oil leak from crankase to chaincase

[eugenius]

Thanks Limeyrob, fully agree

[CheeserBeezer]

My theory is that the bike has wet sumped. The crankcase oil seal may still be OK but this won't stop oil tracking through the oil seal sleeve and crankshaft (where there is no seal).

[eugenius]

Thanks cheeserbeezer. How can this possibility be tested?

[eugenius]

Actually I was thinking the oil might come from the loosen screws sites

[muskrat]

G'day Eugen.
More information needed.
Does your motor wet sump? Does the problem occur after sitting for a week or two on start up or after a good run? Do you get any/much oil out the engine breather? How long does it take to get the extra oil in the primary?
Oil seeping through the stripped bolt holes or as CheeserBeezer points out the sleeve will take time. If the seal is shot a lot quicker.
To test bring the primary and oil tank to the correct levels. Go for a 50-100 mile ride and observe the levels once home.

The early engines like my 51 A7 didn't have a crank seal so when (not if) it wet sumped the whole oil tank ended up in the primary.
Cheers

[Swarfcut]

 Starting at the beginning, egenie says all the oil came out with the drain screw removed....that's what I would expect. If there was more oil in there than there should be, then it's an overfill, or as proposed, engine oil entering the chaincase via missing or failed crankshaft seal, or working its way down the loose and failed threads that go into the crankcase.

 In this latter case, I would expect oil drips from the crankcase/primary case joint, and with the rear primary mounting to the frame removed, distinct movement between crankcase and primary rear cover to some degree.

  Restoring the failed threads is first step, then you can see if a real problem exists regarding oil transfer.

 Swarfy

[eugenius]

Hi all, I have removed the engine sproket nut, the chain case and the crank seal, which seems ok (I will change it nonetheless). I have an alloy sump plate with a draining screw; once removed it a few residual oil drained out. The bike stayed stopped for long due to partial engine rebuild. I believe the oil drained slowly into the chain case. I have ordered timeserts planning to try the maneuver you have suggested.  Afterwards once substituted the crank seal too, I will see. I am sorry but I do not understand well what do you mean when you talk about wet sump. Finally to test the oil breather, isn't it necessary to remove the right-sided case?  Thanks to everybody for precious help      

[berger]

You-- Genius, i would make a note of oil level in the tank , leave the sump drain plug in and see what happens while the bike is stood, don't kick it over and see what happens to the oil level and where the oil seeps out from.

[muskrat]

G'day Eugen.
Wet sumping occurs when oil in the tank works it's way into the sump. It can take weeks or just days. When the level in the crankcase reaches the crank seal or the stripped bolts it leaks into the primary.
With the alloy sump and drain bolt. After a ride there will be about 250ml of oil in the crankcase. After a ride drain the sump and put a bowel under it to see how much drains out over a day or 2.
Yes the outer timing cover comes off. Then check for any (in out) play with the breather. There should be 0
Cheers

[RogerSB]

This visual may help you follow Musky's description.

Basically, when the engine isn't running oil from the oil tank runs down the pipe under gravity and can seep through the oil pump gears if there's any wear and then makes its way to the sump. There is a ball and spring meant to prevent this in the crank case behind the timing inner cover. Others may be able to explain that better - as I've not been there.

Rog.

[eugenius]

Thanks Musky and Roger, now it is more clear to me! The picture is illustrative as well. Once again I will try your suggestion. Ciao

[eugenius]

Thanks Berger! I will follow all your suggestions and we'll see! Ciao

[limeyrob]

What puzzles me about the chain case set up is that on the whole of the bike the only wire locking is on the two bolts that hold the inner chain-case to the crank case.  I wonder does this mean they knew there was a problem or that these were not to be done up tight?  Everywhere else has a tab washer or a lock washer, only these 2 have wire.

[chaterlea25]

Hi All
Rob,
The consequences of either of those bolts falling out is more than likely the reason they are lockwired,
The fasteners with lock tabs on the nuts are usually rotating parts

John

[limeyrob]

Yes but the crank bolts are lock washers and the bolts behind the clutch are lock nuts.