    Hunter 356
    GB uk Brightlingsea
    I suspect the Kubota engine is the same as the Yanmar 3 cyl'. You won't go far wrong using those torques.
    Neil
     


  14. msmalter

    msmalter

    Joined Feb 4, 2006
    10 posts, 1 likes
    - -
    US Webster, NY
    The thermostat housing on my M25XPB is at the top of the engine, and I am surprised that you need to remove the head to replace it. What is wrong with it: cracked casting? stripped threads on the cover mounting screws? If it is the screws, have you considered re-tapping them with the next larger size thread? I did this when the 10-24 thread on my diesel tank sending unit stripped. I retapped it with a 12-24 thread and it tightened down fine. Another option might be to through drill the bad threads and use a longer screw with a nut on the end.
     


  15. dc78212

    dc78212

    Joined Sep 24, 2013
    36 posts, 1 likes
    looking looking
    US Corpus Christi
    Had a long drawn out answer, but deleted it. Basically let's sum it up;

    1) MOST manufacturers will NEVER respond to a consumer... EVER!!! Stop waiting for an answer.

    2) Learn how to use a search engine (Google is just one of many). Most of the replies on this board came from people who searched Google for you...

    3) Purchase the full service manual for your generator, it sounds like you are off-shore full time and let's be frank, should have one onboard in that case anyway.

    Next time you may not have Internet access and it may be more serious.
     


  16. EWARREN

    EWARREN

    Joined Sep 26, 2008
    7 posts, 0 likes
    Beneteau 351
    US Pensacola
    Contacted a Kubota dealer once to inquire as to the tappet setting. Was willing to sell me the engine manual but would not provide me the settings.
     


  17. Gunni

    Gunni

    Joined Mar 16, 2010
    4,359 posts, 569 likes
    Beneteau 411 Oceanis
    US Annapolis
    Kubota Tractor Model Kubota Engine Model
    B20TLB D950-DT
    Engine Model: D950-DT Head Bolt Torque: 48
    Tractor Model: B20TLB Main Bearing Case Bolt 1 Torque: 18
    # of Cylinders: 3 Main Bearing Case Bolt 2 Torque: 26
    Displacement (CC): 927 Rod Bolt Torque: 23
    Displacement (Cu In): 56.6 Flywheel Bolt Torque: 44
    Bore (MM): 75 Rocker Arm Bolt Torque: 15
    Bore (In): 2.9 Compression (PSI) Standard: 450
    Stroke (MM): 70 Compression Lower Limit: 325
    Stroke (In): 2.7
    Engine HP (Net): 20
    Valve Clearance (Cold): 0.008
    Piston Ring End Gap (RV): 0.017
    Piston Ring End Gap (AL): 0.035
    Main Crank Journal (Front): 1.7297
    Main Crank Journal (Center): 1.7297
    Main Crank Journal (Rear): 1.7297
    Rod Journals (Standard): 1.4553
    Crankshaft End Play: 0.012
    Front Pulley Nut Torque: 116
    Cylinder Liner ID (RV): 2.953
    Cylinder Liner ID (AL): 2.959
    Piston Diameter: 2.95
    Dimensions are inches. Torques are foot pounds.
     


  18. captrice

    captrice

    Joined Nov 26, 2012
    2 posts, 0 likes
    irwin citation 39 39
    US Panama City, Fl
    I have owned 4 MDKD 8kw Oman generators
    and all the thermostat housings were on the top front end of the generator. I would double check the location of the thermostat and not pull the head off unless absolutely necessary.
     


  19. capta

    capta

    Joined Jun 4, 2009
    1,973 posts, 315 likes
    Pearson 530
    XX Sailing in the Windward or Leeward Islands where ever we are anchored
    Gee, thanks for the advice.
     


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  20. capta

    capta

    Joined Jun 4, 2009
    1,973 posts, 315 likes
    Pearson 530
    XX Sailing in the Windward or Leeward Islands where ever we are anchored
    Th
    The gear case cover and fresh water pump are outside of the thermostat housing. I can't reach the inner bolts behind the water pump and it's attachment point is part of the gear case cover. It's either remove the gear casing cover, crankshaft pulley el al or pull the head. Pulling the head is by far the lesser of the two evils. At least that's what I've gleaned from inspecting it and the parts manual.
    If I've missed something, I'd love to hear how you did this job w/o removing either the head or gear case cover. I'd love an engine shop manual if you have one; I've had zero luck finding one, at any price, over the last 9 years. All I've found are the parts and generator end/electrics manuals.
     



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