I have a slight leak of gear oil, but am not sure where it's coming from. Is there any chance it could be coming from anywhere on the timing (RH) side? Phil.
Of course it can leak anywhere. Usually seals. not mating surfaces, bypassing screws and even through bad castings. Are you certain that it's gearbox oil? Had a hard to find leak on my B40 from a faulty inlet oil rubber pipe. Dripping from footrest bracket.
Two of my eight British bikes don't leak. A Norton twin not finished restoring, no oil in it to leak and a Manx with a Molnar engine. Just lying, after a full race season one drop of oil from the rev counter drive.
Wife don't understand why oven trays disappear.
Pretty sure there is a slight leak of gear oil. I put some red dye in it, and I think the leak drip has that colour. Trouble is, I'm colour blind! So it's not simple. But then not much is. Phil.
Something for you to ponder as you toast your toes by the fire this evening. Sooner or later, maybe when the weather is not quite so cold, I'll revisit this. When I had a look a few weeks ago it looked like it might be coming from the bottom of the outer timing side cover. How might gear oil get into there? Phil
I'm guessing from a shaft oil seal or the inner casing joint?
Phil
Hi Phil,
On my B40, one of the many leaks was gear oil running along the threads of the lowermost Timing casing bolt. This bolt, though not apparently designated as a drain, went through both the outer and inner casings. Unfortunately a PO had graunched a metric bolt into the alloy which had subsequently stripped allowing oil to run along what was left of the threads, even though they had used half a tube of Hylomar to try to seal it.
Also had some oil running along the gearchange shaft. Think that was mainly coz there was too much oil in it.
Rebuilding the engine at the mo, helicoiling and welding as I go!
Pete
Just reading the posts again. Re the bottom of the timing cover. As you say it should be dry. I did have a recent weep from there and investigated it. There's a tiny drain hole as per photo which had become blocked either with muck or sealants over the years. It prevented the collected "waste" oil from returning. I got a small twist dril and cleared it out by hand, then I straightened a paper clip to its last joint and puggled away until there were no restrictions. The hole seemed to be 2-3" deep. Hasn't wept from the timing side since.
Hope that helps
So the oil drsins away into the crankcase. But where would it have come from to get inside the outer timing case? Phil
It appeared to be coming tracking through the clutch operating arm hole /shaft. There is nowhere else I could see plus it was moist around that area. Guess the oil gets flung on to the shaft and works its way along?
The B40 has a timed crankcase breather (next to the the cam pinion locknut) which exits into the outer timing case. This allows pressure and oil mist to enter the timing case. This is the source of the oil in the timing case and is the reason that there is a drain hole. Later B40s had a breather hole at the rear of the outer timing cover.
Is that it at top right on the above photo? Just to the right of the nut? Phil
Yes
If you look at the left hand side of the photo there is a small notch in the face of the inner timing case just below the rearmost case screw. This is the breather hole when the outer case is fitted
Very interesting - thanks very much Pete. I guess I might need to get a paper clip ready. I think I'd want to be very careful sticking a tiny drill bit in there in case it snapped below the surface. Phil
Is it necessary to check if the top right breather hole from the crankcase is clear? If so, how? Presumably there is something at the other side rather than it just being a plain hole? Phil
Hi Phil,
Don't worry about breaking the drill bit. It will only be soft goo and much causing the obstruction. I held the bit between my thumb and finger and rotated by hand to clear out the muck, bit by bit. I only used it as far as the spiral on the drill bit then swapped to the paper clip.
Make sure you keep the last 1cm of the paperclip bent at 90deg as you don't want the paperclip suddenly disappearing inside. If you had some welding rod or similar single core stiff wire, the would do. I only had a paperclip to hand.
I've yet to brave the garage (the older I get, the less I like winter!) but I think if there is an oil seepage at the bottom of my outer casing it might be, at least in part, gear oil (identified by dye, although judgement hampered by poor colour vision!) If so, then, if the drain hole is clear, some of it would drain into the sump. I guess mixing gear oil with engine oil like that wouldn't be very good. So how would gear oil get into the outer casing? I guess the only possibilities are: poor inner casing seal, faulty oil seal on shaft, or tracking along a screw thread. Is that right? Phil
I know what you mean about the lacking of appeal of tinkering in colder weather. Everything is less enjoyable.
Your logic seems pretty sound and I'm sure a small portion of oil won't hurt. It's oil after all, only "thicker" and blended in those quantities should be fine IMO.