Crankcase oil leak

Helpful information and requests for assitance and advice
Locked
shandi
Member
Posts: 18
Joined: Tue Nov 18, 2014 11:24 am
Location: Coventry, UK

Crankcase oil leak

Post by shandi »

Hello
My '56 G9 which is now 600cc has developed an oil leak at the front of the crankcase joint. I know this has been a common problem in the past and I am in the process of stripping the engine.
The question is, do I simply replace the paper washer in the oil filter tunnel, it was ok for several years but the small weep has increased and become a nuisance.
Or do I go with the 'O' ring conversion which will mean more stripping down and machining of the groove. In this case I would appreciate any advice on 'O' ring size & type, and dimensions of the grove.

On another topic, can anyone suggest the most likely cause of the B52 gearbox whining in 3rd gear. I have tried ear plugs and a better fitting helmet but I really need to get it sorted while the gearbox is out of the frame, and before Jampot rally.

Thanks in advance
Ian :headbang:
MalcW
Member
Posts: 626
Joined: Tue Oct 24, 2017 12:05 pm
Location: DEVON UK

Re: Crankcase oil leak

Post by MalcW »

Hi, I know you've already started stripping the motor, but are you sure it wasn't leaking where the dynamo fits into the back of the timing chest? I had that and the oil made its way back along the underside of the dynamo, giving similar symptoms.
I can't help with the O ring conversion I'm afraid, I still have the paper gasket on mine, which (touch wood) is working fine.

Good luck

Malc
SPRIDDLER
Member
Posts: 8542
Joined: Wed Sep 01, 2004 1:00 am
Location: WEST SUSSEX UK

Re: Crankcase oil leak

Post by SPRIDDLER »

If it's the filter tunnel sealing there are some 'O' ring dims in this thread:

viewtopic.php?f=21&t=24962&p=208076#p208076

I believe that T & L Engineering are familiar with carrying out this mod.
'There is a tide in the affairs of men
Which taken at the flood............'
shandi
Member
Posts: 18
Joined: Tue Nov 18, 2014 11:24 am
Location: Coventry, UK

Re: Crankcase oil leak

Post by shandi »

Hi Malc
I made a temporary cover and gasket in place of the dynamo and the leak started within 10 seconds of starting the engine so I think that proved the point.

Hi Spriddler
Thanks for the link, the problem has no doubt been a thorn in the side for many years and will probably remain so.
I will try fitting a new paper gasket if I can get away with not fully dismantling the engine. If I find I have to take the whole thing apart I will consider the o ring method as I have a friend who will machine the groove on a CNC machine. I guess it will need a heat resistant o ring, something like Viton I suppose. I will get advice on that from my local supplier.

I will keep my eye on this thread in case there are more posts.

Many thanks Ian
User avatar
Duncan
Member
Posts: 2118
Joined: Thu Jul 10, 2003 1:00 am
Location: HAMPSHIRE UK

Re: Crankcase oil leak

Post by Duncan »

I have made a full face gasket in the past which works well but have moved on to threebond and the paper washer which also works and is less fiddley, clean flat gasket faces are important.
Are your throat bolts tight?
User avatar
1608
Member
Posts: 2493
Joined: Mon Oct 05, 2009 1:00 am
Location: ESSEX UK

Re: Crankcase oil leak

Post by 1608 »

I would let the engineer decide on dimensions of the 'O' ring. I would suggest you need to completely split the crankcase halves even to replace the paper gasket. I believe many gearboxes whine in third gear due to it being a generally hard worked gear, especially IF a sidecar was ever used with the box. I have been advised in the past ( as I'm sure the engineers amongst you would agree) gear pinions should ideally be replaced in pairs. I just accept third gear whine on my Burman box.
shandi
Member
Posts: 18
Joined: Tue Nov 18, 2014 11:24 am
Location: Coventry, UK

Re: Crankcase oil leak

Post by shandi »

I would like to thank all who replied to my request for help.

I finally decided to go with the o ring conversion as a mate with CNC machining capabilities was able to carry out the work, although I had to wait a couple of weeks. He machined a spare crankcase while the machine was set up so there could be one for sale. I will decide at a later date.

The bike is all back together and running, started 2nd kick once I swapped the plug leads round! There was no oil leak but had to abandon the idea of attending the Jampot on it due to surgery (on me not the bike) however I think we might just go by car.

Once again, thanks to all.

Ian :beer:
Locked