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Results 1 to 10 of 10
  1. #1
    Join Date
    Jun 2011
    Location
    Ontario Canada
    Posts
    101

    Default 1970 85 hp v4 Johnson

    I've got a 1970 V4 85 hp Johnson. It's really clean, better than average condition, compression is 125 psi all around. The motor is throwing a lot of problems at me, ignition and gear shifting.

    #1. Ignition. No spark. At all. Old style distributor under flywheel, with amplifier and coil. Amplifier is getting it's 12 volt supply. No voltage is sending to coil, from amplifier. I checked with an oscilloscope. I suspect it's the amplifier but at over $300 I would like to be sure. Any other diagnostic tests?

    #2. Hydro-electric shift. Symptom is no neutral. Neutral shift position renders forward gear, as does forward shift position. Reverse shift position renders....reverse. Voltage on two solenoid shift wires is correct. Select neutral, green wire carries 12v. Select reverse, green and blue wires @ 12v. Select forward, no volt either wire. All testing done dry, plugs out, crank motor over with starter.

    Is it possible that my observed "forward gear in neutral" is the prop shaft sympathetically spinning but not engaged? It sure doesn't look like it. That prop is going fast. How could I gently load it, without hurting myself or the lower unit? Failing that bit of wishful thinking, any ideas as to the culprit? I am really reluctant to open the hydro-electric up.

    Finally, given that both these problems are with systems that were very short lived by OMC standards, should the motor just be retired?

    Thanks.

  2. #2
    Join Date
    Sep 2010
    Location
    ontario
    Posts
    9,596

    Default Re: 1970 85 hp v4 Johnson

    Prop will spin when in nuetral with a no load condition ( in the driveway on a hose ) nothing to be concerned about.----------These electric shift units are wonderfully simple and very reliable too!----I normally use a piece of wood to stop the spinning.-------------These units in good condition will shift from forward to nuetral after about one turn of the crankshaft.-----It will always be in forward with the motor not turning / running.

  3. #3
    Join Date
    Jun 2011
    Location
    Ontario Canada
    Posts
    101

    Default Re: 1970 85 hp v4 Johnson

    Regarding the shifter: I tried using a piece of wood to arrest any parasitic drag while shifted in neutral. No luck. That prop is hooked up, spinning with great force. There is without any doubt, no neutral function. Any ideas?

    Thanks

  4. #4
    Join Date
    Sep 2010
    Location
    ontario
    Posts
    9,596

    Default Re: 1970 85 hp v4 Johnson

    Check ohms on shift solenoid at the motor.------------One lead on green and one lead on the gearcase.

  5. #5
    Join Date
    Jun 2011
    Location
    Ontario Canada
    Posts
    101

    Default Re: 1970 85 hp v4 Johnson

    OK, tried that with a Triplett 630 VOM. Vintage test gear for vintage motors. Got 5 ohms. Both solenoids the same.

    Thanks

  6. #6
    Join Date
    Sep 2010
    Location
    ontario
    Posts
    9,596

    Default Re: 1970 85 hp v4 Johnson

    Oil pump is producing enough pressure to get reverse.----This means there is a problem with nuetral solenoid or valve that it operates.----Perhaps someone was in there and starting adjusting stuff that rarely needs adjustment.---------------Any history on the motor ? -----Any evidence that someone worked on this shift system ?
    Last edited by racerone; 10-14-2012 at 01:45 PM.

  7. #7
    Join Date
    Jun 2011
    Location
    Ontario Canada
    Posts
    101

    Default Re: 1970 85 hp v4 Johnson

    History of motor will take a few days to get. No evidence of recent work/tampering.

    If reverse requires both solenoids to be activated and neutral requires one, do we deduce that neutral solenoid/valves are working, at least when shifted in reverse?

    I am tempted to start jumping in temporary test circuits. 12 volts to reverse solenoid only and observe. Then 12 volts to neutral, and finally 12 volts to both. Does that sound OK to you?

    Thanks

  8. #8
    Join Date
    Sep 2010
    Location
    ontario
    Posts
    9,596

    Default Re: 1970 85 hp v4 Johnson

    No harm in testing this.

  9. #9
    Join Date
    Jun 2011
    Location
    Ontario Canada
    Posts
    101

    Default Re: 1970 85 hp v4 Johnson

    Bingo. Got it. Bad connection. All three positions working. Thanks for your help, really appreciate it.

    Now on to the "no fire" ignition.

    Thanks again.

  10. #10
    Join Date
    Sep 2010
    Location
    ontario
    Posts
    9,596

    Default Re: 1970 85 hp v4 Johnson

    Pull flywheel and check point gap.-----Check anti-reverse spring.-------clean distributor cap and rotor.------Test rotor and cap if need be.

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