Starter Solenoid

daoust

daoust

Member
Looking to replace the starter solenoid on my 1947 Ford convertible. A couple questions. The parts catalogs offer them with a steel case or a "bakelite" case; with or without FOMOCO script and with or without a "convenience button" on top. Which is the correct set-up in terms of original correctness?

Correct part number?
 
The steel case units with the button are out of stock everywhere. For now the plastic case/steel bracket replacement type (with the button) is all that is available.
 
Beware, I paid extra for the ford logo metal with button & the nuts holding the cables are metric.I really thought with the logo it would be American made. Oh well.
Gary.
 
Make sure your solenoid matches your polarity (there are two kinds of solenoids). Positive ground systems are triggered by grounding the small terminal. Negative ground systems are triggered by the hot (positive) wire.

Also, on positive ground systems, the large terminals MUST be correct to battery and to the starter. I learned this the hard way when I accidentally mounted one upside-down.
 
It's actually just how the solenoid coils are grounded...insulated base, as in early Ford, has the hot side permanently connected internally and starts working when you ground the other end of that circuit via the small terminal. Grounded base is permanently grounded via its bracket and needs cannection to the hot side of battery via a two pole switch, as with Fords from about 1951 and most other cars. They don't actually care about polarity, they just need either the ground side or hot side of circuit completed depending on the type. In Early Ford, hot side is always connected but which side of battery is hot doesn't matter.
 
The 41 - 48 Ford Book says, " The solenoid case is zinc plated and may or may not carry the Ford script on the topside. A button on the bottom of the switches activates the starter motor as a convenience to the mechanic working under the hood."
That being said, if everyone is out, then good luck.
 
Bruce Lancaster said:
It's actually just how the solenoid coils are grounded...insulated base, as in early Ford, has the hot side permanently connected internally and starts working when you ground the other end of that circuit via the small terminal. Grounded base is permanently grounded via its bracket and needs cannection to the hot side of battery via a two pole switch, as with Fords from about 1951 and most other cars. They don't actually care about polarity, they just need either the ground side or hot side of circuit completed depending on the type. In Early Ford, hot side is always connected but which side of battery is hot doesn't matter.
Click to expand...

Hi folks, I am trying to get a rebuilt starter for my 51 239 Mercury Flathead working so I would appreciate your help. The new solenoid doesn't 'click' but the push button on the bottom engages the starter to turn over the motor, which then starts. However the starter stays locked on - is this because the solenoid is for a negative ground, and if so what do I do about it, or do I get another starter solenoid which would be for positive ground? Thanks
 
Here is how a solenoid works. Current is passed through a coil creating a magnetic field which causes the high current contacts for the starter to connect. There are a couple of ways for this to be done. One is to have an internal connection from the battery cable to one side of the coil and the single post is connected to a switch to ground. This is how an original or one made like an original works. There are some that have an internal ground and need power to the post. If you have one of these you need to wire it differently to get it to work. If you put an ohm meter from the post to ground and have fairly low resistance you have the latter. If you have an original you need to connect the battery cable to the side that shows low resistance to the post. Later cars have two posts where one supplies full voltage to the coil bypassing the resistor making the vehicle start easier.
 
Thanks for the explanation and the reason why the new solenoid is not working the way the original did - I am on my way to test both, and hopefully this will solve the stuck starter problem! With my years of experience at this ( I have never changed either before ) I did not know if the problem was electrical or mechanical.
 
Most solenoids sold today are the "universal" type that have two small terminals. They are connected to the coil that pulls the relay. This allows it to be used in either a system that grounds the starter button or uses voltage to pull it. In the first case, one terminal is connected to the button, and the other to the battery side of the solenoid. In the second, One terminal is connected to ground, the other to the button or ring. C&G (800/266-0470) shows starter solenoids on page 140 of their catalog. If you want the original steel type with a button, order 01A-11450. If you want that one with a logo, add an "F" to that number. See the array in their online catalog www.fordparts.com
 
Thanks Supereal!

Now that I am getting familiar with this site, I am finding that all kinds of folks are having the same issues that I have been going through since 07 - some of them the trucks age, but also my lack of knowledge and simply not knowing what to ask of who, so many, many thanks ( ': o ))
 
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