1969 Evinrude 4HP (Model 4906B) - water pump housing removal & impeller kit options

[Good Trout To You Sir]

1969 Evinrude 4HP (Model 4906B) - water pump housing removal & impeller kit options

Stuck on land until I complete this "simple" water pump service. Metal pump housing held to base with 2 screws. Screws are out, but housing firmly stuck in place (even after rubber mallet used). No idea what's holding it. Does housing twist into/out of position when seating against base plate? Can pump be modernized? Repair kit P/N 379763 is unavailable and Sierra equivalent seems to lack water tube grommet, screws, and impeller key. Grateful for your advice.

 

[F_R]

Corrosion between the OD of the pump housing and ID of gearcase cavity is the only thing holding it. A pry with a screwdriver should lift it out. Just don't go nuts with the screwdriver and bust something.

Needless to say, clean all that mess up before re-assembling it.

 

[Good Trout To You Sir]

Thanks, F_R. Which pump repair kit do you recommend?

 

[racerone]

Fact ---Corrosion can hold these.-----That pump housing also lines up the lower unit / exhaust housing / driveshaft and crankshaft splines.----Therefor it is a close fit.

 

[Good Trout To You Sir]

Corrosion between the OD of the pump housing and ID of gearcase cavity is the only thing holding it. A pry with a screwdriver should lift it out. Just don't go nuts with the screwdriver and bust something.

Needless to say, clean all that mess up before re-assembling it.

Have managed to remove metal housing and base plate from lower unit. Wow - talk about scale build up! Used CLR to remove most scale. Pictures attached for perspective on degree of corrosion. After clean up, pump housing mating surface has a couple areas close to completely smooth, but not quite. Want a proper seal of metal housing to replacement base plate of new water pump. Before I use sandpaper, gasket maker or gasket sealer I should ask: Any suggestions on how to condition metal pump housing mating surface or otherwise achieve a secure seal through mechanical or chemical means?
Gear oil looks good - no obvious sign of water intrusion. From oil seal photo, can anyone suggest what signs to look for re: necessary replacement of this seal just underneath the pump base plate? Unclear to me if it's supposed to spin in place.

 

[racerone]

The driveshaft spins.---The seal does not spin.

 

[Good Trout To You Sir]

That's good --- because the outer edge of the seal is firmly cemented into the casting.
Are there physical markers on these oil seals or the drive shaft that would indicate wear/failure?

 

[F_R]

From what I can see from the photo, the seal looks ok. Good photo, BTW.

You need to clean up the surface below the pump plate and use some kind of gasket sealer between the plate and gearcase. Nothing needed between plate and pump housing, other than clean surfaces.

 

[Good Trout To You Sir]

You need to clean up the surface below the pump plate and use some kind of gasket sealer between the plate and gearcase. Nothing needed between plate and pump housing, other than clean surfaces.

F_R & racerone: Thanks in large part to your advice, I now have a strong water pump installed in this Lightwin. I was aghast at the degree of scale that sealed the metal pump housing to the lower unit --- despite no signs of saltwater use. Next task is to troubleshoot a stubborn & unsafe carb flooding problem. Topic of forthcoming new thread. I hope you will take a moment to read and comment on next steps. Thanks a million for your help!

 

[Crosbyman]

Johnson

fyi...a carb is like a toilet bowl ..if it floods the float/inlet needle need adjustment