Dip stick keeps breaking!?!

[scsmith]

My Dipstick broke off at the little pin in the cap. I drove the little pin out, punched the last bit of the rod out of the cap, turned the other end of the rod down to the right diameter, inserted it in the cap, drilled for the little pin, and I was back in business.

Then, 3 months later, it broke again!
What the heck? I wonder if there is some strange vibration at just the right frequency to fatigue the dip stick? Anyone else have this happen?
Is this a warning sign of something ominous?

[Wayne Gillispie]

Check prop balance. Change the orientation of the little pin. Where do you keep your oil level? Higher oil levels and thicker oil will dampen vibrations. Change your cruise rpm setting. That is all I can come up with.

[scsmith]

Thanks for your ideas Wayne,

My prop was dynamic balanced about a year ago, and nothing should have changed since then. It feels VERY smooth.

I have, in fact, lately been cruising at slightly higher RPM than I used to. Normally 2400 but have been running 2430 or so. That could conceivably hit a natural frequency of the dip stick, although one would think the problem would be more widespread.

I keep the oil at 6 qts. I add when it gets down to 5. I use a quart in about 15-20 hrs that way.

[AlexPeterson]

Mine has never broken, but it gets some abuse where it goes through the crankscase half holes near the bottom. One can see the wear marks. Wonder what kind of aluminum alloy they are supposed to be from?