Kohler Generator thermosyphon

I know that Kohler used the thermosyphon cooling method, on their 4 cylinder units, up to, and including 10 kw.

I have 2 such units, one 32 volt dc 1.5 kw, and one 110 volt ac 1.5 kva.

I also have a 1956 120 volt ac, 5.0 kva, but by that time they had added a water pump.

When did Kohler stop using this cooling method, on their 5.0 and 10.0 units respectively?

I know it works fine on the 1.5 units, but, just how really effective was it, on these larger units, when they were operated for long periods, under full loads?

Did they ever build any larger thermosyphon cooled units, than 10kw?

The model T Ford was thermosyphon cooled, so at least in theory, it seems possible, that Kohler could have, if, there was a commercial demand for such a product.

Thank you for your time.

Sincerely,

Scott

Seems that the thermo-syphon cooling lost out to higher output from smaller units, IE: modernization. Sad to see it go but I can see it and use it every time I start one of my old fellas.