Johnson 15r79e Gearcase Rebuiling or replacement?

[mrtapes]

I have a Johnson 15r79e Outboard. There is a tremendous amount of oil leaking out of the gear case so I am planning on either replacing the seals or buying a reconditioned lower unit.
The issue I have is that I don't own any of the proprietary tools for achieving this process.
Does anyone know of any tutorials on opening the gearcase and replacing the seals and rings?
I have the lower unit off the motor and the gearcase cover seems to be seized onto the propeller housing as well.

What would you recommend? Should I just replace the whole thing?
Full replacement is probably not such a bad idea as I have found an inexpensive lower unit ($125 plus shipping) which the seller guarantees.
Thoughts?

 

[kbait]

Re: Johnson 15r79e Gearcase Rebuiling or replacement?

the Machinist detailed working on those lower units quite nicely: Lower Unit

$125 for a good lower unit is a good buy..

I had one of those w/bad propshaft seal. I pulled it out w/slide hammer puller/wood screw, and replaced. I got lucky and it was only the propshaft seal that was bad. You can test which seal is bad since the LU is already off. Drain the lube, replace one drainplug/washer, and blow through a tightly fitted hose into the other drain port w/LU submerged. You should be able to ascertain where the leak is.

Good luck!

 

[Robj]

Re: Johnson 15r79e Gearcase Rebuiling or replacement?

I would pressure test it first and find out where it is leaking from first, then decide whether or not to fix it. Pressurize the cavity to 5 psi and look for leaks. I wouldn't go any higher that 10 psi.

 

[mrtapes]

Re: Johnson 15r79e Gearcase Rebuiling or replacement?

the Machinist detailed working on those lower units quite nicely: Lower Unit

$125 for a good lower unit is a good buy..

I had one of those w/bad propshaft seal. I pulled it out w/slide hammer puller/wood screw, and replaced. I got lucky and it was only the propshaft seal that was bad. You can test which seal is bad since the LU is already off. Drain the lube, replace one drainplug/washer, and blow through a tightly fitted hose into the other drain port w/LU submerged. You should be able to ascertain where the leak is.

Good luck!

Thanks for the link to the Machinist. That's good stuff. I think that even without pressure testing anything I can tell you it is leaking in more places than one. There was a lot of oil coagulation around the water pump and oil was also leaking out the prop shaft. As long as I can get the replacement unit I think I will go that route. I can and do rebuild my carburetors and water pumps and the like, but designing all these pullers and things to do this job seems much more trouble than it's worth. No wonder shops charge so much for this job.

 

[kbait]

Re: Johnson 15r79e Gearcase Rebuiling or replacement?

Did you drain the gearcase and check for actual water intrusion? It's possible that you're seeing un-burned fuel/oil mix around the waterpump and coming out the inside of the prop. Especially if the exhaust chamber drain is plugged (hole just above gearcase 'bulge'.. Check it out before doing anything else. I'd drain gearlube.. if there's water in it, then you know seals are bad. If not, drain it, replace one drain plug, and put a hose in the other and blow into that hose. If it has a bad seal, you'll know right off. If it's sealed, then clean out that drain hole near the gearcase 'bulge'. Running rich at low idle for excessive periods will cause that sludge to build up..

Good luck!

 

[Robj]

Re: Johnson 15r79e Gearcase Rebuiling or replacement?

Pressure test first. If it leaking from the top water pump housing that is a fairly easy fix.

 

[WIMUSKY]

Re: Johnson 15r79e Gearcase Rebuiling or replacement?

Rebuilding LUs isn't that difficult.

Here's a link to the parts break down.
http://www.**********/parts/search/BRP/JOHNSON/1979/15R79E/GEARCASE/parts.html

Here's Iboats options for Evinrude. Just unsure which model would mirror 15r79e, '79 15hp?
http://shop2.evinrude.com/Index.aspx?s1=b56k5j9oa4vsjlti8eh4h9dcu4&catalog_id=0&siteid=1

The forum must block out a competitor.....

 

[mrtapes]

Re: Johnson 15r79e Gearcase Rebuiling or replacement?

Did you drain the gearcase and check for actual water intrusion? It's possible that you're seeing un-burned fuel/oil mix around the waterpump and coming out the inside of the prop. Especially if the exhaust chamber drain is plugged (hole just above gearcase 'bulge'.. Check it out before doing anything else. I'd drain gearlube.. if there's water in it, then you know seals are bad. If not, drain it, replace one drain plug, and put a hose in the other and blow into that hose. If it has a bad seal, you'll know right off. If it's sealed, then clean out that drain hole near the gearcase 'bulge'. Running rich at low idle for excessive periods will cause that sludge to build up..

Good luck!

That could be the issue as the hole is in fact plugged up, when I removed the lower unit a lot of water came out and the motor is primarily used as a trolling motor. The grease that drained out of the lower unit wasn't milky either, but more of a brownish sludge.

 

[RogersJetboat454]

Re: Johnson 15r79e Gearcase Rebuiling or replacement?

That could be the issue as the hole is in fact plugged up, when I removed the lower unit a lot of water came out and the motor is primarily used as a trolling motor. The grease that drained out of the lower unit wasn't milky either, but more of a brownish sludge.

Pressure test it, and see what you have. Like it has been said, all you may have been seeing was spent 2 stroke oil that gobbered everything up.

 

[Robj]

Re: Johnson 15r79e Gearcase Rebuiling or replacement?

Easy way to tell if you have water in the gear oil is to put some on a tablespoon, heat it up with a small torch and listen. If you hear crackling then that is the water boiling out from the oil. If you hear nothing, then there is no water in the oil. Just be careful not to burn yourself with the hot oil.

 

[mrtapes]

Re: Johnson 15r79e Gearcase Rebuiling or replacement?

Easy way to tell if you have water in the gear oil is to put some on a tablespoon, heat it up with a small torch and listen. If you hear crackling then that is the water boiling out from the oil. If you hear nothing, then there is no water in the oil. Just be careful not to burn yourself with the hot oil.

The drained gear case Oil most definitely had water in it even though it wasn't milky white. I'll have to get a tube of some sort in order to perform the pressure test. will post after I do that.