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When I put the powerhead of the subject motor back together today,
there sure looks like there’s room for a top crank oil seal.
I never removed any, or else if “fell out” by itself and rolled away.I found a master parts list of sorts, for “K” model Mercs.
It shows them all having a seal, and all the same part number.A 26-21642 < (79831)
or
Sierra 18-2055, with specs of .750 shaft, 1.127 OD, .149 thicknessI dug through my seal supply, and found a CR seal that I measured with an OD
of 1.1285, which one would think would work, but when I measure the
bore of the crankcase where the seal would go, it seems to be “out of round”
and varies between 1.115 to 1.120 diameter.That seems like way too tight of a fit, and of course the crankshaft is installed now,
otherwise, machining on the OD would have been easier.Just wondering, did all these “K” models in 1941 have top crank seals?
Or may I be trying to fix something that aint broke?
Prepare to be boarded!
A while a go I went through a 1941 Neptune horizontal twin that had a
cork upper crankshaft seal. Possibly that is what was used on your Merc?
TubsIndustry standard seal part # 7415 is a physical fit for upper crankshaft seal on Early K Models. For this application there is no need to upgrade to special features which will multiply the cost without improving performance or service life.
Louis
Per seal catalog 7415 is for .750″ shaft, 1,124 O.D, & .156 thick tMercury part number cross references to 7415
Louis, I had a CR seal CR 7414 on hand, and that’s what I ended up using.
It seem to be a perfect fit once I got the crankcase bore doctored up a little.
Prepare to be boarded!
7414 is slightly thicker 0,188″ Should work OK ,but, will need to be seated slightly deeper in pocket to be flush. It would have to be touchy application for 0.032″ difference in seal thickness to affect situation. I would still go with 7415 when sourcing a seal. I have used general industrial 7415 and have tried NAPA version intended for use in automobile transmission. The shell of NAPA did not appear as robust or corrosion resistant. I believe that for the limited use a restored motor might receive that corrosion resistance is the important consideration.
so it seems to me
Louis
Louis, I have plenty of clearance above the seal with the points cam seated,
but saved your notes for “next time”. Thanks!
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