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  1. #1

    Join Date
    Oct 2003
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    Sullivan County, Indiana \"God\'s Country\"
    Tractor
    1955 Ford 640

    Default solenoid

    Okay, I promise this is the last question on my 640's starting solenoid. If I can't get it figured out, I guess I will just convert to 12v and forget the whole darn thing!

    I get nothing when I hit the strarter button. To start it,I must jump across the solenois posts. I have replaced the solenoid, a three wire one, with another three wire unit off of another 640. I know it works, since I saw the other tractor start with it. Looking at the wiring diagram, I am sure I have it wired right. A wire from the solenoid to the starter, a wire from the battery (negative) to the solenoid, a wire from the solenoid to the regulator (?), and a wire from the solenoid to the starter button.

    When I first got the tractor, I could get a spark by touching the wire to the starter button on anything metal, noe I get nothing when I do that. Why? Could the problem be the starter button? I am getting really tired of having to get off of the tractor and jump across the poles to get the blooming thing started!




  2. #2
    Epic Contributor Soundguy's Avatar
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    Default Re: solenoid

    Well.. first off.. .that 3 terminal 6v pos grnd solenoid.. should only have 3 wires.. and there should be NO connection to the regulator.

    If still pos. grnd... the neg cable from the battery to one big lug, the other big lug to the starter post. The little terminal.. which by the way MUST point toward the tractor block, has a wire that goes to the big thumb switch. All that thumb switch does is ground the wire... theoretically, you could take that small wire off, and just touch it to the tracor to crank the starter. And the 3rd little terminal has to point toward the block, as the solenoid is wired 'internally hot', and that is dependent on which side of the solenoid is hooked to the battery.

    My gues is that you have the solenoid backwards, or that the thumb switch is no longer making contact.. or that this extra wire you have from the regulator is causing the problem.

    To test the thumb switch and solenoid.. hook it up like it is sopposed to and hit the thumb switch.. by the way.. it will only start in neutral.. it is interlocked. If it doesnt.. take a jumper wire, and jumper that small wire to ground.. again.. making sure you are in neutral.

    Since you say the solenoid works on another tractor , and that you can jump to get the starter working, then that isolates the problem to:
    1, instalation
    2, thumb switch
    3, small wire from thumb switch to the solenoid.


    I've got a 2n, an 8n, and a NAA That 3 wire solenoid was used for lotsa years.... let us know what you find.

    Soundguy

  3. #3
    Epic Contributor
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    jinman's Avatar
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    Texas - Wise County - Sunset
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    NHTC45D, NH LB75B, Ford Jubilee

    Default Re: solenoid

    Everyone of those old Fords that I've ever seen originally had a solenoid with a button on the bottom. Pressing the button would manually close the solenoid contacts. That was what was on my Jubilee until it suddenly welded the contacts one day and the starter kept going after the engine started [img]/forums/images/graemlins/shocked.gif[/img]. I had to pull the battery cable to stop it. [img]/forums/images/graemlins/tongue.gif[/img] The replacement solenoid did not have the button. Anyhow, if your solenoid is one of the originals, it might have the button which could save you jumpering around the solenoid. Actually, getting the solenoid wired correctly as Soundguy said is what you really want to do. If the solenoid is not off another old Ford tractor, the solenoid may not be wired like the original. I'd wire up the large solenoid terminals and then use a voltmeter to check which small terminal has the 6 volts. That's the terminal you want to run to your starter switch. You can check it by grounding it to the tractor to see if the starter works before you do the final hook-up.

  4. #4
    Epic Contributor Soundguy's Avatar
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    Default Re: solenoid

    Great follow-up post!

    Soundguy

  5. #5
    Epic Contributor
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    Default Re: solenoid

    ...not that great [img]/forums/images/graemlins/blush.gif[/img] [img]/forums/images/graemlins/laugh.gif[/img] It just dawned on me that his whole problem is probably that the wire from the battery and the wire to the starter are reversed. I should have told him to use a voltmeter on resistance scale to check continuity from the starter terminal to the small wire. If he reads continuity, the main solenoid terminals need to be reversed as I think you indicated in your post. [img]/forums/images/graemlins/cool.gif[/img]

    It's amazing what half a day of thinking a problem through can produce when your old and slow like me. [img]/forums/images/graemlins/shocked.gif[/img] [img]/forums/images/graemlins/grin.gif[/img]

  6. #6

    Join Date
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    Sullivan County, Indiana \"God\'s Country\"
    Tractor
    1955 Ford 640

    Default Re: solenoid

    Okay, here is what I have found so far. First of all, I was wrong on where all the wire went. I said one went to the regulator, it goes to the ammeter.

    I reversed the starter and battery wires as advised and got....nothing. [img]/forums/images/graemlins/confused.gif[/img] I checked the center post with a volt meter and get no voltage, not even any continuity between it or the the other posts. Shouldn't there be continuity?

    I may just throw in the toweland wire up a push button swithch between the starter and battery cable. Hate to admit defeat, but I am thoroughly perplexedby this. It has to be something simple I am overlooking, but I sure can't think of what it is. Is the solenoid from an 8N the same as the one that goes on a 640? If so I can try one more time by taking one off of a buddies tractor. I hate to buy yet ANOTHER solenoid, I am up to 4 right now!

    I will check some more tomorrow when I get home fdrom work. Too cold now, minus 5 and my barn is unheated. In fact, this thing is bothering me so much, I may take half a day leaveto work on it in actual daylight!

    My wife finds this all very amusing, apparently I am "becoming obsessed" with it.

  7. #7
    Epic Contributor
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    Default Re: solenoid

    Kirt, the best I can offer you right now is a schematic of your electrical system (attached). If you look at the starting motor relay (solenoid), you will see that there really is a wire going to the ammeter as you indicated, from the battery side of the solenoid. The other large connector goes to the starter. If you have only one small terminal it has to go to ground through your starter button. Internal to the starter solenoid, the small terminal goes through an electromagnetic coil to the battery side of the solenoid. When you ground the small terminal, current goes to ground and the electromagnet closes the solenoids contacts. It's just that simple. I'm as baffled as you are, because if there is no continuity from the small terminal to either of the large terminals, it's indicating that the solenoid is bad. Did you check the same thing on your old solenoid? You didn't get them swapped by mistake did you? Hey, I'm grasping at straws....sorry.

    Also, are you sure your battery terminals are clean? I know you said the starter worked if you jumpered around the solenoid, but could that have been a one-time fluke? If your terminals are dirty, that could be the reason you are having problems now.

    Don't let this get you too frustrated. Keep telling yourself there has to be a logical solution. [img]/forums/images/graemlins/crazy.gif[/img] [img]/forums/images/graemlins/smile.gif[/img]
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  8. #8
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    Default Re: solenoid

    Kirt, the advise you have from Soundguy and Jim should have got you going so something else must be going on here. First I recall a safety switch on the top of the transmission in series with the starter button. The starter button shorts the coil of the solenoid to ground through the safety switch.

    The original solenoid was a four terminal device connected as follows:

    1. Large post to battery
    2. Another large post to starter motor.
    3. Small post connected to the large post that is connected to the battery(this is connected to the ammeter and the tractor ignition)
    4. Another post which is connected thru the safety switch to the starter button.


    I would not assume the solenoid you pulled from another 640 has the same functionality as the original. First it is a three terminal and an alternate coil configuration is possible. If you found no continuity between the large posts and the small post. Check for continuity (several ohms) between the small post and the solenoid case. If so this solenoid requires power to the small post as opposed to ground to actuate.

  9. #9
    Epic Contributor Soundguy's Avatar
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    Default Re: solenoid

    Pull that solenoid of fthe tractor, and check it on the bench with your ohm meter and a battery. Wire the ohm meter across the two pig studs.. set for continuity Juse a jumper wire to hook one big post to -. Choose the big post to the right o fthe little post, with the little post facing away from you. Next hook a jumper wire to the little post and touch it to the + side of the battery. When you do this, the ohm meter should swing to zero.. or next to zero, and you should hear a click from the solenoid. If it does click and no ohm meter reading.. I assume the contacts are burnt up inside. If it doesn't do anything, for the heck of it, swap it around and try it again with the little post facing you.. etc.

    The starter interlock safety feature is nice.. if you can find a way to not bypass it it would be great.

    As a worst possible scenerio, if you get yet another solenoid.. get a 4 post isolated one... not a 4 post resistor bypass one.

    Wire the big studs to the battery, and the starter.. doesn't matter which one where. Then one little post will wire to the - battery stud on the side of the solenoid with a little jumper.. the other little stud is going to + ( ground ) thru your thumb switch. That keeps the starter interlock in place.

    Now there's a thought... use your ohm meter to check the thumb switch. check from ground to the little screw tab on it... when you push the button, meter should swing to zero.. or next to zero... if it doesn't.. make sure you are not in gear, and try again.. if still noting.. you have a bad thumb switch... they are replaceable for about 20 bucks.. and you have to pull the tranny top cover.. If you do.. watch out for a little detent ball held in with a spring for a shifter rail.. don't let it fly or drop into the tranny.. just ease everything up to take the spring tension off slowly. At this point you can also inspec the interlock mechanism under the tranny cover to make sure it isn't 'broke' preventing starting by blocking the switch.. etc.

    Soundguy

    Soundguy

  10. #10

    Join Date
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    Location
    Sullivan County, Indiana \"God\'s Country\"
    Tractor
    1955 Ford 640

    Default Re: solenoid

    Okay, update time! There is good news and bad news [img]/forums/images/graemlins/crazy.gif[/img]

    I believe I have, with your help, solved the solenoid problem. I hooked it up just as Soundguy suggested, and it works fine. I get voltage where I shouls and I can definitely hear the solenoid clicking now.

    The bad news is that my starter now seems to have gone belly up! [img]/forums/images/graemlins/mad.gif[/img] This has actually been coming for a while now. For the past several months it has been necessary to tap the starter occassionally with the handle of a large screw driver to get it to turn over. Now it won't do anything at all, tap or no tap. I am getting voltage to the starter now, so I feel confident that the problem is now with the starter.

    Which brings me to my next question. Is there some special trick to getting the starter off? I removed the cable and the three bolts, but the starter won't come off! I can move it back about 4 inches and turn it, but it won't come off. There is some type of shaft that goes from the starter itself on past the engine flywheel. Is it necessary to take the oil filter canister off, after draing the oil, to get the starter off? I assume I can get the starter re-built when I get it off.

    I am going to the NH dealership tomorrow to get me a real manual. Right now I have the IT manual and it is kind of light on many crucial details. It doesn't even have a picture of the starter in the manual. I may be somewhat mechanica and "handy", but with this tractor I am a real greenhorn!

    Jinman, you were right about how the solenoid works. I was just making the thing way more complicated than it had to be, I sometimes have a knack for that.

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