Good advice, and during the mowing season when I am done with the mower for the day I always use an electric blower to remove the loose debris before storing. On newer mowers there doesn't seem to be too much of a problem with chaff build up on the cooling fins. About your experience, you mean your Bolens engine was damaged because you didn't keep the fins clean?
I always washed the mower before I put it away, and once in a while hose off the fins on the B&S
twin engine. Then in about 15 yrs it started to tap very loudly. I took it apart and the valve seat was
jumping around in its bore. Just adjacent to the valve area the fins were clogged with everything from
grass to dirt. The bore was so worn out that I couldn't keep the seat in place no matter what I tried.
I used it for another year then sold it and bought the scag. I think I did more harm just hosing it off
by pushing the debris in farther. Now I pull a few covers and use a stiff brush and air blow it clean.
Then I wash it, my wife says I'm a nut when it comes cleaning things.....cubby