Bad clutch dog or something else?

[jhetrick55]

I have a '72 Johnson 100 with the hydro-electric shift. Tonight we were out for a cruise around the lake at about 5mph. About 30 minutes in the boat just died... It ran a little rough before that, but stayed running and kept us moving. After that we couldn't drive it more than 100 yards without the same thing happening. It also would jump out of gear some. And... After the engine died the prop would still spin and it would make a ticking noise till it stopped.

My thoughts are to check the clutch dog and gears. Any have any other ideas or does this sound most likely?

 

[racerone]

I consider those units to be easy to work on.-----Go ahead and take it apart for inspection.-------Sounds like the bore for the shift piston is contaminated with dirt.

 

[jhetrick55]

Ok, I'm gonna start dis-assembling today - thanks for the input. What special tools might I need?

 

[racerone]

BIG , very big internal circlip pliers.----# W 7 I believe.-----Have 2 of them myself.---------Need long 1/4 " rod with 1/4-28NF thread to line up retainer plate on assembly.------Slide hammer with 1/4-20NC thread to pull out the pump housing.

 

[F_R]

Prop continuing to spin and click after the engine stops is entirely normal on many (but not all) motors. I dunno,, that seems to indicate the shifter piston has slid back into the pump as it is supposed to. Worn clutch dogs, while possible, are rather rare on the hydro-electric units. I'd want better verification before tearing into it.

 

[F_R]

I just checked the 1972 factory service manual, and it does show a ramped clutch dog. Those will rotate forward (and click) with the motor not running. Don't be in a hurry to fix something that may not be broken.

 

[jhetrick55]

Ok, so if there are suggestions of something other than clutch dog, what are they? I am fine with a mention of something else, but what would cause the engine to die after a minute or so of running at low RPM, or slip out of gear, or not be able to pick up speed when I try? Is it possible it isn't lower unit-related at all and maybe I have clogged carbs and the engine isn't getting enough oil? The engine seems to start fine and run at low RPM for a while but then these problems persist. I am trying to figure out where to go. Thanks!

 

[F_R]

Sorry, I can't relate engine dying with jumping out of gear. Loss of voltage to the ignition system could be one cause of it dying. Check all battery connections as a beginning point. Other than that, you need some serious electrical system training to troubleshoot that rather sophisticated system----if that is even what's happening.

On the other hand, loss of electrical power will cause the shift to go INTO forward gear, not jump OUT of forward. So, I just can't diagnose it from this far away.

 

[jhetrick55]

Makes sense. I appreciate any other suggestions to point me in the right direction!

 

[F_R]

Those engines require periodic maintenance under the flywheel. When was it last serviced? There is a silver wire spring in there that prevents the motor from running backwards (yes, it can). That spring is lubricated sparingly with an EP grease. If not lubricated, it wears out and metal dust fouls the distributor cap. Just a guess FWIW.

 

[jhetrick55]

Thats a good question. It hasn't been serviced under the flywheel since I got it last August, and I don't know the last time it would have been serviced before that.