Tach drive oil seal failure

My 77'D developed a weep/leak at the tach drive. After reading a few threads on the subject I made the special tool and tried tightening the threaded sleeve (part #4 in manuals). When this proved ineffective I ordered the seal and "O" ring from Mike's XS and replaced both. Without losing the shim I might add.

The repair appeared to be effective after several short rides and no sign of the leak. Yesterday I rode about 100 miles and when the ride was over I had oil on my right boot and a three drop puddle on the shop floor. I'm pretty sure I followed the instructions found here under "Oil leak at tach drive" to the letter. This morning I checked to make sure that part #4 and the other associated parts are tight and they are.

Bad part from Mike's or did I do something stupid?

roy

The tach drive seal is an actual seal not just an o-ring. It has a lip that has to point the right way. Toward the oil side. You may have installed it upside down.
Leo

Nope. but thanks!

roy

Hey, Roy. I'm gonna guess o-ring. Quick search shows that even though earlier and later tach drive housings look identical, there were different o-rings called-out. Maybe you got the wrong one???

Too Many, The O ring was the correct (red) color and seemed to fit well. The leak is at the junction of the cable and its retention ring which, according to what I've read, would indicate that the seal has failed. Only other thing I can think of is that perhaps the drive shaft has worn at the point where the seal rides thereby making the seal ineffective. The bike only has 6700 miles on it so that would seem unlikely. I guessing either I snagged the seal during install (I don't believe I did) or it's simply defective. If that's the case I need a new source.

roy

Okay, I'll go with the seal, then. I'm showing that it's a SO-7-13-4. Maybe it did get nicked going in...

That seal is still available from Yamaha.

YP-93104-07036-00 93104-07036-00 OIL SEAL,SO-TYPE $3.24

YP-93210-11313-00 93210-11313-00 O-RING $2.10

Confession I bought those seals and couldn't get the old one out. I swapped in a different drive adapter.

Thanks guys, I've ordered a couple more new ones from Boats.net. Hopefully they have a different source than Mike's. Thanks for the part #s.

roy

OK, I ordered a couple new tach drive seals from Boats.net using TwoMany's part number SO-7-13-14. It was immediately apparent upon inspection that the inner diameter of the new seal (which was in a plastic sleeve marked "Genuine Yamaha") is smaller by at least 1mm than the part I got from Mike's XS. The new part is now in place and I'll take the bike out today for a test run. I'd be willing to bet that this seal will not leak.

By the way, I found a tool that made quick work of removing the old seal. The cheap metal lid flipper that your local paint store gives away when you buy a gallon of paint has the perfect hooked end to reach in and pull or push the old seal out.

roy

Royboy said:

...The cheap metal lid flipper that your local paint store gives away when you buy a gallon of paint has the perfect hooked end to reach in and pull or push the old seal out.

roy

Click to expand...

Yeah, that's a cool tool. That thing crossed my mind when looking at 650Skull's instrument disassembly thread. Sharpen the edge to get under that crimp ring...

Test ride completed, no leaks! Get your tach drive seals from Boats.net not Mikes XS.

roy

After a camping trip last night and 150 miles of riding, the persistent oil stain on madness got to me. I have two possible sources of the leak in close proximity.

This is an after work is done pic.
The oil line nut was contacting the exhaust so I added a 2nd flange seal in the head and spaced the head pipe out from the frame a bit more.

I kinda thought I had done the tach seal before but changed it again using a new shop built tool. Made from a long 1/4" bolt the head is turned down to be a close fit in the shaft bushing/ sleeve (about 5/16") and turned off to be thinner. Then the shank is turned down further so the tool can be inserted from the engine end and angled letting the head end get behind the seal and drive it out. Worked a treat. I'm leery of the paint can tool method cuz you end up prying against the inner thread on the bushing/adapter.
Careful when removing the adapter that you keep a finger on the end of tach shaft so it doesn't come out with the adapter. Possibly unseating the washer that lives at the bottom of the shaft.
Used the #R05 o-ring from the "red box of metric o-rings" which fit well, replaced the seal with a genuine Yamaha 93104-07036. I looked for a while but had no luck finding a 7mm ID 13mm OD 4mm thick seal elsewhere. I'll need more cuz that was my last seal in stock. Used a bit of WS2 dry lubricant on the seal before assembly and a bit of Hylomar blue above the o-ring on the outside of the adapter shaft.

some parts out of the bins for illustration. You need to remove the side cover if you plan to look at the tach/ oil pump gear shaft. If it's out, plan on polishing the shaft where the seal rides. I've seen several shafts deeply grooved and or corroded there. Wouldn't hurt to pack bit of thick molly grease above the seal on reassembly to reduce water, dirt entrance.

All parts involved, note special 6mm bolt with BRASS washer, and steel washer that fits at bottom of shaft. You can see how beat up the old seal was on this set. Shaft has been polished with fine compound.

To reassemble; the hole in the side must be oriented before pushing in the sleeve so the bolt will insert and seat properly.
Seal is currently $4.15 at parzilla, fits many Yamahas up through 2018 models.
A ten mile ride and no visible oil, will need to give it a week or two before any victory dance. Madness turned 11,000 miles on the current odometer today, so about 13-14,000 miles under my butt. With gentle riding the last three tanks have returned above 50MPG with the camping trip tank taking 2.64 gallons at 162 miles on the ODO for 62MPG! Most all of that was varied 35 to 60 MPH