CRANK PLUG . . . What is it and do I need one? 

Topic:                               The Crank Plug (welch plug) - setting the record straight

What is it?:                       It's a plug inserted into the 60hp lower crankshaft wheel (PTO wheel to some). Factory plugs were some sort of rubber or nylon. The 50hp cranks did not have the splines broached all of the way through (blind hole) so if you're getting water in your motor, then you need to look at the lower seal, the exhaust cover seal, a cracked block, or the head gasket.

Do I need it?:                    Not necessarily. If you get water in your motor after sitting for an hour or more, then MAYBE.

Why Maybe?:                     Many times the inner-most crankshaft seal (inside the lower wheel) does a good enough job that this plug isn't needed. However, your situation might be like these:

  • If you remove and reinstall your motor like a neanderthal, then your inner crank seal is probably chewed up and in need of replacement.
  • Also, if the splines on the input shaft (on the pump) are sharp, they can damage this little seal. Take a few minutes to de-burr this thing 

Is there another solution?:  Yes - having a steel plug welded in when you have your crankshaft rebuilt

Crankshaft Rebuilding?:      Yep - contact the folks at Northern Crankshafts and they can fix you up


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