CB350F crankshaft oil seal leak

[royhall]

Well I was going great with the 350F rebuild.

Got the wiring together this afternoon (still needs tidying) and everything checked out and worked great first time.

Then spun the engine over on the starter with the plugs out to get oil pressure up. Got pressure fairly quick and it holds for about 8 seconds before the light comes on again, so all's good.

Then I noticed a pool of oil on the floor coming from the timing cover. On closer inspection its the timing side crankshaft oil seal that's pouring oil out. Its either a bad seal or I've put it in the wrong way around.

Anybody know if it can be changed in situ.

Got a horrible feeling the engines coming out again to split the cases.

Hope not, don't think I could face that at the moment as that's a long way in reverse.

Thanks all.


PS this was the oil seal kit I used:  http://shop.honda4.nl/catalog/product_info.php?cPath=35_93_105&products_id=734

[Orcade-Ian]

Oh heck Roy, that's a real downer.
I suppose it could be a bad seal to start with or fitted the wrong way.  After pulling all of the gubbins out from the timing side you will soon know.  Many years back I extracted a leaking, original seal using a slide hammer on self tappers around the seal.  I then fitted a new seal with a made up ring drift to carefully tap it in (a good socket might work) having first smeared the outer edge with Hylomar.  It did the trick and never leaked again.
Might be worth a try, there's only the price of 1 seal to lose.

Ian

[royhall]

Yep I'm almost certain its the wrong way round. Been checking Google pictures and its the seal with the steel backing ring. I fitted that ring to the outside of the engine, should be inside I think. O B****cks.


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[MCTID]

Nils carborundum Roy......at least you know what the problem is and how to sort it.

Have a good night's sleep and it will all look better in the morning......honest.

[royhall]

Thanks guys.

After a lifetime in engineering I put a seal in the wrong way round. "What a Muppet". I'm going to be sat in a window dribbling by the time I'm 60 at this rate.

Think I will attempt Arcadian's fix first off as another rebuild is a big price to pay for a small mistake. As long as I don't damage anything but the seal its worth a go. I may have to make a bespoke puller of some kind?

And here is the picture taken during the engine build clearly showing the offending seal in the wrong way round. I wouldn't mind too much if there wasn't a rib on the seal that fits in a slot.

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Cheers all.

[Bryanj]

That seal should have a small lip around the outer diameter on the inner edge which means you really need to split the cases, sorry for the bad news but given its not long been together I would estimate 2-3 hours to do it right

[andut]

Oh no Roy !!!!   

Such a simple thing to do when you're mind's already thinking about the next step in the build.  As MCTID says, at least you know what's wrong and how to sort it !  I hope you get lucky with replacing it in situ, but you're right - there's a flange on inner side of the seal that will probably make it difficult for the new one.  It's not too bad to get back to splitting the cases - might seem like it now given the time to get where you are, but probably not too bad as everything is already clean and new when you break it down and reassemble !

Sure it'll be running very soon !!

Andy

[mike the bike]

It's been a few years since I last rebuilt a 400 engine.  I thought there was a flange on the seal too.  That makes it a bit more tricky.  I would suggest slackening off all the crank case bolts until there's a 6mm gap then you can remove/refit without damaging the seal.
Good luck and take your time.

[Clem2112]

Case halves will need separating, cleaning up and re-sealing with fresh Yamabond (or other silicone) or it'll leak somewhere else !

[Chris400F]

What a mistake to make! But at least you have found it now rather than when the whole bike is back together.
Making some bespoke kit to replace the seal in situ might seem a clever way to do it, but it could take as long as the job
would take to do properly and even then might not work - if there is a flange on the seal it is there for a reason.
You would also know it wasn't done properly, which wouldn't be right given the time and effort you have spent on the rest of the bike.
I'd go with Mike's suggestion of slackening the crankcase bolts and try and do it that way, then reseal the cases.
Far less chance of damaging anything.

[royhall]

Yep, I can barely believe I did it myself.

Consensus appears to be the engine has to out, so that's the way I shall go.

That said, whats the easiest way of doing this. Can I take the engine out whole and get it upside down on the bench and just take off the bottom casing. Or has the whole thing got to come apart again.

Thanks for all the opinions, your right its best to do it the correct way.

Will take out all the after market seals whilst I'm in there and fit Honda Genuine. Have heard some bad reports about the after market seals, obviously after I had fitted them, so may as well kill that problem as well whilst I'm in there.

Thanks all.

[Chris400F]

Can I take the engine out whole and get it upside down on the bench and just take off the bottom casing.

Given that the engine was originally assembled upside down with the parts in the top casing I don't see why this shouldn't work.
Can't see any obvious need to dismantle everything again, just loosen the cam chain tensioner to allow for movement of the crank.

[Bryanj]

Yup, once all the gubbins is off the sides just lift the bottom case off just be carefull getting the selectors in situ on rebuild

[Tiny Tim]

Sorry to read your seal problem Roy. At least it gives me a chance to catch up.
Good luck with the fix.

[exvalvesetdabbler]

On the 400F it is possible to split the engine upside down with the top end in place. I replaced the camchain and primary chain that way some years ago. You might need to drop the cam sprocket off the camshaft though if you want the crankshaft out.  However,  if you only need the clearance to slip on a replacement seal than I would try pushing the cam chain tensioner plunger all the way back and locking it.

I made a similar slip up and got one of the blanking plugs/seal on the end of the gear shaft in wrong which blew out and dumped oil everywhere. There's a piece on the seal that locates in a recess  on the crank case. It's all too easy for it to spin round when you're playing with the gearshafts.

 

Best Regards
Dave