Kent
Bronze Member
Due to previous engine problems with Robin rockers self-loosening, I added checking them as part of my 50 hour service to my new engine. As it turns out one was indeed a little wide, so I brought it to spec and replaced the rocker covers using new paper gaskets.
Everything back together and a quick warm up to check for any leaks (also did the engine oil/filter change), I headed out to do an hour of field mowing. What a mess, mowing down tall grass and a billion foot tall dandelions going to seed. The engine was hot, but kept going strong. But as I went into the other field the engine started to sputter and backfire, and eventually stopped running. Of course the flywheel fan, hydraulic radiator, and air filter were all caked with dandelion seeds, so I brushed those all off. The engine started, but wouldn't get up to speed and kept coughing. So I limped back to the garage for further inspection and diagnosis.
What I found was a layer of finely sprayed oil everywhere in the back of the tub, on the rear of the engine, and on the heat shield (all covered with white dandelion seeds pods, of course) so I went about looking for the source of the oil. And I also popped off the valve covers to see if one of the rockers came loose, which would explain the backfiring. Well wouldn't you know, on the fan side of the engine, the bottom edge of the rocker cover paper gasket had twisted a little when I checked the valves before, enough to let oil leak past. The side fan had became a nice turbo blower, misting everything with oil, and coating the oil with dandelion seeds. Messy, and lucky it all didn't catch fire! Everything back together, new paper gaskets, and degreased with some orange oil and light pressure washing.
Started up the engine, but still sputtering and stalling. Crap. Did I burn a valve? Before panic set in, a little rethinking of the whole chain of events caused me to rethink the air filter as a possible cause. Even though only a few dandelion seeds had been stuck on the foam and the filter wasn't that old, I did find a light misting of oil underneath the filter. If oil made it under the filter, then oil must also be plugging up the paper element, causing extra gas in the intake manifolds to explode due to the engine being really hot. I cleaned up the oil mist and popped on a new air filter, and shazam, it started right up and is back up to full power!
Moral of the story? If you have a side fan, always have a new air filter on hand.
Everything back together and a quick warm up to check for any leaks (also did the engine oil/filter change), I headed out to do an hour of field mowing. What a mess, mowing down tall grass and a billion foot tall dandelions going to seed. The engine was hot, but kept going strong. But as I went into the other field the engine started to sputter and backfire, and eventually stopped running. Of course the flywheel fan, hydraulic radiator, and air filter were all caked with dandelion seeds, so I brushed those all off. The engine started, but wouldn't get up to speed and kept coughing. So I limped back to the garage for further inspection and diagnosis.
What I found was a layer of finely sprayed oil everywhere in the back of the tub, on the rear of the engine, and on the heat shield (all covered with white dandelion seeds pods, of course) so I went about looking for the source of the oil. And I also popped off the valve covers to see if one of the rockers came loose, which would explain the backfiring. Well wouldn't you know, on the fan side of the engine, the bottom edge of the rocker cover paper gasket had twisted a little when I checked the valves before, enough to let oil leak past. The side fan had became a nice turbo blower, misting everything with oil, and coating the oil with dandelion seeds. Messy, and lucky it all didn't catch fire! Everything back together, new paper gaskets, and degreased with some orange oil and light pressure washing.
Started up the engine, but still sputtering and stalling. Crap. Did I burn a valve? Before panic set in, a little rethinking of the whole chain of events caused me to rethink the air filter as a possible cause. Even though only a few dandelion seeds had been stuck on the foam and the filter wasn't that old, I did find a light misting of oil underneath the filter. If oil made it under the filter, then oil must also be plugging up the paper element, causing extra gas in the intake manifolds to explode due to the engine being really hot. I cleaned up the oil mist and popped on a new air filter, and shazam, it started right up and is back up to full power!
Moral of the story? If you have a side fan, always have a new air filter on hand.
