Right side crank seal...

[psycoreefer]

Ok, well I've had some oil seepage from the right side alternator cover for about a month now. Figured it was the oil galley plug, but when I pulled the cover there is a film of oil around the entire inside, not just the bottom. I went ahead and replaced the o-ring on the plug but I'm wondering if it was the crank seal weeping oil due to the oil being everywhere. I know replacement and parts have been covered in other threads and I'll find em, my question is:

How worried do I need to be about that seal, do they tend to weep oil for a long time and you just have to deal with the mess, or do they tend to fail quickly and cause massive oil loss? I'm going to the cali rally next weekend, probably around 1000 miles total by the time I drive there an back, and wondering if I should stress about replacing it before I leave or if it can wait till I get back, and maybe even until winter.

[3Phase]

Make sure it's really the seal before you stress out. Take another look under the cover and sprinkle talcum powder to track down a leak.

Put the alternator cover back on so you don't shoot yourself in the eye when you blip the throttle while trying to look and see where the the oil is leaking and the gallery plug shoots out.

Ride the bike around the block, remove the alternator cover and take a look.

If it is the seal and you can get a new one with enough time before you'd have to ride then fix it. Do you have a rotor puller? You can remove the rotor without the rotor puller/bolt but it's not a lot of fun.

[Ivan]

Typically seals fail from grit getting in the crevace formed between the seal and shaft. Since its a wear created failure, its usually progressive.In this application, since the cover and rotor probably keep most of the grit out, I would definitely suspect other sources first. As said previously, talc can help. Hose it down with contact cleaner or brake and electric motor cleaner first to get rid od residual oil. Foot powder is a convient way to apply the talc since it sprays on and sticks pretty good.

Another thought. That seal is only holding oil from the outer crank bearing back. If it is leaking at the seal, there's a good chance your bearing clearance has opened up enough to allow more oil behind the seal. If the bearing goes completely out, it will tear up the seal. Just ask me, I have been there....

[psycoreefer]

Ok, I'd like to get oppinions....
When I got the rotor off it looked like someone had put some RTV around it at some point, so it may have leaked before I owned the bike.

I removed the stock seal, cleaned up the shaft and case with some carb cleaner on a rag and then lightly coated the new seal with RTV around the outside and tapped it into place. I let the bike sit overnight before riding to work the next morning.

Problem is that the new seal leaks worse the then old one, I've yet to pull it apart but I'm guessing its leaking around the shaft, given that I've got oil seepage through the crack all the way around the cover.

Anyone got any input? what did I do wrong? Can I run the motor without the rotor and cover to help figure out where its leaking, I know about the galley plug, can I hold it in by hand? How much pressure is there pushing it out?

Ivan, is there anyway to know if that bearing is the cause of the failure with out splitting the cases and replacing it? The bike doesn't make any strange noises, and I've never noticed any metal in the oil during changes....

This is what the old one looked like, I guess I forgot to take a picture of the new one after I put it in....

[Ivan]

Looking at that picture, it appears that the rotor has come in contact with the case. Does the back side of the rotor have galled aluminum or other rub marks on it? If so, then I would suggest that the thrust bearing for the crankshaft has some how gone awry and let the crankshaft slide laterally and damaging the crankcase. The silicone is probably a patch job. However, when I install a seal I usually smear a touch of silicone around the outside to make sure any small nicks in the surface of the bore are filled and won't leak. That's a lot of silicone for that though. Also, I believe that shoulder behind the taper should be just a bit proud of the seal. I will have to look at one of my engines to be sure.

[3Phase]

Can I run the motor without the rotor and cover to help figure out where its leaking

Yes but you won't like it.

A better idea would be:
Remove the alternator cover
Leave the rotor in place. You'll be able to tell if the seal is leaking or the gallery plug.
Clean up the oil. If you can't tell what's leaking do what Ivan suggested and spray on some talcum powder or corn starch
Put the alternator cover back on
Start and briefly run the bike
Remove the alternator cover and check for leaks

I know about the galley plug, can I hold it in by hand? How much pressure is there pushing it out?

Cold it'll be over 50 PSI and will depend on how thick your oil is; hot, you won't like holding the plug by hand. You might be able to hold it in by hand but when you slip the oil pressure will immediately drop to zero when the plug shoots out and hits you in the face while you're staring at the oil seal looking for leaks.

Ivan, is there anyway to know if that bearing is the cause of the failure with out splitting the cases and replacing it?

Well, I'm not Ivan but if you grab the rotor and pull up on it it shouldn't move up/down more than 0.001" -> 0.002" (main bearing clearance), in/out more than 0.002" -> 0.004" (thrust bearing side clearance). If you have a dial indicator you can use a small bottle jack or a pry bar and blocks of wood to gently lift the end of the crankshaft.

Do not jack or pry on the rotor. It will flex enough to give a false reading. If you bend the rotor it will be out of round/balance and you'll need a new rotor.

[Ivan]

Ok, I just looked at one of my engines, and the shoulder in that pic appears to look about the same as mine. The looks of the metal being galled and some little shavings of metal around there look like something is amiss.

[psycoreefer]

Yes but you won't like it.

A better idea would be:
Remove the alternator cover
Leave the rotor in place. You'll be able to tell if the seal is leaking or the gallery plug.
Clean up the oil. If you can't tell what's leaking do what Ivan suggested and spray on some talcum powder or corn starch
Put the alternator cover back on
Start and briefly run the bike
Remove the alternator cover and check for leaks



Cold it'll be over 50 PSI and will depend on how thick your oil is; hot, you won't like holding the plug by hand. You might be able to hold it in by hand but when you slip the oil pressure will immediately drop to zero when the plug shoots out and hits you in the face while you're staring at the oil seal looking for leaks.



Well, I'm not Ivan but if you grab the rotor and pull up on it it shouldn't move up/down more than 0.001" -> 0.002" (main bearing clearance), in/out more than 0.002" -> 0.004" (thrust bearing side clearance). If you have a dial indicator you can use a small bottle jack or a pry bar and blocks of wood to gently lift the end of the crankshaft.

Do not jack or pry on the rotor. It will flex enough to give a false reading. If you bend the rotor it will be out of round/balance and you'll need a new rotor.

So how hard is it to change that thrust bearing? When I had it apart I tried wiggling the rotor and could feel no noticeable movement up/down or left/right, but in and out I could feel it move... feelable (yeah thats the technical term) is likely much more then .004. Wouldn't a bad bearing make some crazy noise and engine problems?

That thrust bearing being bad might allow the rotor to touch the case, backing up Ivans observation... I did not look closely at the back of the rotor.....

[3Phase]

So how hard is it to change that thrust bearing?

You have to split the cases.

... feelable (yeah thats the technical term) is likely much more then .004. Wouldn't a bad bearing make some crazy noise and engine problems?

Push the rotor in as far as you can then try to put a feeler gauge between the rotor and the case to check the clearance. Unless there is a really large amount of movement with an accompanying "clunk" in and out and you don't have any clearance between the rotor and the case I wouldn't worry about it too much.

That thrust bearing being bad might allow the rotor to touch the case, backing up Ivans observation... I did not look closely at the back of the rotor.....

If the thrust bearing is really worn, yes, the rotor could touch the case and seal.

Since you went through 19 levels of golly-gee-whiz to remove the rotor it might have been overtightened by the PO when the globs of sealer were put on, or it might have come loose, wobbled around on the shaft and the PO just put it back on, hammered it down with a sledge and reefed down on the bolt without checking to see of the internal taper in the rotor was destroyed.

That would put it too close to the case and seal and it'd be much easier to replace a bad rotor than a bad thrust bearing!

[psycoreefer]

You have to split the cases.



Push the rotor in as far as you can then try to put a feeler gauge between the rotor and the case to check the clearance. Unless there is a really large amount of movement with an accompanying "clunk" in and out and you don't have any clearance between the rotor and the case I wouldn't worry about it too much.



If the thrust bearing is really worn, yes, the rotor could touch the case and seal.

Since you went through 19 levels of golly-gee-whiz to remove the rotor it might have been overtightened by the PO when the globs of sealer were put on, or it might have come loose, wobbled around on the shaft and the PO just put it back on, hammered it down with a sledge and reefed down on the bolt without checking to see of the internal taper in the rotor was destroyed.

That would put it too close to the case and seal and it'd be much easier to replace a bad rotor than a bad thrust bearing!

I totally agree...

I did take a quick look at the tapper and it didn't appear damaged, I wiped it out with my finger and don't remember feeling anything not-smooth, and you can see that the crank tapper looks ok in the picture. I'll try with the feeler gauges....

On another note, anyone know how much oil pressure that seal is holding back? I know there is drain hole in the bottom behind it and I was careful not to get any RTV on the "inside" of the seal to plug that up, but I'm wondering if it became plugged somehow if that would cause excess pressure to build up behind the seal and cause it to leak...also I checked SKS's website and that particular seal is only rated for about 10psi pressure difference.....?

[dbeardslee]

You've also got a galley plug in that general vicinity that's sealed with an o-ring. They're pretty notorious for leaking, and could be compounding your problem. Just something else to check while you're in there .

[Ivan]

Bad thrust bearings usually don't make a whole bunch of noise. It sounds kind of like a very light knock that comes and goes, and is usually only noticeable at idle. On these engines, with the general clackety nature of them it may not be noticeable at all. If you can feel movement, that usually isn't a good sign, but it also depends on the guy doing the checking. I always had to use a dial indicator and my mentor could feel by hand. I have never heard of a thrust bearing issue on these engines either, so chances are its all good.

This all stems from the picture that looks like something was rubbing on the protrusion that the seal is installed in. Looks can be deceiving though.

IIRC, you said you got the seals from NAPA, which I did as well, and they were a "will-fit" type of thing that didn't actually fit as well as should. They were a fractional seal that was close on the metric dimension. You may want to hit up the local industrial bearing shop and see if they can get you a proper seal. I think the ones I got were $3 a piece, but for the left side. The right side may be similar.

Also, while you still have everything apart, look closely at the surface where the lip rides. They will usually get a groove in them from the seal, and that can be OK. What is not OK is any scratches or grooves that are along the axis of the crank. For example, someone grabbed it with vice grips and then used emery cloth to smooth it over.

The seal shouldn't hold any pressure per se. The oil behind it will be from the crank bearing and what ever splashes out of there. Probably lots of volume but not a whole lot of pressure.

On last thought, it shouldn't hurt anything to run with the rotor off. You won't get any charging, and there is a possibility that the crank is drilled for oil through the bolt hole. So you might want to get a smaller bolt and put some teflon on it or other sealant and plug the hole. I don't know how the galley plug is held in, but i have heard of them popping out, which I think was mentioned in this thread. However, I have ridden mine several miles with the ignition side cover off, while trying to adjust the vacuum pod and had no problems. So, you might just unplug the regulator and spray the engine down with foot powder. Then install the alternator cover and run the bike for a few minutes without the rotor, which should give you a good indication of where the leak is coming from. I wouldn't walk away from it during this process. If something is pushing the seal out, you'll want to be there to turn it off before the thing shoots out all the oil. You'd be surprised what a quart of oil can do for making a gallon sized mess.

Anyway, that's what I'd do if it were mine.

[XJOK2PLAY]

Yeah, unless you've made the 'tap & plug' mod to the galley plug... do not start that thing w/ the cover off! It'll shoot out the whole pan of oil in about 2 seconds, and that plug will disappear forever...

(One of those... 'first you say it, then you do it' kinda moments...)

Cover holds that thing in place. There's also an O ring seal there too you can replace.

[psycoreefer]

Bad thrust bearings usually don't make a whole bunch of noise. It sounds kind of like a very light knock that comes and goes, and is usually only noticeable at idle. On these engines, with the general clackety nature of them it may not be noticeable at all. If you can feel movement, that usually isn't a good sign, but it also depends on the guy doing the checking. I always had to use a dial indicator and my mentor could feel by hand. I have never heard of a thrust bearing issue on these engines either, so chances are its all good.

This all stems from the picture that looks like something was rubbing on the protrusion that the seal is installed in. Looks can be deceiving though.

IIRC, you said you got the seals from NAPA, which I did as well, and they were a "will-fit" type of thing that didn't actually fit as well as should. They were a fractional seal that was close on the metric dimension. You may want to hit up the local industrial bearing shop and see if they can get you a proper seal. I think the ones I got were $3 a piece, but for the left side. The right side may be similar.

Also, while you still have everything apart, look closely at the surface where the lip rides. They will usually get a groove in them from the seal, and that can be OK. What is not OK is any scratches or grooves that are along the axis of the crank. For example, someone grabbed it with vice grips and then used emery cloth to smooth it over.

The seal shouldn't hold any pressure per se. The oil behind it will be from the crank bearing and what ever splashes out of there. Probably lots of volume but not a whole lot of pressure.

On last thought, it shouldn't hurt anything to run with the rotor off. You won't get any charging, and there is a possibility that the crank is drilled for oil through the bolt hole. So you might want to get a smaller bolt and put some teflon on it or other sealant and plug the hole. I don't know how the galley plug is held in, but i have heard of them popping out, which I think was mentioned in this thread. However, I have ridden mine several miles with the ignition side cover off, while trying to adjust the vacuum pod and had no problems. So, you might just unplug the regulator and spray the engine down with foot powder. Then install the alternator cover and run the bike for a few minutes without the rotor, which should give you a good indication of where the leak is coming from. I wouldn't walk away from it during this process. If something is pushing the seal out, you'll want to be there to turn it off before the thing shoots out all the oil. You'd be surprised what a quart of oil can do for making a gallon sized mess.

Anyway, that's what I'd do if it were mine.

First off, I was concerned about Napa listing the seal as a close fractional seal as well, but when I got it this is what it looked like




As you can see the box lists it as 32x45x7, and if you view the full size of the seal and zoom in you can see that it has those dimensions stamped on it, I'm putting more trust in the stamping on the seal then the napa parts book, should be the "exact" right size.

Anyways when I pulled it apart this is the back of the rotor....

It does look like it has some rub marks on it, but they aren't even as deep as the machine marks on the un-rubbed portion. I tried using some feelers but if you look closely you can see there is a lip on the back of the rotor that prevents feelers from being able to get in there, I'd have to use some plati-gauge or something, and I don't have any. If it does rub its not much because I can turn it by hand even when pushing in on it. It sort of feels like, and looks like maybe the rubbing was on the gob of RTV the PO put on it.

Finally I started the motor with the rotor off, I had to hold the plug in with a pair of channel locks, the seal didn't start leaking until the motor had been running for several minutes, and it was leaking around the shaft...

After removing the new leaky seal here is the shaft and you can see the drain hole..

The shaft looks ok, no scratches I can spot, Can't tell if there is a groove or not, I don't see one and its impossible to get a finger in there to feel for one.

Now I cranked the engine with the seal out, as predicted there is a very good volume of oil that moves through there, and that was just cranking on the starter, not even running...

Out of curiosity I cut the new seal in half, and put half back in the bore, here you can see that if the seal were pressed all the way in it would nearly block off that drain hole...




When I put the new seal in I gave it a few taps and it went in a bit further then "flush" on the outside, I didn't think it was an issue, but I'm thinking now that maybe it was blocking that drain and causing pressure to build behind the seal, which caused oil to be forced past the seal, I'm going to try a different seal tomorrow and see what happens. Perhaps that is the reason Yamaha choose to use a seal with a lip on it to prevent it from blocking off that oil passage?

[psycoreefer]

F!#*ing seal!!!!

Just replaced it again, with a new single lip seal, and again rode to work and I have a drip of oil coming out the side cover! WTF is going on, it shouldn't be that hard to seal a stupid shaft! Guess maybe I'll try one of those speedy sleeves I've read about and see if that fixes it. I've got this sinking feeling that this is going to turn into one of those, I should have left it along things that ends up costing me 4 or 5 times as much as it should have!