77 Johnson 35HP water pump replacement

[Jeff74]

Hello All,

I have the new water pump kit to for my Johnson 35. This is my first time to replace one myself. The only way I can get the impeller to fit into the housing is to really twist and force it in there. Is this normal, or did they send me the wrong impeller and/or housing? Thanks-Jeff.

 

[tashasdaddy]

Re: 77 Johnson 35HP water pump replacement

use a little liquid soap, suppose to be tight.

 

[JDSmith]

Re: 77 Johnson 35HP water pump replacement

On my 74 70hp it was a very tight fit. The blades of the impeller have to be bent to fit in, that is normal. Make sure you bend them the RIGHT way though. I just looked at how my old ones were bent to know.

If you actually read the Johnson shop manual it explains how those impellers work. Something about the pump behaves as a displacement pump at low speed but at high speed the blades actually will curve due to the force of the water and the pump will become a centrifugal pump. Of course they didnt explain why it has to pump one way the one time and another way at high rpm's.

My instructions talk about putting a little light-weight oil in the housing as well.

If you have a woodruff key make sure it does NOT slip out when you lower the housing. I made that mistake and could tell I wasn't getting any pumping. I had to take it all apart again and it took me 7 tries to keep the key in place while lowering the housing down.

Good luck getting the impeller in there, it was a hand killer for me.

 

[HighTrim]

Re: 77 Johnson 35HP water pump replacement

Oil the blades as stated. When lowering the impeller housing, turn the drive shaft clockwise while doing so. Dip screws in gasket sealing compound. Be careful when installing the lu, the water line can easily knock the rubber grommet on top of the impeller housing off, blocking water flow causing your motor to overheat. Grease the splines of the drive shaft as well before putting it back up. Also be sure not to adjust the shift rod, the tolerances are tight.

 

[Jeff74]

Re: 77 Johnson 35HP water pump replacement

Thanks, everyone for the info. Hopefully, this will go well. -Jeff.