So I spent this afternoon rebuilding the lifters on 3 of my kohler 25s mainly because of oil additives.
I be the first to say I put oil and fuel additives in all my engines and always have . I’m a believer that they extend engine life. Unfortunately one of my 3 kohler were making a terrible tapping and it was hard to start when warm.
After checking valve Clearence it was obvious there was an issue. There was no clearence at all and the valve were not closing.
Kohlers run hydraulic lifters so there is no adjustment.
Long story short the oil additives were to thick to let the lifters work correctly.
Just for caution I went ahead and rebuild the lifters all three engines.
The lesson -Always use what the manufacturer recommends even if you think you know better.
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I generally do this for warranty.
