This seal is much easier to install than the doughnut seal. It has a larger rib that snaps into the seal groove and appears to be a better design with the spring molded into the seal...no spring to connect in an almost impossible area to access! The spring in this seal expands to clamp the inner diameter around the crankshaft and pushes the outer diameter into the seal boss. I installed the doughnut seal a year ago and it started leaking so decided to give this seal a shot. Engine power run on the ground with no leaks so far. I believe the doughnut seal is so hard to install that it is less likely we get a good result. Problems with either seal is likely due to installation errors. Follow Lycoming Service Instruction SI1324D meticulously!

Split seal did not hold. Get the non split seal.

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Superior SL11997 Crankshaft Sl For Lyc