C152 Misbehaving
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Fair enough. Though I have not seen it, It is certainly possible. It might have been an 80/87 to 100LL fuel change issue, if it was anywhere in that time period.
A senior Cessna engineer, (Ceasar Gonzales, who literally wrote the book on Mogas use) told me that when Cessna itself changed over from 80/87 and 100/130 for their line fuel, some of their own brand new aircraft suffered fuel leaks, due to the higher aromatic content of the newer 100LL. Cessna had to change a whole bunch of O rings before delivering those planes. Their specified O rings were quickly changed to a more suiable composition. That new composition also survives Mogas well.
For many years the maintainers who were presented with leaking Cessnas would say "well someone's put Mogas through it, and wrecked the O rings!". Well yes, Mogas could wreck the O rings of the earlier composition, but so could 100LL, which no one was eager to broadcast. Over time, O rings get changed out anyway, so the problem fixes itself. But there are always those few aircraft with super O rings, which hang on an extra decade or two.
That said, the fuel valve O ring is the only O ring in my 1975 150, which I think might be original from new. I have not changed it in the 24 years I have owned the plane, and it works just fine, with no leaks (and I use nothing but Mogas!). As I think about it, some fuel valves had a packing other than an O ring, it could be one of those - I've never looked.
O rings are cheap, though getting at them for changing can be a job!
A senior Cessna engineer, (Ceasar Gonzales, who literally wrote the book on Mogas use) told me that when Cessna itself changed over from 80/87 and 100/130 for their line fuel, some of their own brand new aircraft suffered fuel leaks, due to the higher aromatic content of the newer 100LL. Cessna had to change a whole bunch of O rings before delivering those planes. Their specified O rings were quickly changed to a more suiable composition. That new composition also survives Mogas well.
For many years the maintainers who were presented with leaking Cessnas would say "well someone's put Mogas through it, and wrecked the O rings!". Well yes, Mogas could wreck the O rings of the earlier composition, but so could 100LL, which no one was eager to broadcast. Over time, O rings get changed out anyway, so the problem fixes itself. But there are always those few aircraft with super O rings, which hang on an extra decade or two.
That said, the fuel valve O ring is the only O ring in my 1975 150, which I think might be original from new. I have not changed it in the 24 years I have owned the plane, and it works just fine, with no leaks (and I use nothing but Mogas!). As I think about it, some fuel valves had a packing other than an O ring, it could be one of those - I've never looked.
O rings are cheap, though getting at them for changing can be a job!
Join Date: Apr 2008
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O rings are cheap, though getting at them for changing can be a job!
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