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Electical problems in WD45

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Terry Geer

03-05-1999 18:10:20




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I have a WD45 that won't start. I know it is in the electrical but don't know where. I know it gets the electricty up to the coil. When rolling over it doesn't even pop or move the raincap. Thanks in advance.




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Dave Fullmer (TN)

03-05-1999 22:41:35




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 Re: electical problems in WD45 in reply to Terry Geer, 03-05-1999 18:10:20  
Terry, you say that it gets electricity to the coil. I assume you measured it with a voltmeter, correct? The question is was this voltage pulsating? The flow of electricity is from the battery to the points, breaking with the points and then to the coil. The on/off battery voltage at the primary of the points causes a step up voltage back into the distributor rotor and then to each spark plug in turn. When checking for spark on my WD and WD45 I usually pull the center wire off the distributor, take the cap off the distributor and hold the wire end close to a ground point WITH AN INSULATED PLIERS. Then I use a screwdriver to open and close the points. You should get a spark out of the coil wire. If I do then I make sure that rotating the engine causes spark. If no spark, my points aren't set right. Set the points according to specifications and try again. If you understand what is supposed to happen, usually you can take it one step at a time and track down the sequence until you find where your spark is escaping. Hope this helps

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Gordon Chance

03-06-1999 11:03:37




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 Re: Re: electical problems in WD45 in reply to Dave Fullmer (TN), 03-05-1999 22:41:35  
Dave: I agree with everything that you have told Terry, but I must take exception to the flow of electricity you gave him. The flow of electricity goes from the battery to the ammeter to the switch to the COIL first, then through the primary windings of the coil and then to the distributor and points. The electrical current has to go through the primary windings of the coil first to build up a magnetic field when the points are closed. When the points open then the flow of current stops and the magnetic field collapses across the primary and secondary windings in the coil to cause a small buildup in voltage in the primary winding, (which the condensor absorbs to stop sparking across the points), and a large buildup of voltage as the magnetic field collapses across the thousands of windings in the secondary windings and create the voltage necessary to jump a spark across the plug. The easy way to tell if the points are causing the problem or the coil is bad, if you know that you are getting voltage to the coil from the switch, is to check for voltage on the distributor side of the coil. If you are showing voltage on the distributor side of the coil when the points are open, then you know that the primary winding in the coil is good. You should not see voltage when the points are closed. If you have voltage when the points are closed then they are not making good contact to ground and you will not get a flow of current through the coil to build a magnetic field to collapse and create a spark. I hope that this explanation helps. Gordon

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Dave Fullmer (TN)

03-06-1999 19:35:01




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 Re: Re: Re: electical problems in WD45 in reply to Gordon Chance, 03-06-1999 11:03:37  
You're right, Gordon. I guess my brain went into overload for a minute and got confused. Hope I didn't confuse anyone else.



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Gordon Chance

03-07-1999 05:35:55




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 Re: Re: Re: Re: electical problems in WD45 in reply to Dave Fullmer (TN), 03-06-1999 19:35:01  
Dave: No harm done. I usually find your answers to peoples questions to be right on but I couldn't let this one pass by. Keep on posting your good answers. With regards. Gordon



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Dave Fullmer (TN)

03-07-1999 18:40:41




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 Re: Re: Re: Re: Re: electical problems in WD45 in reply to Gordon Chance, 03-07-1999 05:35:55  

Thanks Gordon, I've been thinking about this thread all day and other questions are coming up. I need to get my meter out to the tractor tomorrow and check a couple of things. Isn't the primary and the secondary windings connected at the negative side of the coil? If that's the case then the points are in series with both windings.



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Gordon Chance

03-09-1999 20:31:11




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 Re: Re: Re: Re: Re: Re: electical problems in WD45 in reply to Dave Fullmer (TN), 03-07-1999 18:40:41  
Dave: I checked a new coil today with my ohmeter to satisfy my own curiosity. I found that there was 4 ohms of resistance through the primary wires and 6,710 ohms of resistance from either primary terminal to the coil output terminal. There is some connection between the primary and secondary windings, but at a very high resistance so it basically acts like there is no connection for any current to flow through. So only the primary windings are in series with the points as the other end of the secondary windings is connected to the output terminal of the coil to the center of the distributor cap. I learned something today and just thought that I would let you know what I found. Have a good day. Gordon

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Terry

03-10-1999 09:59:26




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 Re: Re: Re: Re: Re: Re: Re: electical problems in WD45 in reply to Gordon Chance, 03-09-1999 20:31:11  
Thanks guys, your information is great, now all I
have to do is figure out a way to print it so
that I can follow your advice. I will post my
results so that you can see if it helped
This was my first time on this website and I could
not find my way back for a while to check for
answers. This just shows what I have always known
that old iron buffs love to help out other tractor lovers.
thanks again.
Terry

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Gordon Chance

03-08-1999 17:55:40




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 Re: Re: Re: Re: Re: Re: electical problems in WD45 in reply to Dave Fullmer (TN), 03-07-1999 18:40:41  
Dave: I'm not 100% certain but I don't believe that the primary and secondary windings in the coil are connected at all. I could be wrong as I haven't checked this out with an ohmeter. I believe that if they were connected that you would get some backfeeding of the high voltage through the primary winding and sparking across the points more than the condensor can handle. The high voltage that jumps across the spark plug is an induced voltage from the collapsing magnetic field when the points open.I don't mean to be too technical but I believe that this is the way that it works. I'll check a coil with an ohmeter tomorrow to see if my theory is correct. Have a good day. Gordon

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Dave Fullmer (TN)

03-09-1999 23:31:50




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 Re: Re: Re: Re: Re: Re: Re: electical problems in WD45 in reply to Gordon Chance, 03-08-1999 17:55:40  

I'm positive the spark is a result of the induced voltage from the primary to the secondary coil. Years ago when I studied some electronics one of the experiments was to take an old TV power supply transformer, hook it up across a 1.5 volt D cell, and then hold on to the leads while disconnecting the battery. You can not believe the impact of that collapsing field. But back to our thread, I did run accross a instruction on checking for polarity of the secondary in an old Motors handbook. When I get it figured out and try it I'll let you know what I found.

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Dave Bowers

03-08-1999 04:15:00




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 Re: Re: Re: Re: Re: Re: electical problems in WD45 in reply to Dave Fullmer (TN), 03-07-1999 18:40:41  
Sounds like a compression problem, if the weather cap doesn't pop. Dave and Mary Bowers



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Dave Fullmer (TN)

03-09-1999 23:23:35




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 Re: Re: Re: Re: Re: Re: Re: electical problems in WD45 in reply to Dave Bowers, 03-08-1999 04:15:00  

Hunh?



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