Replacing a leaking crankshaft seal

[Guest]

G'day all,

Is it possible to replace a leaking crankshaft seal (the one behind the ATU) of a '79 GS1000S in situ, ie. without hauling the motor out and splitting the cases?

Cheers,
Mike.

[tfb]

The silence is deafening... so I will reply my own thread. I thought I had nothing to lose by seeing if I could pull the old seal out -- so reached for the screwdriver plus hammer, tapped the rim of the seal inwards, grabbed it with the pliers, and hoiked it out easy as pie.
By the look of it, I think I will indeed have a crack at squeezing the new one in -- should be do-able, esp. if I use the threaded hole for the ATU bolt to pull a large socket evenly onto the new seal. May also slightly bevel the edges of the aluminium surrounding the seal, to help things get started. Some Permatex grey bond goop to help it slide in and seal should give me every reason for success. Watch this space...

[81GS850]

I don't see a reason to use any GOOP.. They make the metal part of a seal to conform to the bore, also most seals are coated with something to keep the outer part from leaking. I think all your doing is creating a bigger mess. I've never seen a seal leak from around the metal edge. Enlighten me please, ATU?

[tfb]

Thanks 81GS850. ATU = automatic timing unit, ie. the thing with the bob-weights that sits behind the timing plate on the right-hand end of the crankshaft.

[Nessism]

Several people have reported success with replacing that seal on-bike in threads here. Threads now in the archives but I'm too lazy to look them up.

[81GS850]

Thanks 81GS850. ATU = automatic timing unit, ie. the thing with the bob-weights that sits behind the timing plate on the right-hand end of the crankshaft.

Ah... You're talking about the advance weights. I've never heard it called an ATU. Is that what Suzuki calls it? Learn something new everyday. Also I wouldn't worry about beveling the aluminum so the seal slides in easier. It should be just fine.

[bwringer]

Yep, it's fairly straightforward to replace this seal.

As you mentioned, draw it in with an arrangement using a long 8mm bolt, some washers, some nuts, and a large socket or bit 'o pipe. Be creative. There's no reason to just try to bash it in with a hammer when you have a handy threaded hole right there.

Yes, the manual specifies a sealant around the outer edge. Do you DARE to defy the manual? Do ya, punk?

The one tricky bit is that the seal has to go in "backwards" so that the direction of rotation is correct. There will be a teensy tiny arrow somewhere on the seal showing the correct direction of shaft rotation. Get this right or it will leak in a few thousand miles. Guess how I learned this...

[eil]

I just did this not too long ago and it's pretty simple. Putting a bit of a bevel on the aluminum might help, when I was putting mine in I wished there was one. Just be very careful to not go overboard, there's not a lot of extra sealing area to spare.

Following the advice of a well-respected builder here (rapidray, I think?), I didn't use any case sealant, just grease. But regardless, you won't go wrong following the manual. I wasn't able to draw the seal in straight with a bolt and length of pipe so I tapped it in very gently and very evenly with a small hammer and wooden dowel. I've had a perfectly dry ignition area ever since.

[tfb]

Thanks for all that folks! Well I ended up using the old seal, combined with a large washer through which I poked an 8mm bolt, to pull the new seal in. Went *mostly* OK, but despite the bevel I put in the aluminium, and using a bit of grease, some small areas of the seal's rubber outer edge caught on the aluminium and tore as it was going in.
My solution? Just keep on winding it in and see what happens. So far all is nice and dry! Much better than all the rigmarole of splitting cases...