Oil leaking down thread of primary chain tensioner (plunger) 1954 A10 ?

[Stephen Foster]

Hello ,
Im struggling to make a seal from the primary chain tensioner screw .
As far as I am able to ascertain the oil appears to be finding its way down the threads .
Ought there to be a sealing washer abutting the case and another beneath the locknut please ?
Also are either rubber or neoprene etc gaskets available for the primary drive case joint please ?

Thank You in advance ,
Steve..

[Greybeard]

I've not had that issue. Is it possible that the case joint is weeping and the oil is finding its way to that screw?
The case should not have much oil in it; something like 250ml I think, but anyway, only enough to wet the chain.

A paper gasket with Hylomar works for me. I've even had success with Hylomar on only the engine side of the gasket and grease on the case side.

I did spend time making sure the mating surfaces were flat and none of the tapped holes were pulled up which can happen if the screws are over-tightened. I'm anti Allen Head screws for that reason.

[Rex]

I had the same problem, though the oil wasn't originating from the screw itself. In my case it was just dripping off the screw as the lowest point. If you take the primary case off it's possible to see that the tensioner boss screw thread top is actually above the level of the lube anyway.

[Stephen Foster]

Thank You both for the advice .
It may be from the primary joint but I still think it is coming down the thread ?
Will check later in the week .
What is the best gasket material for this face please ?

Regards,
Steve..

[Greybeard]

Thank You both for the advice .
It may be from the primary joint but I still think it is coming down the thread ?
Will check later in the week .
What is the best gasket material for this face please ?

Regards,
Steve..

I've usually just used the one from a standard gasket set. I have cut my own but I've also not used a gasket; just blue Hylomar. If used correctly it's great stuff.

With the oil filler plug out, are you feeling 'blow' from the case. If so, maybe your breather system is not functioning correctly.

[Swarfcut]

  Nothing special about that jacking screw. A new standard Whitwoth bolt will do the job if the threads are worn. Loctite or Silicone on the threads, in bad examples another nut in the case, bearing on the threaded mount under the slipper foot with a plain washer  on an O ring, (or a proper Dowty washer if you have one) are all other tricks. An inner locking nut  means the primary chain can only be adjusted with the cover off.
 
 Gasket faces need to be well prepared, bolts the right length for the holes and holes cleared of any accumulated old gasket cement, oil, and detritus that could cause the bolts to bottom in the blind holes before clamping the cover.

 Bathroom Silicone used carefully can also work well with pitted or gouged  faces. Deeper damage.... I've had success with Epoxy Putty.

 Swarfy.

[Stephen Foster]

Thank You very much "Swarfcut" .

What size is the screw please for a Dowty washer & which Loctite variety ?
I cannot source 5/16th ?

Regards,
Steve..

[Swarfcut]

   It was only a suggestion to change the jack screw if other methods failed.  5/16" BSW threaded bar is available from hardware and engineering suppliers, you could possibly obtain a genuine and unworn original part but of course this carries a premium.  Drags list 67 1268 and an earlier version 67 1265,  which I would expect to interchange, and as usual have no current stock.

    I'd try the simple stuff first, bathroom silicone or a thread lock grade of locking compound, so called Loctite blue, but any generic cyano-acrylate would do. Then a locking nut and compressed O ring if you have one.  Not worth the expense of sophisto sealing washers for just a single application, but fine if you have a choice from Grandad's box of mystery bits.

 Swarfy.

[Minto]

Still trying to get mine to seal, the primary is off at the moment so will have another go at it this week.

[Jules]

if its just leaking through the threads why not just use plumbing teflon tape??

[orabanda]

The thread will seal if you apply 569 loctite (Hydraulic sealant).
However because the casing is aluminium, it is critical you use Loctite's "Primer T" (in a green aerosol can) to prepare the aluminium.
Richard

[Stephen Foster]

The thread will seal if you apply 569 loctite (Hydraulic sealant).
However because the casing is aluminium, it is critical you use Loctite's "Primer T" (in a green aerosol can) to prepare the aluminium.
Richard

Thank You ,
I am trying to source a Dowty washer without success ,
Would You know the size required please ?

[Rex]

An ordinary fibre washer and/or PTFE would be sufficient, but as mentioned above, the top of the screw thread's boss is above the oil level in the chaincase anyway.