testing starter solenoid

[Kenneth Cole]

I have my solenoid out by itself and want to test it. what method should I use? When it was in the rig it would disengage from the starter several times before it would finally stay engaged long enough to start the engine. Once the engine was warmed up she would start right away.
1991 Humvee
Thanks
Ken

 

[Mogman]

As far as I know there is no real way to test it off of the starter, the plunger retracts as it pushes the starter drive into the flywheel and at the bottom of its stroke forces the contacts to power the starter motor.
There are several reasons a starter just "drops out" sometimes it is the starter motor itself as the current that keeps the solenoid activated actually goes through the starter (the solenoid coil is usually "grounded" through the starter not directly to ground) so any interruption in the current flow, say a bad brush can cause the starter to drop out.
You should be able to disassemble it and clean the contacts which are the most common wear point in the solenoid itself.

 

[Dieselmeister]

You can apply 24 volts to the solenoid and check if the plunger solidly retracts, and cannot be pulled out under power. Your solenoid could be dropping out for two reasons. One is a weak solenoid (cooked coil or bad internal connection), or, while your starter is engaging, your voltage gets pulled so low that the solenoid drops out. This would be caused by a bad connection, or weak / bad battery.