replacing oil seal in alpha one gen one upper driveshaft housing

[ethan169]

1985 Wellcraft Scarab I
350 crate motor replaced a merc 260. Has alpha one gen one out drive. I dont really have any serial numbers as they are all painted over or missing..

So I pulled my drive off at the end of the summer last year and lots of gear oil came out from the drive shaft bellows area. Looks like my upper was passing oil.... like a lot of it.

I just bought the boat and only had it on the lake for a couple of hours just to see if it ran or float etc. Seemed to do ok but I didnt go crazy with it since I didnt know much about the boat yet.

Anyway I suspect that the oil seal on the horizontal drive shaft is bad. I guess I assume thats what keeps the oil in the drive right? Is this something I can replace my self? It looks like I need a special tool to remove the drive shaft. And theres some shims I need to get everything back together right? Everything else looks like its in good shape. Everything I can see anyway like the u joint and drive shaft etc..

Should I just bring it to a shop and have them go through it? I havent read too many posts about people disassembling these units.

Thanks for any information!

 

[achris]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

If you have the tool for removing the cover, then you can do the job yourself. Do you have a service manual (seloc and clymer are NOT service manuals, they are nasty horrible imposters)...

Have a read of the manual and decide if you want to attempt it yourself.. If you do, come back and we'll hold your hand for the duration...

Chris........

 

[ethan169]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

If you have the tool for removing the cover, then you can do the job yourself. Do you have a service manual (seloc and clymer are NOT service manuals, they are nasty horrible imposters)...

Have a read of the manual and decide if you want to attempt it yourself.. If you do, come back and we'll hold your hand for the duration...

Chris........

I do have a factory service manual (pdf) for the alpha one. I printed out the section on the upper gear housing it seems to have all of the steps. However it does use a handful of special tools.

As for the tool to removing the cover is that the bearing retainer nut deal? Is that special tool really necessary? I understand I cant just take a screw driver and hammer and take it off that way but i must be able to make some sort of tool to remove it. The tool is a bit expensive for a limited use tool. $80 or so....

I wonder if I could rent one from a local shop or just bring it in and have them loosen it to the point where i can take it off by hand. then assemble it at home and bring it in for them to tighten it.

this is the kit that I was going to get. Unless you think I can just find the one oil seal. I figure i can replace most of it though while i have everything apart.
Teleflex Marine 18-2648 Upper Unit Seal Kit : Amazon.com : Automotive

 

[sheboyganjohn]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

Look on E-bay for the spanner wrench. I just ordred one for $10 plus $5 shipping.

 

[ethan169]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

Look on E-bay for the spanner wrench. I just ordred one for $10 plus $5 shipping.

Thank you! I just ordered it from ebay. Cant beat that price.

I got a local shop to quote me on doing a reseal. $300 for the job.... no thanks.

They are breaking that bearing retainer loose for me so I can start on the dissasembly until my ebay spanner wrench comes in.

Im sure Ill be back with questions as I get into disassembling things.

 

[ethan169]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

Ok so I dropped off the upper unit at a local shop to have the bearing retainer nut loosened so I can take it off by hand. For what ever reason the guy at the counter decided to tell the tech that I wantd the bearing removed.... So I walked in to this...and a bill of $65. I was planning on throwing the guy a 20 or something cash just for breaking the nut loose. It literally would have taken 30 seconds.


Anyway the money really isnt the issue. The problem is that I didn't get to take it apart. So im going to have a harder time putting it back together. I would have liked to see everything as it came out not just a pile of parts on the table.

I have a few concerns. The first one is the order of the shims for the driven shaft? The one that has the u joints and the large bearings. There are three of them. Two silver and one black that has a break in it. The break looks like its supposed to be there I think. Do they go back in in a particular order? I would have just put them back the way that they came out if I knew... Here is a picture.


My next concern is the preloading of the bearings. My two larger bearing are kept together with the gear and cups. I see how the splined smaller drive shaft fits into them with the oil seal/carrier and then a washer then the lock nut. But there is a special procedure for setting the preload. Ive attached the screen shots of that section of the manual. I have a torque wrench but not a torque meter?


What about the upper and lower oil seals? They werent leaking before but I did order an entire seal kit so If I can replace them id like to. I think getting them out should be no problem. But how do i get them back in without the "special drive tool"

And for the quicksilver maine grease. Can I just use any marine grease?

Thanks for the help! Parts are coming tomorrow!

 

[sheboyganjohn]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

Does this help at all.

 

[achris]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

ok.. The split black ring, yes it's meant to be split. It goes into the housing first, then the shims. The main issue we have is that we don't KNOW that the shop gave you back all the shims. If you re-assemble with one or some missing, the gear clearance will be wrong and you'll destroy a gear set. The other issue you have is that the pre-load needs to be set on the drive gear and bearing set. I have a video showing how that's done...

So, we put new seals in. I have never used a Merc special tool for setting seals. Sockets and small flat plates works just as well when you're careful and know what you're doing. Once you have the seals all in and the pre-load done, put the driven gear in the housing and the top cover on and torque the bolts to 20 ft. lbs.. Next put the shims in the front of the box and slide the bearing pack in. Screw the cover in hand tight. Now, check that you can just rock the drive gear clockwise and counter-clockwise, there should be clearance. You should feel the gears touch and untouch (hope that makes sense). Slowly tighten up the cover with the special tool and keep checking that clearance. If it goes tight (no clearance) STOP, there's a shim missing. If all goes well then there should be just a tiny bit of clearance by the time you reach 200 ft. lb.. It should feel like there's about 5 thou. I have no idea what it actually is, I've never bothered to measure it. It just feels like that.

Yes, any marine grease. Maybe hire a torque indicator from a auto shop.

HTH,

Chris.........

Here's the video
Bearing pre-load

 

[Bt Doctur]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

Do yourself a favor and get the original double lipped seal. National 712250.
See if the gear just slides off the bearings. if it does and you have the small spacer ring(26) you tighten the nut to 75Ft/lbs.
If not you use the rolling torque method.

 

[Levithan]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

I hate to say this as i'm not one that likes giving people money but, take it back to the marina and pay the extra 240.00 to get it done right with a warranty.
Those units are expensive and for the inexperienced can easily be mucked up and ruin your first day back out on the water.
240.00 is cheap for piece of mind with warranty.

 

[ethan169]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

I hate to say this as i'm not one that likes giving people money but, take it back to the marina and pay the extra 240.00 to get it done right with a warranty.
Those units are expensive and for the inexperienced can easily be mucked up and ruin your first day back out on the water.
240.00 is cheap for piece of mind with warranty.

Everyone has to start somewhere. If I pay them to do it I wont know how to do it next time. Why not learn on an old drive like this one? Worst case scenario I gets completely destroyed. I can then buy a used complete drive off of craigs list for anywhere from $200-$800 and be back where I started. It would suck but its unlikely if I take my time and ask questions and understand what im doing.

ok.. The split black ring, yes it's meant to be split. It goes into the housing first, then the shims. The main issue we have is that we don't KNOW that the shop gave you back all the shims. If you re-assemble with one or some missing, the gear clearance will be wrong and you'll destroy a gear set. The other issue you have is that the pre-load needs to be set on the drive gear and bearing set. I have a video showing how that's done...

achris - I'm fairly confident that the shop gave me all the shims that came out. Despite them not listening to my original request they did have everything in a box and all the loose smaller parts in a plastic bag. I hadn't been to the shop before but it does look legit. I just thing the guy behind that counter didn't listen or understand my original request.

As for the seals I think i will be able to manage installing the new ones with various sockets and extensions and a press etc. I just wast sure if people have done that successfully or not.

Everything you wrote in your previous post makes sense and agrees to the service manual that I have read a few times. The upper drive shaft house section anyway. I am still a little unclear about the bearing preload though. As I mentioned my bearing assembly and drive gear are one package right now. I can move the outer bearing cups independently from the drive gear but they do not come apart. Im not sure I understand how they are held together without the drive gear to u-joint nut (#23). The bearings I assume are pressed onto the drive gear shaft? Its a bit difficult to tell from the break down posted by sheboyganjon. Right now that whole assembly seems a tight so I dont know who did the previous preload. If they went to far I understand I have to disassemble correct?

BTW I was able to borrow a torque indicator from the machine shop at work.

Thanks again for everyone's help. I should get the seal kit in the mail today so this evening I plan on attempting the re sealing and re-assembly.

 

[mercs4mark]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

Until you remove the nut on the drive gear you won't know what type you have, if the bearings slide off then look for a small spacer, then just torque the nut back down upon reassembly, if the bearings do not just slip off then they are pressed on and you have to use the Rolling torque method upon reassembly

 

[ethan169]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

Until you remove the nut on the drive gear you won't know what type you have, if the bearings slide off then look for a small spacer, then just torque the nut back down upon reassembly, if the bearings do not just slip off then they are pressed on and you have to use the Rolling torque method upon reassembly

As you can see in the first picture in post #6 the drive gear and bearing assembly are removed form the splined drive shaft. The lock nut is off.

The bearings are not loose from the drive gear so from what you've posted earlier i do not have the spacer and I need to use the rolling torque method to set the preload properly. Right?

Now my concern is that I wasnt the person to set the preload initially. It could have been the original mercruiser tech that assembled it back in 1980 whatever or it could have been some hack. My bet is the later... So my question is this - if you over tighten when setting the preload the manual says you need to disassemble and start over. So should I do that? Or is it fair to assume that since its most likely been like this for a long time and everything looks to be in good condition (except the drive gear shaft oil seal) so it was set correctly to begin with. In this case I would perform the rolling torque procedure following the manual and the video that achris posted above.


Heres the picture again of how things are right now.


Thanks again

 

[Glastron_V210]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

There are 2 specs for bearing pre-load (Or rolling resistance). One is for a new bearing, one is for a used bearing, used being used for any period of time.

I did the same seal job as you, and did my own preload. the used preload seemed a bit tight...there was a bit too much rolling resistance for my liking. It wasn't quite 'free' enough. I backed it off a touch, and set it there. It's much like setting a wheel bearing.

Check out this link:

Replacing your Mercruiser Alpha Upper Gears


From Don on another post:

If you are re using the bearings, then you shouldn't be using the 6-10 in lb. spec, you should be using the 2.5-4 spec.


Chay

 

[achris]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

There are 2 different bearing pack set up methods, depending on which bearing pack you have. You said that you can't slide the bearings off the drive gear, which means that are an interference fit on the drive gear shaft = No small spacer, rolling torque method. You need to use a press (or some other method. I use my press at home, so can't give you a cheats method) to just back the bearings off the drive gear a little so you can start the set-up procedure. Have you watched my video yet?

Chris...

 

[achris]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

Just read G-V210's post... DO NOT back the nut off once you get the right rolling torque. Do that and the bearings will chatter under load, that's why there is supposed to be pre-load, so the bearings don't chatter, fatigue and fail prematurely...

Chris.......

 

[mercs4mark]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

You still need to set the rolling torque, but before you do play with that gear and bearings a little, I have had gear lube hold the slip on type and then all of sudden they sliped off just saying make sure they are pressed on and if so you have to separate them a hair to unlock the load and then reset the load by rolling torque method

 

[mercs4mark]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

With Chris do not back that nut off after set

 

[ethan169]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

Ok,

I did try to separate them with my hands. Didn't want to damage anything but they sure seem like they are pressed on. I will double check though.

acrhis - I do have a press both mechanical and hydraulic if needed. Also have a large bearing puller bracket. Not sure what the actual name is but I know ive got access to one. Could you give me a description of how you separate yours just to be sure im not doing it in some weird way that may damage something. I seem to recall a section in the service manual about removing the bearing so I will re read that as well. Unfortunately I have the disadvantage to not seeing everything completely disassembled (regarding the bearing pack)

I did watch your video this morning. I will have to review it but as I recall you don't separate the bearings at all. I assume you already did that or didn't need to.

 

[achris]

Re: replacing oil seal in alpha one gen one upper driveshaft housing

acrhis - I do have a press both mechanical and hydraulic if needed. Also have a large bearing puller bracket. Not sure what the actual name is but I know ive got access to one. Could you give me a description of how you separate yours just to be sure im not doing it in some weird way that may damage something. I seem to recall a section in the service manual about removing the bearing so I will re read that as well. Unfortunately I have the disadvantage to not seeing everything completely disassembled (regarding the bearing pack)

I did watch your video this morning. I will have to review it but as I recall you don't separate the bearings at all. I assume you already did that or didn't need to.

The plate you're referring to is called a bearing separating plate (looks like this 3'' Chromium Molybdenum Steel Bearing Separator). I slip that between the gear and the bearing, and tighten up the nuts slightly, just enough to move the bearing away from the gear a hair. And yes, it will be tight. Then start the set-up procedure. And yes, I'd already done that before the video was started.