Help Installing Magneto Engine Crank Rubber Seal

[birdmannn101]

Since the last seal I replaced leaked, I am asking for any helpful tips on getting this seal to EASILY fit back into the engine.

I pulled out the leaking seal and found some metal in the engine seal area had some grooves which were made when I used a screw to pull the seal out. Should have been more careful.

I though I was going to kiss this engine good-bye, then I got out some J-B Weld and sealed up the grooves in the hole. Now all I have to do is tape the bearings so as not to get any metal in them and use a dremal to even out the J-B Weld. Then I am back to putting in a new seal.

I remember how tight it was to fit the last seal so I am thinking of heating the engine and seal up with a hot gun first. The last time I used a socket and hammered it in to the engine with a rubber hammer. Since that didn't work I am really open to any suggestions from the group on an easier way to install the seal........ Dan

 

[Al.Fisherman]

I remember how tight it was to fit the last seal so I am thinking of heating the engine and seal up with a hot gun first. The last time I used a socket and hammered it in to the engine with a rubber hammer. Since that didn't work I am really open to any suggestions from the group on an easier way to install the seal........ Dan

What is the size of the seal..A seal shouldn't be that tight that you can't tap it in as described...at least I've never had a seal that can't be installed that way.

Crankshaft... 14.8 X 27 X 3.8 (this can be thicker)
Clutch seal... 15 X 35 X 7

 

[2door]

As Al said, the seal should just tap in place. Use a deep socket that just fits inside the seal bore in the case, lubricate the crank and seal lip with oil and make sure you have the seal going in square to the case before tapping the socket with a small hammer. Lubricating the seal and crankshaft is important. It helps prevent seal damage because it won't be a dry contact between the metal and rubber before the engine oil can get to it.

Next time, don't pry a seal out from its outside edge. Use a sharp tool that will fit under the rubber lip and pry it out. Seldom are shaft seals pressed in so tight that they can't be removed this way.
Good luck. Let us know how you do.
Tom

 

[Al.Fisherman]

For the clutch shaft seal I use a 3/4" 1/2" drive Craftsman socket.
For the crankshaft seal I use a 1-1/16" 1/2" drive Craftsman socket.
Both are shallow well sockets, I insert a extension into the socket opposite the way it is used..from the socket itself. Like 2door said lube the seal both inside and outside contact surfaces.

 

[birdmannn101]

Thanks Ron for the socket sizes and Tom for information on lubing the seal first. When I replaced the first seal I lubed it but when I tapped it in the hole in the engine it kind of mushroomed and I guess that made it not seal correctly.

The idea of using a deep socket that fits in the hole should keep the seal from mushrooming when tapped it.

Thanks again for all your help....Dan

 

[biknut]

In effort to install the seal perfectly flat, I use a big washer against the seal, and then tap it into place with a deep socket. When the washer is flat against the case, the seal will be perfectly flat with the edge of the case.

This method requires less skill than just using a deep socket alone.

 

[Al.Fisherman]

Thanks Ron for the socket sizes and Tom for information on lubing the seal first. When I replaced the first seal I lubed it but when I tapped it in the hole in the engine it kind of mushroomed and I guess that made it not seal correctly.

The idea of using a deep socket that fits in the hole should keep the seal from mushrooming when tapped it.

Thanks again for all your help....Dan

Never answered my question...what are the measurements of the seal?

 

[biknut]

In effort to install the seal perfectly flat, I use a big washer against the seal, and then tap it into place with a deep socket. When the washer is flat against the case, the seal will be perfectly flat with the edge of the case.

This method requires less skill than just using a deep socket alone.

Something I always have to take into account when I'm the one hammering lol.

 

[birdmannn101]

Never answered my question...what are the measurements of the seal?

Ron,

Here is the seal that I bought from Gas Bikes http://www.gasbike.net/bike-motor-part-seal-loop.html

 

[birdmannn101]

In effort to install the seal perfectly flat, I use a big washer against the seal, and then tap it into place with a deep socket. When the washer is flat against the case, the seal will be perfectly flat with the edge of the case.

This method requires less skill than just using a deep socket alone.

Great idea BIKNUT,

Thanks....Dan

 

[birdmannn101]

Well the new seal lasted for 3 rides and blew. Guess I'll just start working on my next 4 stroke bike.....Dan

 

[2door]

How much end play do you have in the crankshaft? It's possible that the magneto rotor (magnet) is rubbing the seal and friction heat is burning it. Also this can happen if the seal isn't pressed completely into the bore. If it protrudes even slightly above the rim of the seal bore the rotor can rub it.
If it was lubricated during installation and it was driven in flush and straight you shouldn't be experiencing seal failures this quick.
Tom

 

[birdmannn101]

Hi Tom,

I don't have any play in the crankshaft. I don't believe that the magnet is rubbing on the seal. There is no black rubber marks on the back of the magnet. I pressed the seal into the engine all the way thanks to you guys. I lubricated the seal when I installed it.

Dan

 

[Al.Fisherman]

Well the new seal lasted for 3 rides and blew. Guess I'll just start working on my next 4 stroke bike.....Dan

1) Where did it blow out, around the shaft. Was the spring inserted into the seal.
2) Check your compression (bad or weak rings), you may have excessive blow by into the case.
3) I can't believe that there is too much case pressure to cause the seal to blow, but strange things happen.

 

[biknut]

It's about a 100% chance knocked the spring off the seal when you installed the seal in the case. It's a very easy thing to do.

You might consider buying a horse.

 

[birdmannn101]

Well after looking at the seal I see it is not flush with the engine and that is probably why it is leaking. I placed it flush with the engine case when I put it in. The spring is still on it.

 

[Al.Fisherman]

Well after looking at the seal I see it is not flush with the engine and that is probably why it is leaking. I placed it flush with the engine case when I put it in. The spring is still on it.

I have on occasion when installing a seal that I would have to use a sealer around the seal and engine case. A sealer like Indian Head may be needed to seal the engine case and seal. Not much you can do around the shaft. One such application was on a small block Chevy front crankshaft seal. This was on a timing chain cover. Once sealed I never had any problems.

 

[2door]

I have on occasion when installing a seal that I would have to use a sealer around the seal and engine case. A sealer like Indian Head may be needed to seal the engine case and seal. Not much you can do around the shaft. One such application was on a small block Chevy front crankshaft seal. This was on a timing chain cover. Once sealed I never had any problems.

I concure. I too have had seals that leaked around the outside circumference for one reason or another. Possibly a scratch or damaged bore surface or a seal bore that was not concentric. These were not on bike engines but other shaft seal applications. Take Als advice and if/when you replace the seal apply a gasoline resistant sealer to the outside of the seal or the bore. Just don't over do it and allow the sealer to get onto the shaft or seal lip area.

While you're in there you might want to closely inspect the crankshaft where the seal lip rides for any imperfections, rough places, scratches that might be eating into the seal.

You said that you installed the seal flush with the bore but now it was raised above it. Adding a sealer to the outside ring might act as an adhesive to keep the seal in place if the seal bore is slightly oversized allowing the seal to lift out and contact the magneto rotor.
Good luck and please keep us informed of your findings.
Tom

 

[birdmannn101]

Problem solved. An Aviation mechanic lent me his seal press to put the seal in and then I used MEK to clean the area good. Then put a light coat Aviation Form A Gasket Sealant over the seal....No Leaks

 

[wan37]

I had a seal bad on a motor that was brand new and I had a friend who had a extra seal I think it was a china one so I used some grease around the outer part and the inner part.I pushed it in and it went pretty far and it's not flush is that to far in.I started it up and still revving higher than I like.I wonder if it is still leaking air don't see any fuel mixture coming out like before.I would like to know how to test it.I can spray something around it but it idles so high I'm kinda afraid to keep it running,but it's not running all way open I can rev it higher with throttle.So should I chance and let it run so I can spray something around it?