I’m starting (pardon the pun) to have an all too familiar problem with the starter on my van and will have to replace it soon.
Sometimes, it won’t crank and I have to tap it with a hammer, then it starts right up. I’ve had starters go out plenty of times before. This is how I knew a few raps might do the trick.
My question is: Why does tapping on the starter make it turn over?
Thanks.
TEEJAY2
Magic.
Seriously, your starter assembly contains a coil that slides a shaft and lever assembly (called a Bendix assembly) that does two things: (1) it slides the starter motor’s gear into engagement with the flywheel ring gear, and (2) it connects contacts that complete the starter motor’s winding circuits, actually energizing the windings and making the motor turn.
These contacts tend to arc slightly as they’re engaging and disengaging, just as does any typical set of contacts suddenly contacting with 12VDC potential applied. As they do this over and over, two thing shappen: (1) a tiny amount of the surface material vaporizes from the intense heat of the spark, and (2) they develop carbon residue on the contact surfaces from that burning.
These two things eventually manifest themselves as fried contacts. Tapping the assembly with a hammer sends a shock wave through the assembly that basically causes the contacts to rub slightly and better connect through the carbon deposition. Eventaully they’ll get so bad that tapping won’t work anymore.
It’s all really magic.
The bushings wear out in the starter. And as with any electric motor, if the armature isn’t free to spin upon engagement the motor, the motor won’t function because of the dragging armature. Tapping on the motor shocks the armature where it finds a place where the drag is reduced and the motor functions. You can do the same thing with a worn blower motor. If tapping on the blower motor with a handle of a screwdriver gets it funtioning again, it pretty much says the bushings in the blower motor are worn out.
Tester
Also an excellent possibility. Why didn’t I think of that as well? I guess I’ve just become too familiar with fried contacts!
Could it be the solenoid switch? BTW what role does the solenoid switch play in all this anyway? All I know is that if it starts to go out on you, you can bypass it with a screwdriver. It’s sad that I know all the fixes and nothing about how it works. lol