Generator head bolt torque

capta

.
Jun 4, 2009
4,766
Pearson 530 Admiralty Bay, Bequia SVG
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.
 
Nov 9, 2012
2,500
Oday 192 Lake Nockamixon
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Jun 2, 2007
403
Beneteau First 375 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.
 

capta

.
Jun 4, 2009
4,766
Pearson 530 Admiralty Bay, Bequia SVG
We need the model number. This link downloads a PDF listing torque specs for lots of Kubota engines. It's a direct download link, so might take a while on spotty interwebs connections: http://kubotabooks.com/AutoIndex/index.php?dir=Engines/&file=Kubota engine specs.pdf

Found this image of head tightening order 3 cylinder: http://www.kumarbrosusa.com/kubota/images/5-series-images/Cylinder-head-tightening-order.jpg
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.
 

capta

.
Jun 4, 2009
4,766
Pearson 530 Admiralty Bay, Bequia SVG
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.
 
Jan 5, 2017
2,263
Beneteau First 38 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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capta

.
Jun 4, 2009
4,766
Pearson 530 Admiralty Bay, Bequia SVG
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.
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.
 
Jan 5, 2017
2,263
Beneteau First 38 Lyall Harbour Saturna Island
If you have a good Vernier on board measuring the bore and stroke should narrow it down.
 
Jan 27, 2008
3,045
ODay 35 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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capta

.
Jun 4, 2009
4,766
Pearson 530 Admiralty Bay, Bequia SVG
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.
 
Oct 24, 2015
32
Hunter 356 Brightlingsea
I suspect the Kubota engine is the same as the Yanmar 3 cyl'. You won't go far wrong using those torques.
Neil
 
Feb 4, 2006
16
- - Webster, NY
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.
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.
 
Sep 24, 2013
36
looking looking 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.
 
Sep 26, 2008
7
Beneteau 351 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.
 

Gunni

.
Mar 16, 2010
5,937
Beneteau 411 Oceanis 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.
 
Nov 26, 2012
2
irwin citation 39 39 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.
 

capta

.
Jun 4, 2009
4,766
Pearson 530 Admiralty Bay, Bequia SVG
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.
Gee, thanks for the advice.
 
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capta

.
Jun 4, 2009
4,766
Pearson 530 Admiralty Bay, Bequia SVG
Th
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.
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.