LU problems 1967 Johnson 100 hp

[Jason1976]

My 1967 hydro swift boat has worked great for the last 4 season. Last year I decided to have the motor tuned up at a local boat shop. Ever sense the motor will not engage in forward or reverse with out stalling, even out of the water. The motor runs and idols great, and compression is good. When the LU is engaged it instantly comes to an abrupt stop and stalls out. I had a boat mechanic/friend look at it he believes the solenoid is engaging in forward and reverse. After he ran the motor and did a couple inspections. He's sure the issue is in the LU. Could the wrong oil or water in the lower unit cause the solenoid to short out on both reverse and forward circuits at the same time? Is the issue mechanical ? Please help if any one has had to deal with this issue or may have some input as were to look next? Thanks in advance.

 

[racerone]

Re: LU problems 1967 Johnson 100 hp

There are no solenoids in the lower unit !----The shifting is done by electro-magnets.--It is possible that both electromagnets are getting voltage at the same tiime. That will instantly stall the motor.---Was the lower unit off for waterpump work ?---Possibly shift wires are pinched , so ask the shop about that first.--Wrong oil or water in the lower unit does not cause this particular problem.---My gess is that the shift wires are touching together somewhere going down to the lower unit.

 

[Jason1976]

Re: LU problems 1967 Johnson 100 hp

Thanks for your imput! Yes the lower unit was removed and the empeler was replaced. That makes total sense if the wire were shorted out and possible touching. That's why I was wondering if the water or oil could make the contact between both circuits. I'll tear LU off and post back as to my findings. The wire harness iis a discontinued item, if it is pinch or damage is there any reason I can't use regular wire, or do you have any recommendations for this repair?

 

[racerone]

Re: LU problems 1967 Johnson 100 hp

I have lots of parts for those units.--Repairing that would be simple for me.-----Look to see where the damage is first.

 

[Jason1976]

Re: LU problems 1967 Johnson 100 hp

Raceone: good to know!! I hope to have it tore apart this afternoon. I'll keep you updated and post pics as soon as I can !! Thank you!!

 

[boobie]

Re: LU problems 1967 Johnson 100 hp

Don't run it anymore until you find out where the problem is.

 

[Jason1976]

Re: LU problems 1967 Johnson 100 hp

Could I measure resistance with an ohms meter to diagnose issue before removing LU ? If so what kind of resistance should I expect ?

 

[boobie]

Re: LU problems 1967 Johnson 100 hp

On each wire you should have 5-6 ohms between the wire and ground.

 

[boobie]

Re: LU problems 1967 Johnson 100 hp

Something else to think about. You could also have a bad shift switch. Easy to check. Disconnect the wires going down to the lower unit. Turn the key on and with in either gear make sure you don't get voltage on both wires.

 

[Jason1976]

Re: LU problems 1967 Johnson 100 hp

After testing resistance:
Forward to ground 2.9-3.4 ohms
Reverse to ground 2.7-3.4 ohms
Forward to reverse 1.5
The shifter tested ok each side ( reverse and forward) had a little over 13v on each side, not at the same time though!!.

Is it possible that my problem is the wires are shorten out ? Or does the measurements say the electro magnet is bad?

Thanks for the help, I spent the last two weeks trying to find these answers I've gotten in a few short hours !!

 

[racerone]

Re: LU problems 1967 Johnson 100 hp

???------If the 2 wires are touching you would be checking both electromagnets at the same time !!!

 

[Jason1976]

Re: LU problems 1967 Johnson 100 hp

I guess my only option to know for sure is to pull the LU out :/ . Once I'm at the point if the electro magnet tests 5-6 ohms on each side would that mean I'm safe to say there still good?

I'll post my results tomorrow afternoon. Thanks again for you're help.

 

[jimmbo]

Re: LU problems 1967 Johnson 100 hp

Just out of curiosity. Does the propeller shaft spin freely?

 

[F_R]

Re: LU problems 1967 Johnson 100 hp

After testing resistance:
Forward to ground 2.9-3.4 ohms
Reverse to ground 2.7-3.4 ohms
Forward to reverse 1.5
The shifter tested ok each side ( reverse and forward) had a little over 13v on each side, not at the same time though!!.

Is it possible that my problem is the wires are shorten out ? Or does the measurements say the electro magnet is bad?

Thanks for the help, I spent the last two weeks trying to find these answers I've gotten in a few short hours !!

If you look at your results, you will see that you are getting roughly 3 ohms or 1/2 the normal resistance. That should tell you that the coils are in parallel or in other words, shorted together.

You are lucky you haven't busted a clutch spring or twisted off a drive shaft. That abrupt stop happened because it was locked up, and normally something has got to give. Goes to prove the toughness of the electric shift.

 

[boobie]

Re: LU problems 1967 Johnson 100 hp

Agree +1..........

 

[Jason1976]

Re: LU problems 1967 Johnson 100 hp

So I'm in the process of removing this LU, any tips? I've removed the six nuts that I can see, and it won't budge. Am I missing some, or am I just not trying hard enough?

 

[boobie]

Re: LU problems 1967 Johnson 100 hp

There might be another bolt under the water inlet.