What causes breaker points to pit

[charlys1954]

 Last summer my 1968 Mercury 20hp was running bad, took it apart and the points where pitted. Sanded them down and it ran ok for a little while, they pitted again. Found NOS points and condensers last winter and will be installing them. I don't want to ruin the new points so I'm wondering what causes points to pit. Is a bad condenser what causes points to pit or can other things cause pitting.

[Mac Attack]

bad capacitor or moisture.
After gapping the points run a pc of cardboard thru them to clean them.
Sometimes oil or grease is on a feeler gage or your fingers.
This will also cause this.
Good luck

[charlys1954]

That's what I was thinking but wasn't sure if a weak coil could cause pitting. The condenser must of been the problem then because I did run a clean pc of heavy paper thru them several times when I worked on them last summer.

Hopefully the new points/condenser will keep it running for a few more yrs. I should replace it cause the start pulls like dragging a cement block down the road with a rope, I broke 3 last year. Just hate to get rid of an vintage motor.

[Mac Attack]

A week coil will cause high current because of low voltage.
The higher current could cause the pitting.
So yes, that too is a possibility.

[charlys1954]

bad capacitor or moisture......

After reading your post again it made me think, could moisture be getting into the points. They are not sealed inside the stator, the dust cover does not have a gasket so is it possible on these old motors that moisture can find its way in. If that's so I don't see any way to keep it out.

[charlys1954]

A week coil will cause high current because of low voltage.
The higher current could cause the pitting.
So yes, that too is a possibility.

I'll have to do some research on testing the coils with my multimeter. I know I've done that before but can't remember the process or what the resistance is suppose to be. Tks for your help Mac, appreciated.

I'm coming to the conclusion if this summer is like last summer I'll look for a different more modern motor. I'm wanting to fish Maxy and Webster this year, can't do that without a reliable motor. I can only fish small lakes, don't want to get stranded on bigger water.