1975 Johnson 6hp 6r75r gearcase.

Rad2101

Seaman
Joined
Aug 3, 2011
Messages
52
Hi there,

Trying to get an old oil leak sealed up in my little 6hp. Ive managed to source the seals and o-rings etc and have it all apart ready to go. Just had a question about the oil seal. Diagrams attached show the oil seal (49) and a head and bearing (48). All references to the bearing and seal show them as separate parts. In looking at the bearing and spares on the web pages this appears to be a single assembly as shown. Is the oil seal a part of this assembly and can it be removed and replaced or does the entire assembly need to be replaced. It looks to me that the oil seal is in the end of the bearing assembly. Obviously I don't want to damage it any further and hoped someone might have an answer.

cheers
 

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racerone

Supreme Mariner
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Dec 28, 2013
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I believe there was a change made to the OD of the seal and there may be a different part # 313282--It is shown as an assembly for that reason.-----Pop the seal out and measure it to get the replacement.
 

F_R

Supreme Mariner
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Jul 7, 2006
Messages
28,195
Some---that is SOME years had a pressed-on fish line guard washer, which supposedly kept you from accessing and replacing the seal. Of course we all knew that all you had to do was pop the washer off and replace the seal as always. Yes, there are a couple of seal sizes.
 

Rad2101

Seaman
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Aug 3, 2011
Messages
52
Many thanks there. So I should be able to pop the seal out without too much trouble.?

cheers
 

F_R

Supreme Mariner
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Well yes and no. Some people find them a challenge. But yes, however you can push/shove/pull it out will work.
 

Rad2101

Seaman
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Aug 3, 2011
Messages
52
Ive managed to get this out and replace now. Many thanks to all. NO oil leaks so far.:):):):)
 

Crosbyman

Rear Admiral
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Nov 5, 2006
Messages
4,904
very important to cut the spaghetti seal square against the prop shaft oil seal carrier

did you change the shift rod seal (O ring) and the drive shaft seal under the water pump
 

Rad2101

Seaman
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Aug 3, 2011
Messages
52
Hi guys,

Well this worked for me for a while. Started leaking again a month after my last post. Should I be using any sealant here. My thinking was the rubber O ring and seal would do the job. Maybe I need to add some RTV or something to the surfaces. Any further advice. Cheers
 

Rad2101

Seaman
Joined
Aug 3, 2011
Messages
52
Yeah I replaced it all. Oil leak is low down either from the prop shaft seal or one of the O rings. I've looked around a bit more and I see many advising the use of 3M 847 gasket sealant on the mating surfaces of the lower gearcase. Ive replaced all the seals and O rings but it looks to me like its coming from the prop shaft still. It may be running down so it appears to come from the prop shaft. The 3M 847 sealant isn't available in Australia. Can someone advise of a suitable replacement.

Many thanks once again
 

jimmbo

Supreme Mariner
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May 24, 2004
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12,944
What condition was the shaft where the seal would contact?
 

racerone

Supreme Mariner
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Dec 28, 2013
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36,031
The bearing on the forward gear was properly lined up with the pin ?----Was gasket replaced under the upper bearing housing ?
 

oldboat1

Fleet Admiral
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Apr 3, 2002
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9,598
No question it's gear oil, not fuel/2-cycle/water running from a vent hole somewhere?
 

Rad2101

Seaman
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Aug 3, 2011
Messages
52
All good here. Definitely gear oil. Its got its own smell. I've cleaned up all around the prop and shaft so any small leak will be noticed. Definitely coming from prop shaft seal. either from inside or outside of seal. Hard to tell. As I mentioned earlier all seals and gaskets were replaced. Initially I sealed it up with blue RTV. I've since re opened and cleaned it all up again. I'll try it again with a nice thin layer of blue RTV again (unless someone can tell me not to). Maybe I didn't get enough on the Oring around the seal carrier. I'll pay more attention to detail this time and make sure it all goes together smoothly. Maybe I put the oil back in too soon last time as well. This time I'll seal it all up and leave it a week before I put any oil back in it.

thanks
 

Rad2101

Seaman
Joined
Aug 3, 2011
Messages
52
Sorry has taken me a while to get back to this. After the second rebuild and re seal of this gearbox I finally filled it with oil after having it sit there for months empty of oil. After two weeks and having run it several times on the water. No leaks for two weeks then it just started leaking again. OMG!! This is killing me. I had left it sitting in the warm sun on a hot day and it started leaking again. Maybe the extra heat and expansion has opened up a small gap somewhere. Dunno where to go from here.Rebuild again, probably need to replace all the seals again since it has been opened a few times again.
 

racerone

Supreme Mariner
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Dec 28, 2013
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Some will argue-----You need to do a pressure test on this gearcase !!
 

boobie

Supreme Mariner
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Nov 5, 2009
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Have the gear case pressure and vacuum checked and it will save a lot of "peeing" around. JMO.
 

tomhath

Master Chief Petty Officer
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Dec 5, 2007
Messages
814
If the vacuum/pressure test checks out, here's another thought.

When you fill the gear case do you have the motor upright, and only fill from the bottom hole until it flows out of the vent hole?

There needs to be some air inside the case because the oil will expand/contract with temperature changes; overfilling it with lube will cause it to force some out when it gets hot.
 

racerone

Supreme Mariner
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Dec 28, 2013
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If the lower unit is properly sealed where would the oil come out if it got hot ?
 

Crosbyman

Rear Admiral
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Nov 5, 2006
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don't overfill it and you won't have any issues to worry about !

in any event if oil gets watery change it at mid summer and at lay-away
 
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