Weird electrical problem - 6V neg ground

Ziggster

Well-known member
Was testing the engine (C59A) starter circuit yesterday on my speedster build. Had a bunch of issues with the wiring (all done by myself), of which I think are sorted out.
However, there is an issue with both solenoid coils. When “engaged” both make a “chattering” noise. It’s very noticeable and loud. One solenoid is for the engine starter, and the other is for my radiator cooling fan. Both are “Standard” P/N SS558. I think the issue is that I’m designed the wiring for 6V neg ground, and the solenoids are designed for a 6V pos ground. At least this is what I read by one reviewer of the solenoid on the Summit website. I still have the original box and instructions for the solenoid. Should mention, that these solenoids only have three studs. Two for the “power”, and one for the coil. Tested them as per the instructions, and it would imply my solenoids are ”insulated” and not “grounded”. I believe this is the issue. I assumed they were “grounded” cases, and “grounded” them via mounting bolts to my metal battery case, which in turn is bolted to a metal plate that the battery (-) post is connected to via a (1/0) cable. All cables to the starter, solenoid, and battery are (1/0). I even have a (1/0) ground cable from the engine block to the same bolt as the (-) battery ground. So, should be no issues with voltage drop on the “power” sides of the wiring. Some background info:

1. Engine starter was rebuilt several years back and remains 6V.
2. Battery is 6V and is also several years old. Was not properly maintained over the years, but did show 6.5V before starting this testing. Had charged it for maybe a couple of hrs a few days prior. Old school (dumb) charger showed it fully charged after that time.
3. Engine will crank, but slowly. I can see the vent markings move as. Eng rotates.
4. Tested the solenoid with both “power” wires removed and nothing happened. Coil did not engage. Used a jumper wire direct from battery (+) post to coil stud on solenoid.

Any help would be appreciated.
 

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The wiring instructions are not for your solenoid. Note your solenoid has just one small terminal. It either uses the mounting or is wired internally to one of the large post internally. Believe you should check it out with an ohmmeter. Your most likely removing one of the battery polarities when the solenoid picks up and it returns when the solenoid drops out, this will cause the chattering.
 
The wiring instructions are not for your solenoid. Note your solenoid has just one small terminal. It either uses the mounting or is wired internally to one of the large post internally. Believe you should check it out with an ohmmeter.

Check for continuity, ohms, between post #2 to #3. If you have continuity, this is the diagram:

561646


If this continuity indicates an open connection between 2 and 3, then the ground is via the mounting bracket.

561647
 
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I looked up the number and that is the correct solenoid for the early Ford so the small terminal needs to be grounded to energize the solenoid.
 
Agree. Problem is solved. Tested solenoid, and there is continuity between the “BATT” and “S” terminals. Same as first pic in previous post (terminals 2 & 3). I originally had the +12V wires going to the non-BATT terminals, so flipped the solenoids upside down so they could reach the “BATT” terminals. Switched IGN circuit so that it grounded the circuit as mentioned. Works now as it should. No noise/chatter from the coil. Battery is still weak as engine still cranks over very slowly even though it was on the charger all night (6V @ 6A). Load tester says the battery is still weak. Will see if keeping it on the charger today will help.
 
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