Kohler points plunger

T.R.K. · Apr 10, 2020

I just got a rebuild kit for a K301 Kohler from Ebay. The seller states that if you have an aluminum points plunger you are supposed to replace the aluminum points plunger with a different one, perhaps a steel one. The one in my engine is the aluminum one. The seller states that an aluminum plunger will advance the timing and the engine will die from detonation.

Now this leads me to believe that the aluminum points plunger wears and closes the points, causing them to open earlier and the timing to advance.

Does anyone know what the measured length of a new points plunger for a K301 is supposed to be?

gab · Apr 10, 2020

I don't think that's anything new, parts guy where I used to get parts 25 years ago told me to replace them.

MNGB · Apr 10, 2020

I don't think that is right Yes the aluminum one wears and should be replaced but as the alum one wears it gets shorter that would cause the points to open late retarding spark / closing the point gap
GB in MN

mikeb789 · Apr 11, 2020

I've got a Kohler KT17 twin torn apart right now (which has sat for 10 years in a damp basement). The aluminum breaker point shaft had a build up of white corrosion on the top end. Bottom end of plunger still had oil on it and was perfect. I rubbed down the corrosion using super fine sand paper. So shaft had grown.

catalina0029 · Apr 11, 2020

I would have to think it would take a very long time for the plunger to wear that much.

Steve A W · Apr 11, 2020

Does it expand the length when it heats up?

DMartin9N-2N · Apr 11, 2020

Good evening, Steve A W: I can't find a table showing how much metals expand when heated; somewhere there are tables for such things. I feel safe in saying it would be very slight (like a small percentage) and would be small enough to not affect timing noticeably. Also, the engine parts would be exposed to the same heating, so that would cancel out the effect; i.e., the parts would all grow at a similar rate. Just my opinion,,,

Dennis M. in W. Tenn.

DR. EVIL · Apr 12, 2020

Aluminum expands more than steel for a given tempurature increase, but WAY down low on the block close to the oil in the oil pan I would be surprised the points pushrod ever exceeds 200 deg F.
EVERY time you set the points gap you are adjusting for ANY wear the rod may have suffered. I have heard the eccentric the push rod runs on can wear and not give the points enough gap. Didn't happen on any of my engines, but somebody claims it happened to him.
I did replace the points pushrod on my old K241 last time I rebuilt it. The old one was fine, but I removed the engine from my Cub Cadet 72 to install my fresh K321, and SON took the K241 apart. It got moved from place to place 5-6 times before I had the machine work done and got the parts to rebuild it, the pushrod and the red valve in the crankcase breather ended up missing, but the gasket kit had a new red valve. That pushrod was ELEVEN DOLLARS!

Kohler points plunger

T.R.K.

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gab

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MNGB

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mikeb789

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catalina0029

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Steve A W

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DMartin9N-2N

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DR. EVIL

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