1990 merceriser alpha1, gear oil in bellows and yoke seal leaking air

[landover50]

​ 1990 merceriser alpha one
1990 merceriser 5.7l

I recently bought a boat. He stated he had recently changed the bellows himself so I wanted to check to make sure there was no water in it and instead of finding water I found a bunch of gear oil. He said he has never had gear oil in it before and this would have happened in only a couple trips in the water.

​​​​​I'm not sure if I believe him but if he is telling the truth, is it normal for the yoke seal to go bad that fast? Or is this a symptom of something else?

I pressurized the outdrive and sprayed soapy water around the seal and you can see in the picture it is producing bubbles. I just wanted to get some opinions from the experts on here and if it is a yoke seal, some tips on how to proceed. Also if there is anything else I should be looking for and replacing while I'm at it. I've been doing my reading (lots on the forums here, excellent info) and watching videos as well. Not an expert but handy enough to get most things done.

Thanks in advance for any help....
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[Bt Doctur]

yoke seal and/or yoke shaft

 

[landover50]

That's what I thought.

I called a shop today and the owner told me there is no reason the yoke seal should fail other than water in the outdrive. Is that accurate?

Here is a pic of the gear oil after sitting for a day. It seemed to be a little lighter when it first came out but nothing crazy. Once I get into the drive, what other evidences of water should I be looking for?

Also, when pressure testing, what are the specific failure points I should be checking? E.g. yoke seal, lower drive seal, drain plugs etc.

 

[Bondo]

Is that accurate?

Ayuh,...... Welcome Aboard,...... No that's not accurate,..... just normal wear could do it,.....

 

[vetting]

Yeah not accurate. The upper gearcase yoke itself can also wear to the point where it just wont seal at all no matter what you do with the actual seal. Check the yoke itself for groves. I just replaced mine due to a grove that was worn in it. I had the exact same issue with gear oil blowing into the bellows.

 

[achris]

Agree, not a true statement. A couple of years ago my drive leaked oil into the bellows. Having owned it from new (and installed it myself) I knew it had never had water in the bellows, it was just a worn yoke. I set the new seal 40 thou deeper in the carrier so it's running on a 'new' surface. Problem solved.

Chris...

 

[landover50]

Thanks all for your replies.

I was able to get the upper u joint/gear assembly removed. With a stroke of luck, the yoke still looked great with no grooves. The old seal was a little brittle, it would crack when I manipulated it.

After removing, it appears that I have the bearings with the small spacer so no need to do rolling torque, correct? Just torque the nut down per the manual?

Also, when I pulled the spacer and shim, the spacer it's cracked. It is the thicker, black ring. It was the very first part in the assembly. Is this something that I can just go purchase or do I need to get a caliper on it to know exactly what to get? Picture below.

What is the best way to clean up the bearings, racers, etc before reassembling?

 

[landover50]

I was just reading and sounds like the thick shim is supposed to be split?

 

[achris]

I was just reading and sounds like the thick shim is supposed to be split?

Correct. Looks like a piston ring.

 

[landover50]

Perfect.

A couple more questions as I'm getting into this.

The metal washer that goes over the shift shaft is severely concave (center of washer pushed down). Pretty sure it should be flat?

Also, what it's the best way to clean up the upper bearings, racers etc prior to reassembling?

TIA

 

[Rick Stephens]

Might as well post pictures of the bearings. If they are rusted on the retainer, that is often the case as any water at all evaps into the airspace at the top and sticks to the race. Anything corrosion at all on the rollers or race and the bearings should be replaced.