Oil leak behind stator

[kellymont]

Hi everyone, (1981 MNS LH) i have a bit of an oil leak from the right hand side, (oil seal behind the stator), at first i belived it was from that plug hole at the bottom and have sealed it several times but now i think it is running down from the oil seal.
Does anyone know if it is possible to replace the seal from the outside without splitting the cases?
The manual shows that the seal is stepped into the cases making it a strip apart job, as i have just finished a top end rebuild i did not want another major job this summer, anyone any ideas??

Best Regards, Steve in England

[bikerphil]

Get a 32X45X8 seal from a bearing supplier. This seal has no lip, so the cases don't have to be split. Take off your alt cover and remove the rotor using a 16mm 1.50 pitch bolt. The old seal can be pried out using a screwdriver and pliers, side cutters, etc. You'll have to mangle it to get it out. Coat the outside lip of the new seal with some RTV, and tap it into place. Also check the press fit plug on the bottom and seal that up with RTV also. This could be the culprit in the first place.

[kellymont]

Hi, thanks for that, oil seal size is 32x45x8 in MM does this work ok only i am a bit of a purest.
Can you tell me what RTV is?
I have used Three Bond 1104 (equiv to yamabond?)
I also have used loctite 5699 that is very good.

Youre bikes look very nice, i am a yamaha nut, 1981 xs1100 Midnight Special and a 1989 RD350 power valve (RZ in the usa)

Thanks again for your help,hope we contact again.

Steve in England

[bikerphil]

Yes, that size is in MM. RTV is what we (US) call Form-A Gasket, which is a non hardening gasket sealer, silicone type but oil proof.

[trbig]

The Three Bond/ Yamabond will work well for this application.


The actual size of the seal is 7.8 instead of 8.. but you won't find a 7.8. Also, try to find a seal that has a DOUBLE lip on the inside. They seal better for longer. A normal bearing/seal shop will be a lot cheaper than a Yamaha shop for this.

The rotor can also be taken off with a three-jawed pulley puller, but the bolt is better if you have air and an impact. You probably won't find that size bolt with that thread though.. tough to find without ordering it from somewhere like Partsnmore.com or something.

Good luck.


Tod

[kellymont]

Thanks Guys, i pulled the rotor off with a flywheel extractor 3 days ago and cleaned the seal with electrical contact cleaner so it was dry, today i looked hard at it and noticed that there is a weep from the outside where it sits in the cases, not from where you would expect (between shaft and seal) that all looks dry in there.
I have looked at this seal before in the past but belived it could not be the cause of the leak or oil would run out along the shaft to the rotor causing wet shaft/rotor and inside the windings, these were always dry of oil, because the oil always ends up around the bottom plug i was sure that was the problem?
I have taken the sizes from the seal:- 32 x 45 x 6.5 - L and there is an arrow showing correct direction of shaft anti-clockwise, this may not be the original or correct size because it sits back low in the cases about 1mm.

Thanks again, Steve in England

[fredintoon]

Hi Steve,
in case you were wondering, RTV = Room Temperature Vulcanizing
so any cold-set sealing compound will work for you.

[Steptoe]

rotor removal

here,s a tip---if you don,t have any way of removing the rotor ,I can,t remember which axle, front or back ,,,wind in until tight then give it a tap, it normally pops off

[b.walker5]

... RTV is what we (US) call Form-A Gasket, which is a non hardening gasket sealer, silicone type but oil proof.

Don't forget there are many types of RTV's out there and not all are suitable for Automotive use. For example I wouldnt use a neutral cure glass sealant in a high temp application, nor would I use an acid cure RTV as a glass sealant in a fish tank. Plumbers Gutter Sealant RTV can't take much over 100 degrees C. Just be sure you are using an RTV that is suitable for your application, and if using it as a gasket be very careful that you don't use too much. It's not oil soluble and will block galleries and screens if excess gets where it shouldnt be. I've lost one engine to it and will never use it again in that application. Three Bond is the way to go.

[trbig]

i looked hard at it and noticed that there is a weep from the outside where it sits in the cases,

Not understanding what you're saying here.. but I will agree with you that a leaking seal will sling oil onto the stator generally, but if it's leaking between the CASE and the seal, it may not. BUT..that seal leaking around the crank is the usual suspect, not around it and the case. Have I confused you yet? lol.

Anyway.. a better explanation of where you saw the leak.. or possibly a pic even would be better. If that's what you're talking about and it is leaking at the seal.. but around the outside of it and not around the crank.. your best bet is to just replace it while you're right there anyway. As stated, some Three bond around the outside edge and tap it in.


Tod

[kellymont]

Yes, it looks very much like the oil is coming from around the OD of the seal and running down so it is not in contact with the shaft, it only happens when the engine has been running and it is a small amount.
I will get another seal and use three bond on the outer edge where it sits in the cases.

Thanks for all your help Guys