Re: revisiting starting issues on 2126
Posted by HH56 On 2023/8/6 13:45:55
There is a relay inside the Autolite gear reduction starter solenoid assembly that is powered by the starter switch or pushbutton. When the relay comes in it is what actually commands the solenoid to pull in. If the car still has the safety circuit intact, ground to the relay is provided by going thru the generator armature windings and brushes. One of the brushes is connected to ground which is ultimately where ground for the relay coil is found. All generator wiring must be connected and brushes in good shape for that circuit to work. Some cars have had the circuit bypassed by disconnecting the wire from one of the small relay coil terminals on the solenoid from the ARM terminal of the regulator and connecting it directly to the block to provide the ground. The other terminal still goes to the starter switch.
The solenoid for the Autolite gear reduction starter has two coils that get power from the relay at the same time -- a pull in coil and a hold coil. The pull in coil gets its ground thru the windings of the starter motor so that connection and brushes inside the motor need to be good. Once the pull in coil does its job and has the solenoid plunger pulled in so the copper disc makes the connection with the terminals to provide the battery voltage to the motor, that battery connection effectively puts the same voltage on both sides of the pull in coil so it turns off and is no longer able to work. The solenoid is then kept in position by the energized hold coil which is grounded to the solenoid case. It will keep the plunger pulled in and motor spinning until the start switch or pushbutton is released and relay drops out. The hold coil by itself does not have the power to pull in the solenoid.
If the solenoid has not been reconditioned there is a possibility wear and arcing or burning of the copper disc or more likely, the copper end of the large terminals where the connection is made could be causing the no engagement. The bottom illustration where the arrows point to the switch contact gap shows the area where wear is prevalent. Sometimes there is a semicircular spot worn by the contact disc on one or both terminals that is so deep the disc can no longer make contact.
On the fuse, are you sure it is between the solenoid and voltage regulator or could it instead be between the solenoid and overdrive relay.
Attach file:
47 starter circuit.JPG (86.58 KB)
Autolite solenoid.jpg (86.56 KB)
The solenoid for the Autolite gear reduction starter has two coils that get power from the relay at the same time -- a pull in coil and a hold coil. The pull in coil gets its ground thru the windings of the starter motor so that connection and brushes inside the motor need to be good. Once the pull in coil does its job and has the solenoid plunger pulled in so the copper disc makes the connection with the terminals to provide the battery voltage to the motor, that battery connection effectively puts the same voltage on both sides of the pull in coil so it turns off and is no longer able to work. The solenoid is then kept in position by the energized hold coil which is grounded to the solenoid case. It will keep the plunger pulled in and motor spinning until the start switch or pushbutton is released and relay drops out. The hold coil by itself does not have the power to pull in the solenoid.
If the solenoid has not been reconditioned there is a possibility wear and arcing or burning of the copper disc or more likely, the copper end of the large terminals where the connection is made could be causing the no engagement. The bottom illustration where the arrows point to the switch contact gap shows the area where wear is prevalent. Sometimes there is a semicircular spot worn by the contact disc on one or both terminals that is so deep the disc can no longer make contact.
On the fuse, are you sure it is between the solenoid and voltage regulator or could it instead be between the solenoid and overdrive relay.
Attach file:
47 starter circuit.JPG (86.58 KB)
Autolite solenoid.jpg (86.56 KB)
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