Crankcase oil leak - easy repair?

[Drew400]

Hi all,

Just when I thought it was nearly time to start this thing for the first time in 18 month, I seem to have dislodged an oil seal!

Those of you who have followed my 'starter motor not working' thread (http://www.sohc.co.uk/index.php/topic,8030.0.html) will know that I spun it up, only to see a large pool of oil appear! It was coming from the rotor end, so I whipped off the cover to reveal the lower 'seal' had been pushed out by the oil pressure from running the starter enough to see the oil pressure light go off... a good sign, generally!

You can see from the pictures below the 'plug' sits at the bottom of the crankcase, underneath the rotor (left corner).

My question for you experts is how best to re-fit this and stop the leak. It has a new(ish) o-ring in place. Do I just push it back in (hard) or apply some sealing gunge first?

It seems to me that this is probably a one-hit wonder, as there is no obvious way of pulling it out again, other than pushing it using oil pressure within... a somewhat messy process!

Thanks again experts,

D.

[mike the bike]

Clean it up, plaster it with sealing shite and lightly hammer 🔨 it in place.  Happened to my mates 400.

[Drew400]

That would be solution too, but sometimes I learn on this forum that I should be doing such things differently.

Thanks for the affirmation Mike.

Cheers,

D.

[Bitsa (Ralph Wright - RIP)]

Never had to do that afore.The gasket and the alt cover correctly in place should be suffice but would gently tap fully in
Cheers
Bitsa

[Drew400]

Hi Bitsa,

The chap who refurbished my crankshaft bearings popped this plug out to make sure that there were no beads left in there from the blasting process. He was right to do so as there were plenty there, despite various cleanings (e.g air line). etc.

Clearly, I need to make sure it's bashed properly back into place before I fire this baby up.

The oil seeps mainly from the rubber grommet that surrounds the exiting generator cables... something else for me to renew. Oh joy.

The real joy (at this stage) is not reading you chaps telling me to remove the engine, split the crankcase and do the whole bloody rebuild thing all over again!

Cheers,

D.

[ka-ja]

Hi
   Agree with Bitsa, the alternator cover should hold the plug in place, the "O" ring is the seal, I pushed mine in with a smear of hyomar by hand-no problem---Ken

[Bitsa (Ralph Wright - RIP)]

Drew
That plug is the end of main oil gallery and yes to clear all shite out is good but putting back its not titanics rivets just place back square if you like and tap home all the covers should do the rest.As for the wire grommets clean refit with a bit of decent gasket goo and all should be ok
Best of luck
Bitsa

[mike the bike]

You could always remove the engine, split the crankcase and do the whole bloody rebuild thing all over again!

[Drew400]

Ah ha... this forum comes to the fore once again!!!

I had put the bloody thing in the wrong way so that the pointy end was inside the engine and thus not facing outward to be retained in place by the alternator cover.

I shall continue my little project at the weekend with renewed vigour (and renewed oil).

Thank you all,

D.

p.s. Mike: made me laugh out loud, ta.
p.p.s. I wonder what else I've put in the wrong way around... might not be laughing for long!

[mike the bike]

I don't know if you've got a parts book but they're handy for determining the orientation and sequence of parts.  Failing that, it's on the interweb somewhere.

[Chris400F]

If you haven't got a Parts List this place does them at a good price and quality is OK.
http://www.ebay.co.uk/itm/Honda-Parts-List-Book-CB400F-400-4-400-Four-1970s-Reproduction-of-Original-Honda-/251407786645?pt=LH_DefaultDomain_3&hash=item3a89126295

[tom400f]

Drew

As far as I can remember that plug is only held in place by the fact that the stator cover is in place. Otherwise it is at liberty to fly out under oil pressure. As a nutter teenager I decided to start my bike like that once and it flew across the garage. Turned it off quick 

[Bitsa (Ralph Wright - RIP)]

Tom
Thats how I discovered that cos had forgotton about it.On the 750 at the top there is a blanking plug too but it dont come out so easy.Bloody good that we are are like british rail we get there in the end but quicker
Cheers
Bitsa

[Drew400]

Hi all,

Yes, it was my parts catalogue (that I'd failed to check beforehand) that revealed the error of my ways, stimulated by Bitsa's comment.

Hey ho, onward, etc.

Cheers and thanks again all,

D.

[paul G]

Drew,
              Just tap it back and put the cover back on as it holds it in place.
I found this out by accident, I had the great idea of starting the engine and cleaning the rotor with some light emery cloth.
I ended up with a very large pool of oil on the floor as the plug came out.