82 Johnson 25 hp steaming, slipping

[vasportsman]

Hello all, new to the forum as I just became a boat owner.

I have an 82 Johnson 25hp 2 stroke pull start tiller style outboard attached to a 16 ft Jon. When I bought it, it ran great, started right up, was perfect. The next time out, had a few problems, and wondering if anybody has experienced anything similar or knows what is wrong.

First, noticed that in addition to exhaust there seemed to be steam coming out of the exhaust, or what seemed like the exhaust, honestly I have not been able to nail down where it is coming from, and the exhaust does not come through the propeller.

Second, the upper part (out of water) of the lower unit was very warm/hot to the touch.

Third, the telltale was warm, but not hot, and had a steady stream, not pounding, but not trickling either.

Fourth, after running for awhile (10 mins) at higher RPMs, it began to slip out of gear and rev high with no forward movement, I would let it come down, and it would re-engage at low and made it back to the dock with no further problems not running above about mid speed/turn.

I have been trying to diagnose the issue, and drained the gear oil and found it to be a bit milky, which I understand is a sign of water intrusion, and very green in color (is that just a function of the kind of oil?) I have refilled it, however it did not take hardly any gear oil, and not much drained out, but was overflowing out of the top fill hole when trying to add more. I plan on a test run this weekend hopefully, either just off a dock or in a garbage can.

Gear oil issue, or something more problematic?

Thanks!

 

[jasper60103]

Re: 82 Johnson 25 hp steaming, slipping

The slippage sounds like a worn clutch dog. Since the gearcase is not taking oil, you may want to tear down and inspect the gear case anyway. You can check your water pump as well. Be sure to post some pics of your findings. Good luck.

 

[kenmyfam]

Re: 82 Johnson 25 hp steaming, slipping

Check the cooling system, put new upper and lower seals on the drain / fill screws and check again before tearing down any further for water intrusion. Check also for a spun prop. See "Top Secret Files" for info and also use the search function if necessary.
Post your findings for everyone's input and welcome to iboats.

 

[jasper60103]

Re: 82 Johnson 25 hp steaming, slipping

Oh, another thought. Check the shift linkage. That could also cause gear slippage if loose.

 

[vasportsman]

Re: 82 Johnson 25 hp steaming, slipping

Thanks for the input!

Really hate to tear the the lower down with my limited technical and mechanical knowledge, but how else do you learn?

So do you guys think the gear slip could be unrelated to the heat? Still wondering about the steam, I am going to call previous owner tonight and see if he has any further knowledge of this problem, really did not want to do it, but it seems necessary.

Will keep you all posted, and thanks.

VAS

 

[steelespike]

Re: 82 Johnson 25 hp steaming, slipping

You may have a bad thermostat on the upper end of the head.
If you don't know the age of the pump it should be changed anyway.
Slip sounds like a spun prop hub.
A bad clutch dog feels like you hit something when it slips.
A spun hub just revs and usually reengages when you slow the motor.
When refilling the gear case you fill through the drain hole till it comes out the top "vent" hole.
Then insert the top vent screw and tighten before removing the gear lube tube.Then quickly insert the drain screw.
The gear case will hold about 8 ozs of lube.
Filling at the top hole would be difficult because it can't vent properly with the oil going in.
Its possible that someone put grease in thinking it would solve the slipping.

 

[vasportsman]

Re: 82 Johnson 25 hp steaming, slipping

Update

Well, took it out this weekend after I got the gear oil figured out, seemed to run better and steam less, and I believe the steam is coming out of the exaust. After more research I do believe the hub is spinning after running awhile at high RPM, what is the fix for this?

Also, I am still concerned about the heat being generated by the lower unit, I guess a new water pump and/or thermostat is probably in order, but the motor itself does not seem to be running hot, just the upper part of the lower unit above the vent screw to the head of the motor. It is metal, and not plastic if that helps.

Thanks again.

 

[steelespike]

Re: 82 Johnson 25 hp steaming, slipping

If the prop is from 82 a new prop is a more cost effective for a spun hub.
The present size should be under the prop nut or near the base of the blades.
A Solas Amita or Rubex have a good reputation.
After running the motor; very carefully feel the head.Should be too hot to hold your hand on but not so hot it burns you.
The Thermostat is on the top of the head under a little thermostat housing.
You should have a factory service manual. Reprints are available here.

 

[jasper60103]

Re: 82 Johnson 25 hp steaming, slipping

Hmmm. I'm having a tough time visualizing where the steam is coming from. I know my exhaust leg just below the power head can get pretty warm to touch.