Yanmar Alternator Pulleys

[joe.baar]

We have the Yanmar 6LPA 315 hp with 211 hours on it. I just changed out the two alternator belts - a really easy job by the way - and I noticed the three pulleys the belts circulate around, especially the lowest and largest one, which must be on the crankshaft, have lightly rusty areas in the grooves. Is there some kind of treatment for this?

I would try Boeshield T-9 or some other waxy substance but I just know that would cause the belts to slip like crazy. I did get part of the rust with a wire brush. I don't know whether the engine can be started up without the belts - obviously there would be no alternator output if I did that, but then I could thoroughly clean the crankshaft pulley as it rotated.

Do I remember someone using a scouring powder like Bon Ami while the engine was turning?

Any hints much appreciated.

[RobS]

I doubt the rust is at the contact surface area of the pulley, is it?

[joe.baar]

After not exercising the engine during this past winter, yes. The old belts also had rust marks on the side surfaces that contact the pulleys. Even so, I saved them as spares because they don't show any significant wear - other than the rust marks.

[jleonard]

If it were me, I'd remove the belts and clean the rust off the pulleys. Light emery cloth or wet sand.
Rust will shorten belt life...and marine belt life is already not great.

[RobS]

Put toothpaste on the sides of the old belts and reinstall them temporarily. If its just surface rust I would think it would clean them up