Engine oil leak

[rosco]

Hello all Im back online after many months away ( not in prison )
On returning to the garage ,My CB400/4 has developed an oil leak which is coming from the front nearside engine mount ( I know, Bolt to long ) But is it possible to just split the lower crankcase off Without a full strip down once the engine has been removed. The old brain cells are a lot  rusty after a long lay off Please be gentle ??  Thanks

[exvalvesetdabbler]

Yes, I did that to replace the primary chain and cam chain. You will probably need some new seals that blank off the ends of the gear shafts. All the gears will stay in the top half of the engine when it's upside down. Just be careful of any loose dowels or split ring bearing retainers dropping into the works. I think the gear selector arms will need to come of before splitting.

Dave

[McCabe-Thiele (Ted)]

Are you 100% certain as to the source of the oil leak?

Very easy to find what you think are cracks in the casing that turn out to be casting marks.
Oil can easily run down from the cylinder head etc.

[Yetanotherbike]

As a youff, incredibly, despite the warning in the Haynes manual, I managed to get the bolts mixed up. The inevertable happened when I torqued the engine mounting bolts up and I heard a large cracking noise. I could see the crack adjacent to the engine mounting lug which if memeory serves me correctly is next to an oil gallery.
A mate reckoned he could weld it, however it still leaked, so I ended up getting another crankcase from a breakers yard.
I would not consider mixing crankcase halves for a millisecond. So in a worst case scenario I would prepare yourself for a full strip down.
However As McCabe-Thiele (Ted) quite rightly suggests, double check that the crack is in the casting before you assume the worst.
If the worst is the final conclusion, then you're in the right place for an answer.

[exvalvesetdabbler]

If it's on the left side, don't rule out the seal on the final drive or build up of oil thrown off the chain  that's trickling down.

I would remove the sprocket cover and give it a generous dose of gunk and then see where fresh oil emerges before pushing the panic button.

It's easier to put a thick feeler guage in when tightening these bolts and stop once the feeler guage is tight.

Regards
Dave

[Bryanj]

Cant be sprocket seal or chain oil if leak is at front

[rosco]

Hi Ted  The oil on the floor was directly under the mount I thoroughly cleaned the mount area with brake cleaner then left it  a couple of days  The oil leak was back With oil dripping from the mount area Checked around the filter housing but that dry Where the nut for the mount goes The casing looks a bit rough As though someone has had a go at it in the past  So is my number 1 suspect.  Now I know I can remove just the lower crankcase 
its better than a full engine strip.  So engine out ( Happy days ) Just need to find a good local welder around Norwich Any recommendations  I know BadFoot Customs in Yorkshire is brilliant But has a very very long waiting list
thanks for the comments

[XS850]

You could try SEAGER Engineering at Debenham, although they’re usually fully booked up as well!

[McCabe-Thiele (Ted)]

Hi Ted  The oil on the floor was directly under the mount I thoroughly cleaned the mount area with brake cleaner then left it  a couple of days  The oil leak was back With oil dripping from the mount area Checked around the filter housing but that dry Where the nut for the mount goes The casing looks a bit rough As though someone has had a go at it in the past  So is my number 1 suspect.  Now I know I can remove just the lower crankcase 
its better than a full engine strip.  So engine out ( Happy days ) Just need to find a good local welder around Norwich Any recommendations  I know BadFoot Customs in Yorkshire is brilliant But has a very very long waiting list
thanks for the comments

A bit of bad luck with the casing damage, at least it's fixable,