40 hp shifting problems

[dogpaddlin]

I have a 1970 model 40hp Johnson with Electromatic shift that is giving me shifting problems. I had a post several weeks ago regarding this, but the problems have changed. I took the boat out last week and the transmission would not engage in order to back off of the trailer. When I wired around the switch the transmission engaged and ran fine. After this diagnoses I replaced the factory switch in the control box with a two position toggle switch.

I took the boat out today and it ran fine for a while. No problems backing off the trailer and it took me to the other side of the lake with no problems. Once at my fishing hole the story changes. I tried to move from one spot to another and the motor would not push the boat. I wound up paddling/drifting back across the lake. This is the 4th time I have gone to the lake and had problems with the shifting. I am at my wits end. Any suggestions would be GREATLY appreciated.

 

[F_R]

Re: 40 hp shifting problems

We could sit here and type out a whole bunch of guesses. But it still all comes down to you have to troubleshoot the system yourself by first checking the voltages at the green and blue wires at the rear of the powerhead, leading down to the lower unit.

If you have battery voltage on green in forward gear and on blue in reverse gear, but no shifting, the trouble is between there and the lower unit clutches. If you don't have the voltage there, the trouble lies between there and the shift switch, ignition switch, and clear back to the battery, including the ground.

Get yourself a voltmeter and use a logical approach and you will find the trouble.

 

[steelespike]

Re: 40 hp shifting problems

Is the toggle switch rated for the amp load of the solinoids?

 

[dogpaddlin]

Re: 40 hp shifting problems

The switch is rated for the coils. I have ohmed everything out and it showed acceptable readings. When in the drive way you can put power to the coils and it will engage. It spins the prop with no problems, but then when at the lake it will not.

Is there a chance that maybe my water pump is not working, causing it to get hot and the clutch releasing, or would that simply shut down the motor?

Please forgive me if I am asking ignorant questions, this is the first boat I have ever worked on and it has been a learning experience! I have not been able to find anyone in my area that is willing to work on old boats, so this forum is my only chance of getting this thing running.

Thanks in advance.

 

[58CorrySuburban]

Re: 40 hp shifting problems

Hi,

I'm new to boats/motors too. If you've run it in the driveway, you should be able to tell if the pump is working by warm water coming out of the leg.
Also, if it is fine in the driveway, but fails at the lake ("under load") maybe there is something loose/slipping.

Looking at the exploded view of your lower unit, it seems if something like the prop shaft was loose the gears would slide and engage freely at first, but after some torque and friction (getting to the other side of the lake), could they be getting "wedged" or stuck apart.
Shaft could be like this, " -- " in the driveway when it has no resistance, but be slightly like this, " / " under load. This might prevent engagement. Just throwing it out there being that we are both new to boats. I could be completely wrong.

Do you have a service manual?

If you didn't get one yet, may I suggest buying the OEM style. I made the unfortunate purchase of a SELOC manual for my 1958 Evinrude Bigtwin 35 hp and it covers your exact motor too. This should give you a certain indication about the detail provided by a Selco.

 

[dogpaddlin]

Re: 40 hp shifting problems

I have a Seloc manual that I am pretty happy with. Kind of reminds me of the Haynes and Chilton manuals I have used for repairing my old jeeps.

One more question. If there is water mixed with the oil in the lower unit, could that cause the gears to work intermittently? The only reason I ask before I check is I just changed the oil in the unit and I cannot find the OEM stuff here locally. I hate to drain it and not be able to refill it if that was not the problem.

Thanks.

 

[charliedaubitz]

Re: 40 hp shifting problems

I hate to drain it and not be able to refill it if that was not the problem.
Thanks.

drain it into something clean, if it's water free, pump it back in. You can usually loosen the bottom screw and see the water come out if there's any in it.
be sure to check your battery voltage, those clutches require a hot battery and a working generator to keep it that way.

make sure your rubber in the prop hub isn't wornout and letting the prop slip on the hub.