1956 Johnson 15 HP lower crankshaft seal

[GeneH]

Any tips on the procedure for replacing the lower crankshaft seal on a 1956 Johnson 15? I have the big Johnson manual but it is not very specific. What is the least you have to disassemble and do you have to split the crankcase. Any step by step available anywhere? I have two complete Johnsons, both electric start. Thanks for any help.

 

[HighTrim]

Re: 1956 Johnson 15 HP lower crankshaft seal

Im glad you are replacing that dreaded 303804 seal. They are notorious for self destructing, allowing water into the powerhead destroying the bearings when the oiling system distributes the water.

The hardest part is pulling the powerhead if it is a salt water motor. Other than that , an easy job really. Dont forget a new base gasket, part number 303892.

Did you already have a problem, or are you being pro active in your maintainance?

 

[GeneH]

Re: 1956 Johnson 15 HP lower crankshaft seal

I don't know that I have a problem so I may be being proactive. I haven't figured out how to tell if there is a problem. I think you know when the engine blows up! Any suggestions on where to get a step by step procedure or the parts?

 

[F_R]

Re: 1956 Johnson 15 HP lower crankshaft seal

Step by step by memory....remove the flat shifter interlock from the starboard side of the powerhead. Remove the vertical throttle shaft from the port side. Disconnect the fuel & air hoses. Remove the screwdriver slotted screws and three nuts that hold the power head on and lift it off. You will see the seal right in front of you. Easiest way to remove it is to collapse the outer shell toward the shaft and it will almost fall out. A good tool to collapse it is a cape chisel, but you probably don't have one. So grind a bevel on the end of a round pin punch. You will wind up with a rounded chisel. Carefully use it to fold the seal inward.

Use a new gasket and a new o-ring on the drive shaft when reassembling. Smear a bit of grease on the drive shaft splines.

 

[HighTrim]

Re: 1956 Johnson 15 HP lower crankshaft seal

There really isnt that much to it. Are you ok with pulling the powerhead? After that, dig the seal out carefully, and pop the new one in. It may actually fall right out when your pull the powerhead. I buy them from the dealer, part number 303804 as mentioned. Could also try one of the many online sites, Im not sure if iboats carries them but have a looksee. Here is a pic courtesy of F_R



EDIT: Frank beat me to his own pic

 

[GeneH]

Re: 1956 Johnson 15 HP lower crankshaft seal

Anybody know where to get the lower gasket 303892? The seal is readily available. Vintageoutboards.com may sell the gasket with a power head set but doesn't seem to sell it alone.