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O320 Narrow Deck Solid Crank Seal Part Number

Jermechanic

Well Known Member
Having trouble locating a SOLID crank seal for my early Lycoming o320 Narrow deck . It has the 6 screws which secure the two oil seal retaining plates .

The split seal is part number is 76940.

Iam hoping to install a solid seal but I don't see a solid seal number for this "small - no lip" type crank seal.

Has any one been down this road on one of these narrow deck lycomings?

Thanks
Jeremy


The following which is an excerpt from the Lycoming Crank seal Service Instruction No. 1324 C helps with more details but doesn't seem to list an option for a (Small) Crankshaft Oil Seal (no molded lip on outside surface)

PARTS DATA:
LW-13792 (Small) Crankshaft Oil Seal (molded lip on outside surface – solid type – three
grooves for glue retention)
LW-13792-P50 (Small) Crankshaft Oil Seal (.050 oversize Outside Diameter (o/s O.D.) for small bore
crankcases – solid type – three grooves for glue retention)
LW-11997 (Small) Crankshaft Oil Seal (molded lip on outside surface – split type)
LW-11997-P50 (Small) Crankshaft Oil Seal (.050 o/s O.D. for small bore crankcases – split type)
78443 (Large) Crankshaft Oil Seal (molded lip on outside surface – split type)
78443-P50 (Large) Crankshaft Oil Seal (.050 o/s O.D. for large bore crankcases – split type)
LW-15628 (Large) Crankshaft Oil Seal (molded lip on outside surface – solid type – three
grooves for glue retention)
LW-15628-P50 (Large) Crankshaft Oil Seal (.050 o/s O.D. for large bore crankcases – solid type –
three grooves for glue retention)
76940 (Small) Crankshaft Oil Seal (no molded lip on outside surface – split type)
74305 Crankshaft Oil Seal (two grooves for glue retention – split type)
 
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I built the narrow deck O-320 D2B engine in my flying -9A. I bought a complete gasket set from Air Power for this model and it contained both the solid and split crank seal. I used the solid seal. I seem to recall it had several small grooves on the OD to provide room for the glue you have to use. I don't have the part number.
 
76940 is the only option for my engine

I installed the split seal 76940 on my engine; according to the service manual the molded lip and the non-molded lip seals aren't interchangeable. The 13792 sure looks like it would work but Lycoming made a point of noting they aren't interchangeable so I decided to play it safe. Fingers crossed for no leaks
 
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