1977 Johnson 85HP Leak and top end load up.

[Markedinger]

Hello everyone,

First time boat owner I have a friend that is pretty good with motors but we havent been able to figure this one out. The first issue is the load up, when we run the motor full out it seems that it is starving for gas. He sat in the back of the boat and was able to pump the bubbleand it ran smoothly. Please remember this only happens when the throttle is full open. FYI the carbs are so clean I could practically see myself in them. Secondly I have a leak in the lower unit opposite the prop so on the boat side basically. The previous owner said they just had the oil in the lower unit changed. Any ideas on how to fix it?? Thanks I hope as I become a more experienced boater I can comment on the post and help you guys out.

Mark

 

[JDusza]

Re: 1977 Johnson 85HP Leak and top end load up.

Welcome to the forum. Good stuff here.
First, high speed. Sounds like you are starving for fuel. Check fuel filter. Check fuel pump by disconnecting the fuel line at the carburetor. Wrap the end in a rag and turn the engine over. See if the fuel pump pushes fuel into the rag. Should get good spurts. Check all tank to carb connections for air leaks. If all is good here, you're back into the carb's high speed circuit looking for a block.
Second, lower unit leaks are indicative of worn out seals. There are two sets; a set around the drive shaft at the top of the lower unit, just below the water pump, and there's another set around the prop shaft, just behind the prop. If you are sure about the oil coming from below, the prop shaft seal is bad and the upper seals may still be good. The lower unit is one of those "once you're in, you're in" kind of things. If you open up the lower unit, you may as well do water pump impeller, grommets and both upper and lower seals.
The seals can be a bear to get out. I haven't found a good way other than brute force (and maybe some grinding), but, nothing you cannot do.
Good luck,
J

 

[Markedinger]

Re: 1977 Johnson 85HP Leak and top end load up.

Wow that seems like a lot I have the original manual, I am fairly handy so my only worry is that I wont be able to get it back together once I take it apart. If the ower unit had the oil changed recently as was told to me by the seller would they have automatically done the impellor and other things you mentioned? Do you know of any videos where I can see this work being done??

 

[JDusza]

Re: 1977 Johnson 85HP Leak and top end load up.

Am I misunderstanding the location of the oil leak? Boat side? Is oil leaking from a drain screw?
J

 

[Markedinger]

Re: 1977 Johnson 85HP Leak and top end load up.

No it is from where the lower unit comes together with the shaft, the seem if you would call it but I was trying to explain its leaking on the side facing the boat the "back" of the motor.

 

[BoatingCop]

Re: 1977 Johnson 85HP Leak and top end load up.

What does the leaking oil smell like? If it smells like rotten eggs, then you'll need to replace whatever seal it is. If it smells like gas though, then that is perfectly normal and nothing to worry about.

 

[Markedinger]

Re: 1977 Johnson 85HP Leak and top end load up.

The oil I use in the gas is blue and the oil that si coming out of the "leak" is considerably darker brown/black. I will check the smell.

 

[JDusza]

Re: 1977 Johnson 85HP Leak and top end load up.

Okay, so dark oil coming from the seam between the exhaust housing and lower unit at the front side. Check the lower unit oil at the drain, just a sample.
Generally, leaking lower unit seals will also contaminate the gear oil and turn it milky (not dark).
Compare to leaking stuff.
Drop the lower unit just a bit (without disconnecting the shift rod) and have a look with a flashlight.
What you see might indeed be the normal effluents our environmentalists are so crabby about.
J

 

[EvstaG]

Re: 1977 Johnson 85HP Leak and top end load up.

Have you been running it on muffs recently? I had the exact same thing happen to me with my 85HP about a week ago. If the lower unit oil was recently replaced, it is probably still a nice caramel colour. Easy enough to unscrew the drain screw slightly and check the colour. If that oil looks clean, and is a different colour than the oil dripping out of the prop/LU area, you probably have nothing to worry about: that stuff/sludge is merely 2 stroke oil that didn't end up getting burned/leaked down to that area.