Gear Oil Leak - Possible Yoke Seal

Hey guys,

Over the past two seasons I've noticed that my gear oil in the reservoir drops slightly over the year during use, to where i have to add enough to bring it up from the low level line to the fill line. I know it is probably the yoke seal after reading other posts in this forum. After removing the drive the past two winters I've noticed a small amount of gear oil (4oz. or so) in the bellows. So today I decided to pressure test the drive to make sure that the seal is in fact leaking.

I turns out the drive held 15psi for 10 hours today without dropping a smidgen, even while rotating the u-joint shaft I sprayed a soap solution looking for leaks and didn't see any. I assume that this is now only leaking when the drive oil is warm.

Questions are:

1) Does this warrant a yoke seal replacement even though no visible leak is present? (I can't figure out any other place oil could get in the bellows)
2) Assuming I have the bearing set that requires the rolling torque method, is this something a certified shop should attempt and then again, should I trust them to be certain to set the torque correctly? Or is this something a decent shade tree could perform...such as myself...I don't have a dial type torque wrench but could probably get my hands on one?
3) Is it absolutely necessary to remove the top cover of the upper gear case or can this repair be performed without removing the top cover? (Looking at the exploded parts view I don't see it necessary, but the O&M manual is unclear as to whether the cover needs to be removed.
4) With the yoke assembly out and even though I have no u-joint problems, should I go ahead and replace the permalube u-joints with the greasable type?

thanks,
Keith

Re: Gear Oil Leak - Possible Yoke Seal

1). the only place gear oil can be getting into the bellows is through that seal, or the 'O' ring associated with it. Personally, I'd replace both.
2). You have a Gen II drive, so you need to use the 'rolling torque' method of setting up. If the shop is a certified Mercruiser workshop, the techs SHOULD BE trained to do the job correctly. Is it something you can do? If you're mechanically inclined and have a reasonable degree of skill, yes. But I would recommend you have a torque indicator AND a press handy...
3). No... just use the Merc special tool to remove the castellated lock ring from the front and pull the bearing pack and drive gear out. That's the other thing you'll need, the special tool... -> http://www.iboats.com/Mercruiser-Sp...6203570--session_id.756192546--view_id.269858
4). Unless the unis need to be replaced, leave them alone....

Chris......

Re: Gear Oil Leak - Possible Yoke Seal

thanks achris.

I feel this is something I can do, getting the rolling torque is the only step that worries me a little.

I have a fair bit of surface rust on the u-joint and yoke assembly and that is why I felt it may be best to go ahead and clean up the components and replace the u-joints, as well as I find it hard to tell if they are bad by sight and feel. I'll post some pictures later today to show you the surface rust.

You stated that I need a press, is this for pressing the new oil seal into the carrier or is this for removing the bearings?

Also, if I have to replace the yoke does this require re-shimming of the gears or is that only necessary when replacing bearings?

Thanks,
Keith

Re: Gear Oil Leak - Possible Yoke Seal

A little surface rust on the u-joint assembly.


more surface rust on the u-joints


Pressure test rig, in case someone is interested in how I performed it.

Re: Gear Oil Leak - Possible Yoke Seal

[Pressure test rig, in case someone is interested in how I performed it.
View attachment 143875[/QUOTE]

Did you presure check with lube in it?
Thought I saw some in the clear tube......

Pretty sure the drive should be empty.......

Re: Gear Oil Leak - Possible Yoke Seal

FreeBeeTony, the drive was empty.....that's just an oil stained hose.....I used a piece of tygon from an old gear lube filling bottle.

Re: Gear Oil Leak - Possible Yoke Seal

Ohhhh.....never mind.

Re: Gear Oil Leak - Possible Yoke Seal

kwoolard said:

thanks achris.

I feel this is something I can do, getting the rolling torque is the only step that worries me a little.

Click to expand...

Follow the manual and you'll be cool... I assume you have a bench vice to work with... And the genuine workshop manual.. (Let me know if you don't)

kwoolard said:

I have a fair bit of surface rust on the u-joint and yoke assembly and that is why I felt it may be best to go ahead and clean up the components and replace the u-joints, as well as I find it hard to tell if they are bad by sight and feel. I'll post some pictures later today to show you the surface rust.

Click to expand...

You check unis by moving them slowly through their range and feeling for any roughness or 'stepping'. Also rock them, looking for slop. No slop and smooth throughout their range, leave them be.

kwoolard said:

You stated that I need a press, is this for pressing the new oil seal into the carrier or is this for removing the bearings?

Click to expand...

You need the press to press the bearing off the yoke to start the rolling torques et up...

kwoolard said:

Also, if I have to replace the yoke does this require re-shimming of the gears or is that only necessary when replacing bearings?

Click to expand...

Re-shimming only require when the housing, the bearings or the drive gear is replaced...

Re: Gear Oil Leak - Possible Yoke Seal

Thanks achris, i'm going to disassemble tomorrow after I get my spanner wrench cut out on the laser tomorrow.....nice to work at a place that goes through a lot of scrap stainless steel sheet metal.

The local shop stated 2.5-3 hrs for the repair, not bad but i'd much rather do it myself.

I definitely have the manual (the right one), bench vise, etc., only thing I'm missing is the dial inch-lb torque wrench but think I can get my hands on one.

Re: Gear Oil Leak - Possible Yoke Seal

I removed the u-joint assembly today and am still trying to get my hands on a dial torque wrench before disassembling to replace the seals. I wanted to check the rolling torque on the assembly prior to disassembling to just get a feel for it before I started.

In the meantime I have a question:

Looking at the gear assembly, the bearings are pressed onto the gear shaft. So why is it necessary to remove the bearings from the gear shaft if all I'm doing is replacing the seals?

I understand I still need to make sure the rolling torque is correct, but is it necessary to completely remove the bearings from the gear shaft or even just separate them a little to completely reset the rolling torque?

Thanks
Keith

Re: Gear Oil Leak - Possible Yoke Seal

You have to remove the seal and its carrier off over the gear end of the shaft, it won't pass the unis.... You undo the nut holding the gear to the shaft and pull the entire bearing pack/gear assembly off the shaft, then the seals and retainer ring will come off. Be VERY attentive to the way it disassembles. If you get one of the part ***-about it will be a pain...

Chris....

Re: Gear Oil Leak - Possible Yoke Seal

achris said:

You have to remove the seal and its carrier off over the gear end of the shaft, it won't pass the unis.... You undo the nut holding the gear to the shaft and pull the entire bearing pack/gear assembly off the shaft, then the seals and retainer ring will come off. Be VERY attentive to the way it disassembles. If you get one of the part ***-about it will be a pain...

Chris....

Click to expand...

I understand that everything slides off towards the nut end of the yoke, but when the gear/bearing pack come off, aren't the bearings pressed onto the gear? If so, my question was why is it necessary to remove the bearings from the gear, and then reinstall them? Can't I just replace the seals and recheck the rolling torque without removing and reinstalling the bearings.....seems like a wasted step?

Keith

Re: Gear Oil Leak - Possible Yoke Seal

Once you remove the nut you release the tension on the bearing pack, but because they are an interference fit you need to get the first bearing off the shaft so it can get the right tension again. Sure, you could just nip the nut up without doing the torquing, but you'd be back here with "My top box grenaded, why"

Chris....

Re: Gear Oil Leak - Possible Yoke Seal

thanks achris,

So just to summarize/clarify, I don't have to remove the bearing closest to the gear only the bearing closest to the u-joint end? And do I need to completely remove it or just back it off slightly so the nut can pull it back together? I seem to recall DonS stating that if you got the bearings too tight during the rolling torque method you simple hit the bearing with a dead-blow to create the separation you need and start over with the rolling torque method again. I don't see how that is any different than what I'm trying to accomplish. I just want to be sure as I don't want to get it wrong and ruin the drive, but don't want to remove any unnecessary parts if don't have to in replacing the seals.

I still haven't found the time to get into this project other than removing the assembly from the gear case, which took only a couple of minutes. Gears look good and the o-ring is completely compressed flat, so I bet that is contributing to my leak as well.

Probably would have had it back by now if I took it to a mechanic but there is nothing better than the feeling of fixing something yourself and knowing you've got it right....at least for me anyway.

Re: Gear Oil Leak - Possible Yoke Seal

achris said:

Once you remove the nut you release the tension on the bearing pack, but because they are an interference fit you need to get the first bearing off the shaft so it can get the right tension again. Sure, you could just nip the nut up without doing the torquing, but you'd be back here with "My top box grenaded, why"

Chris....

Click to expand...

Yes then you have what I do in my drive......

Re: Gear Oil Leak - Possible Yoke Seal

rickryder said:

Yes then you have what I do in my drive......

Click to expand...

Best thing you can do with that is this -> http://www.boatmotors.com/motorparts/index.cgi?pid=7535&flag=2&cyl=8&year=1987&state=none

Re: Gear Oil Leak - Possible Yoke Seal

yep, I think there was more to that failure that just the rolling torque being improperly set........looks like lack of lubrication to me.

thought I'd share this with you guys: i went to the local boat yard and asked the head of the service department about setting the rolling torque on the gen II drive upper bearing set and he gave me this blank look. i knew the guy, personally, and have borrowed tools from them in the past and asked him if I could get my hands on his dial torque wrench for setting the rolling torque and come to find out, no mechanic in that shop has one in their tool box......claims he has never set the rolling torque on a gen II drive.

guess I won't be taking my boat their for service any time soon.

Re: Gear Oil Leak - Possible Yoke Seal

Is he an authorised Mercury service agent?

Re: Gear Oil Leak - Possible Yoke Seal

Supposedly so, he's definitely an authorized Mercury dealer.

Hey Chris, any comment to my last question regarding only the bearing removal of the one closest to the u-joints? I'm not sure if both bearings come off together or if they can come off individually....looks like I can remove only the bearing closest to the u-joints and leave the gear end bearing in place, but not certain if that is an acceptable method.

Re: Gear Oil Leak - Possible Yoke Seal

Yeah, that's the way I do them. Just slip the one closest to the unis off a little (only needs to be a few millimetres) and make sure the other one stays down with the gear, right on the shoulder....

Chris....