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  Kato

  2 years ago

  Hi 

  
  

  Just a FYI for everyones comment or notice as they see fit 

  
  

  I got a slight leak on my primary drive and started wondering why 

  
  

  When you remove the Primary Drive drain plug you will note 

  - there's no O ring ????? (to create a seal) 

  - There is no torque setting when you reinstall it ????

  
  

  There's no Torque setting as the plug cannot have one ( If yoyu keep screwing it up into the Primary Case it will "fall into" the case - well it sure seems that way to me ) 

  
  

  HD factory manual says  to screw it back into the case  with 4 mm left exposed below the cover ??

  
  

  So you need some kind of sealant placed onto the thread to create a seal so the drain plug wont leak (well in my view you do and White plumbers tape it hopeless) 

  i have opted  for Permatex high performance thread seal $25-00 and withstands pressures up to 10,000 PSI etc etc  

  
  

  Anyone experienced this problem with their Primary Drives ( All primary drain plugs have a O Ring installed from 2005 onwards i think and its a MUCH better set up i think ) 

  
  

  
  

  
  

  
  

  
  

  

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  Far Canal

  2 years ago

  Well that drain plug set up looks dodgy A.F!.

  If it were my bike I would see if one of the later type plugs with o-ring (or a suitable soft metal washer) and hex fasteners will fit.
  

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  Kato

  2 years ago

  As dodgy AF as it is - thats a factory drain plug on the primary 

  
  

  Its in all HD bikes that have this engine (until the drain plug is / was updated to a O ring style) 
  

  
  

  You CANNOT just fit a O Ring to that drain plug ( its not machined to take it ) 

  
  

  The Dealerships just replace the drain plug each time the oils changed ( what that stops i will never know ) 

  
  

  
  

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  Old Fatty

  2 years ago

  I've got an 02 Fatboy with the same plug. First time I changed the primary oil it leaked like a sieve, so I pulled it out and wrapped teflon tape around it. Never had a problem since.

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  Baloffski

  2 years ago

  That's a course pitch thread on the plug, wonder if that's a factor of leaking. Anyway, no issue on 06 Fattie, as you said K changes made. Sometimes the simplest fix is the easiest, if not the answer,  old fatty's.

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  Pedro123

  2 years ago

  Have just finished servicing my 2016 model and even with the machined plug and o ring the manual says to use a thread locker on it.
  

  
  

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  beaglebasher

  2 years ago

  I have had the primary cover off three times in the past year to fix a leak. Three new gaskets at $50 odd a pop just quietly. 

  The last time I did it I used the Permatex aviation gasket maker ( as well as a new gasket ) and I was pretty sure that would fix it.

  Until last week when I noticed another oil stain on the concrete. I wont subject everyone to the foul language I used when I saw it.

  I never gave the plug a thought until Kato mentioned it. (same type of plug ) I had a few beers under my belt by the time I screwed the plug back in and filled it.

  I have gave it a good wipe and I will have a closer look to see exactly where its coming from.

  
  

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  John.R

  2 years ago

  Pretty sure those plugs are tapered thread, not regular. If it's threading all the way in and past, somethings fucked already. 

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  Kato

  2 years ago

  John R - I can assure you the drain plug is NOT a tapered thread variety

  
  

  Beagle Basher - quietly confident it wont be the P Cover gasket . Have a look directly plumb up from where its leaking and youll find its the drain plug and it leaks "along" the case as well . Cannot believe HD dont have a O ring on their drain plug i must say on this model  

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  beaglebasher

  2 years ago

  My plug is different from yours Kato. Pretty sure it would be 1/8' NPTT   ( National Pipe Thread Tapered )  Mine takes a Torque driver to remove. ( a 3/16" Allen key if you are desperate but I would avoid that)

  The original leak on mine was because the capscrews came loose on the case . When I took it off there was a noticeable  lip / ridge on the case where it would have been vibrating against the motor but I thought the new gasket should take it up but it didnt so I done the job again and filed the lip off and put it back together with a new gasket. Still fukin leaked !

  So I done the job for the third time with a new gasket and Permatex.  Looks like it might still be fukin leaking.

  I hope it is the plug cos I cant be fucked taking the case off again. 

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  Baloffski

  2 years ago

  So Kato, what do you do to rectify? Is the drain thread able to accept a later model 'o ring drain bolt', or is it recessed slightly to take the o? No machinest but there must be a reasonable simple fix. 

  As you say is fucked up design, and they beat the Japs, how long is this drain plug been in HD  models?

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  John.R

  2 years ago

  Quoting Kato on 20 Dec 2021 07:46 AM

  John R - I can assure you the drain plug is NOT a tapered thread variety

  
  

  Beagle Basher - quietly confident it wont be the P Cover gasket . Have a look directly plumb up from where its leaking and youll find its the drain plug and it leaks "along" the case as well . Cannot believe HD dont have a O ring on their drain plug i must say on this model  

  "John R - I can assure you the drain plug is NOT a tapered thread variety"

  
  

  What level of assurance?
  
  Because its 1/8th -27 NPT stock... so not sure what's going with yours for you to be sure its not a tapered thread (well, doesnt sound like its tapered anymore anyway)

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  tussuck

  2 years ago

  Quoting beaglebasher on 20 Dec 2021 06:55 AM

  I have had the primary cover off three times in the past year to fix a leak. Three new gaskets at $50 odd a pop just quietly. 

  The last time I did it I used the Permatex aviation gasket maker ( as well as a new gasket ) and I was pretty sure that would fix it.

  Until last week when I noticed another oil stain on the concrete. I wont subject everyone to the foul language I used when I saw it.

  I never gave the plug a thought until Kato mentioned it. (same type of plug ) I had a few beers under my belt by the time I screwed the plug back in and filled it.

  I have gave it a good wipe and I will have a closer look to see exactly where its coming from.

  
  

  Could also be the clutch shaft bearing support on the inner side of the primary as well.  Can be a real bastard to get to and diagnose. 

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  tussuck

  2 years ago

  Harley part number 739 or 739A Transmission Drain Plug 1/8"-27 NPT.  I have the 739 in my old bike and you should always use a sealant with them as they will always leak given half a chance.

  
  

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  Kato

  2 years ago

  Harley part number 739 or 739A Transmission Drain Plug 1/8"-27 NPT. I have the 739 in my old bike and you should always use a sealant with them as they will always leak given half a chance.

  
  

  My 03 has the 739A Transmission drain plug . Sealant is a must as you have mentioned . Some say plumbers thread tape - thats for cold water plumbing not a hot engine . Thats why i have been using Permatex High Performance Thread Seal 

  
  

  So Kato, what do you do to rectify? Is the drain thread able to accept a later model 'o ring drain bolt', or is it recessed slightly to take the o? No machinest but there must be a reasonable simple fix.

  As you say is fucked up design, and they beat the Japs, how long is this drain plug been in HD models?

  
  

  Cannot fix it other than use Permatex as stated above in my view . Drain plugs been in for years but from 06 ( as far as i know) its been changed to have a O ring on the drain plug 

  
  

  "John R - I can assure you the drain plug is NOT a tapered thread variety"

  What level of assurance?

  Because its 1/8th -27 NPT stock... so not sure what's going with yours for you to be sure its not a tapered thread (well, doesnt sound like its tapered anymore anyway)

  
  

  Its not tapered as you would be able to see that in the drain plug and it will "take up" when you screw the drain plug into the case . If you keep screwing a tapered thread into the case it will most likely crack the casing 

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  John.R

  2 years ago

  Mate, Look up what exactly PN 739A is... or what NPT is. While it might not be obvious to the naked eye because its a tiny and short thread, its tapered. If you want to get technical, the taper is just under 1.8 degrees... 

  
  

  If it wasn't tapered, that PN would be NPS, which is the straight and NOT tapered thread. 

  
  

  Why are you so adamant its not? Because you cant see it with your naked eye? Run a micrometer over a new plug and see?

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  Kato

  2 years ago

  Quoting John.R on 20 Dec 2021 10:41 PMedited: 20 Dec 2021 10:47 PM

  Mate, Look up what exactly PN 739A is... or what NPT is. While it might not be obvious to the naked eye because its a tiny and short thread, its tapered. If you want to get technical, the taper is just under 1.8 degrees... 

  
  

  If it wasn't tapered, that PN would be NPS, which is the straight and NOT tapered thread. 

  
  

  Why are you so adamant its not? Because you cant see it with your naked eye? Run a micrometer over a new plug and see?

  Nice .........real nice . 

  Ive only put this advice (and my time to assist people for the joy of assisting people) -

  You can measure all you like with a Micrometer 

  as far as i am concerned ............. bloody hell 

  
  

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  evo94

  2 years ago

  lol...not gonna change his mind John
  

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  FBUser214

  2 years ago

  Tried plumber's tape once , seemed like a good idea at the time, then I read reports of it partly dissolving in oil and petrol.

  I now use CB 7567 pipe sealant, good for sump plugs and petcocks, and it is not going to end up in oil filters , lifters, or fuel filters.
  

  
  

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  John.R

  2 years ago

  

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