R/R clutch in 79 6hp Johnson Model 6r79e

[fredskid]

Could I get some advice on whether or not to tear open this motor and work on the clutch? It's my dads motor, starts great, runs great, just slips under load. He took it in to a shop, mech. said it was the clutch and would be around 300 to repair. we are fairly handy, have time, just would like to know this. Is the 300 too good to pass up? Can we get parts? if so is this some thing we should partake in. Dad's on a fixed income and I don't need another motor! Thanks for your help...,mike

 

[CATransplant]

Re: R/R clutch in 79 6hp Johnson Model 6r79e

First, let's make sure you have a problem with the clutch dog. You say it "slips under load." What exactly happens? Is there a big jerk when it does this, or does the engine just speed up without pushing the boat faster?

Way, way too often, a slipping prop hub is the problem. If that's the case, then replacing clutch dogs won't help one bit. Replacing the prop, however, will solve that problem.

So, describe for us, in as much detail as you can, what happens when it does what you call "slips."

 

[JB]

Re: R/R clutch in 79 6hp Johnson Model 6r79e

What CAT said. Find out what is really wrong before doing anything.

If it does need a clutch dog (less likely than prop or shift linkage adjust) the price of the OEM Service Manual http://www.iboats.com/mall/?category_id=251023&view_id=251023 and parts will come to a LOT less than $300.

 

[CATransplant]

Re: R/R clutch in 79 6hp Johnson Model 6r79e

Many years ago, my father sold a 16' Glasspar Avalon with a Fat Fifty on it. A few months later, the buyer contacted him and said that he had paid a shop a bunch of money to overhaul the lower unit, but it still didn't work right. It was "slipping," he told my father.

Well, there was a spare prop that went with that boat, so my father told him to put the other prop on the outboard and go try it. Sure enough, that was what it needed, since it was just a spun hub. Boy was that guy ticked off at the repair shop.

As a final note to all of this, my father sold the guy the boat and motor in 1986 for $500. Last year, he bought it back from the guy for $500. It still starts in about 2 seconds cold, and still has that "spare" prop on it. He sold his 23' boat and is now back to using the Glasspar. At age 83, he decided that the 23' was a bit much for him to launch and retrieve solo.

That's when I learned to always identify the problem before fixing the problem. My Dad loves to tell that story. He was an auto mechanic all his working life, and just about the best diagnostician I've ever encountered. A customer would come into the shop and describe a problem. My Dad would ask a couple of questions, then think for awhile, and ask maybe a couple of other questions. Then, he almost always knew what the problem was.

 

[jay_merrill]

Re: R/R clutch in 79 6hp Johnson Model 6r79e

If it does turn out to be the clutch dog, here is parts breakdown of the 1979 6hp gearcase, just to give you an idea of what you are getting into.

You can also see this diagram directly at the following link - when you get to the opening page, looks for the "Parts" tab and follow the links until you get to the gearcase diagram for the 1979 Johnson 6hp.

http://www.shop.evinrude.com

Part #44 is the "Shifter, Clutch dog" and the manufacturer's price is $107.08. If the forward and/or reverse gears are rounded off at the tabs that engage the clutch dog, you will have to get them "cut" at a machine shop. This will be true if your local mechanic does the work, as well. Price for this just depend on where you go but you should be able to get it done for under $100. If you have to buy new gears, manufacturers price for the forward gear (#39) is $195.70 and for the reverse gear (#46), it is $39.50.

I agree with the others, however, and recommend that you check other things before cracking the gearcase opne. If all you have is a "spun prop," you might just be looking at a $30 - $50 hub replacement.

 

[iwombat]

Re: R/R clutch in 79 6hp Johnson Model 6r79e

As an aside CA, I wholeheartedly suggest picking up a copy of _Surely You're Joking Mr. Feynman_ and reading the chapter called "He Fixes Radios With His Head!"

 

[fredskid]

Re: R/R clutch in 79 6hp Johnson Model 6r79e

we felt it was not a slipped hub, and here were our reasons, while we were under power, it felt like we were hitting the bottom or stumps, a lurching motion. I have slipped a hub on my mariner, which was a constant crawl at low speed, no matter how high the rpm's. Not sure if this matters we could turn the motor over, while in gear, turning the prop by hand. I will check the prop again, however! measure twice cut once.

 

[F_R]

Re: R/R clutch in 79 6hp Johnson Model 6r79e

Yep, "hitting a log, Hitting a stump, hitting a 'gator, all clsssic stories of a jumping clutch dog. Props slip smoothly, dogs jump.

 

[CATransplant]

Re: R/R clutch in 79 6hp Johnson Model 6r79e

As an aside CA, I wholeheartedly suggest picking up a copy of _Surely You're Joking Mr. Feynman_ and reading the chapter called "He Fixes Radios With His Head!"

Isn't that a great chapter? I read it several years ago, and it cemented what my father taught me about problem diagnosis.

 

[CATransplant]

Re: R/R clutch in 79 6hp Johnson Model 6r79e

Yup. Sounds like a bad clutch dog. I just wanted a better description of what "slipping" was on your engine. You can do it yourself, but you will definitely want a manual for that job. With that in hand, you'll get 'er done.

Sorry it wasn't just a prop hub. That's a heckuva lot easier to fix.