Ariel VB - a persistent oil leak

[SteveShone]

Hello, folks. I am the current owner (custodian) of the 260,000 miles Sam Larkman VB. Since I've owned it it has persistently, and irritatingly sprayed oil out from the offside of the engine which smothers the gearbox and surroundings with a smear of oil and attracts all the dust/muck thrown up off the road.
Whislt I have been at a loss to identify the source of the the leak, as I believe was the chap that restored the bike owning to the presence of a neatly made oil deflector under the timing case, I believe I may now have come close.
I have already replaced the oil supply and return pipes along with the pump unions to no avail. There is no loss from the breathers at the rear of the timing case.
In frustration I have this afternoon begun removing the outer timing case and chain and see that there is a space around the magneto armature shaft that looks as though it should have some sort of seal in it. It appears to have a thin steel hoop or 'top hat' inside the timing case opening but nothing else - it has been smeared around with red hermatite which does nothing to stem the flow. I believe that the oil must be escaping between the timing case and magneto - would I be correct in this assumption?
I see on the parts list that there is reference to an armature oil seal - either rubber 2080-53 or an earlier type composite one 2091-38. Am I correct in thinking that this should fit in the 'well' between the case and the face of the mag and could solve the problem?
Of course the next issue is removal of the magneto itself - I have accessed the two bolts under the drive end of the mag but so far haven't found my way into the remainder. Do I need to remove the primary cases to do that?
I've attached pictures of the timing case and also of the back side of the mag sprocket - it it the right one? I can't help thinking it should have a parallel boss to run inside a seal should there be one.

Thanks in anticipation. Steve

[simon.holyfield]

The seal that's used in that location is a thick felt washer - it's probably 1 3/4" or so in diameter and maybe 1/4" thick. You push the magneto against the case, trapping the felt in place and sealing the hole. Works fine in my experience.

[SteveShone]

Thanks, Simon. So it's big enough to cover the hole from the back of the timing case as opposed to sitting inside that recess with the sprocket running inside it?

Steve

[Roger Gwynn]

There are 3 versions of that seal, felt with steel support ring, wide rubber one without steel support and a narrow one in rubber with the support again. The intermediate one is the one currently available, a bit RTV will help hold it in place and should fix the leak, or at least reduce it. https://draganfly.co.uk/shop/59704/arma ... 2/#2090-53 "replaces all other types"

There should be 3 bolts holding mag to engine plate, all accessed from the right side, originally 3/8 Whit thread using 5/16 Whit spanner or socket. They are awkward, especially the innermost one and these are frequently replaced by UNC versions that use a smaller socket and often owners will cut screw slots cut into them. I usually remove the footrest and oil pipes to make life easier.

[SteveShone]

Thanks, Roger - order now placed (with a couple of spares in case needed for the other Ariel ).
Reassuring to know that I dont need to take the primary side off. I'll see if I can get the operating table a bit higher to reveal bolt number three!

Thanks for the prompt replies, chaps.

Steve

[Vincent.vanGinneke]

Hello Steve,
my solution :
The NBR O ring is thicker then the alloy carrier.
I've made it this large in diameter to reach over the usual damages on the front of the magdyno lid.

last pic is before I trimmed the inside to get as much space for the rear of the sprocket. (see note on drawing)

[SteveShone]

Now that's impressive and food for thought. Thanks.

Steve

[MarkO]

deleted

[MarkO]

Steve

Having just removed the mag from my VB, I can certainly confirm the presence of a seal twixt mag. and inner timing case, Mine was a thick 1/4" or thereabouts all rubber thing - I assume the wide rubber one as Roger suggests below. I would also certainly recommend a smear of RTV on the faces and on bore of the seal perhaps to aid sealing.

As for the mag., there were indeed 3 screws through the engine plate which engage with threads in the mag body - plus I had another one further inboard twixt two plates which was a swine to get at. A word of warning here - the mag is rubbish metal so go easy when tightening up. I rounded one of mine which I have bodged with thread tape! Suggest using spring washers here also.

Also take care not to over-tighten the timing chain. When you nip the mag fixing bolts up, it tends to tighten up the chain - so allow for that, and at the same time ensure the mag is pressed against the seal. Personally I grease up the chain with HD grease. I hate chains which are not well lubed.

Whilst you are there check out the timing cases' mating faces and the gasket. A smear of Permatex if the gasket is sound would not go amiss.

Obviously retime the points and make sure they don't move relative to the sprocket when tightening the taper nut up - mind it is a VB so who cares !

[Julian Murphy]

I replaced the hex bolts with cap heads underneath the platform.

Then cut the short side off a long series allen key, then with the long side, a 3/8 drive socket, extension bar and ratchet below the level of the frame rail, it was much, much easier to access and loosen/tighten the 3 fixings.