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Impeller & water pump question 1990 15 hp

S

shimanok2

Member
Hi all, I'm new to the forums as I just picked up a 1990 15hp short shaft. It starts and runs great, however isn't peeing water from the outlet port. I've just got a few questions I hope you all can answer.

I dropped the lower unit to remove the water pump and everything seemed fine. The impeller however does not have straight blades as it apparently should judging by the pictures of a replacement impeller. Also, the axis of the driveshaft, and thus the impeller, are not concentric with the inside face of the impeller housing. That is, if the impeller is placed in the housing,the axis of it and where the dirveshaft would be do not line up. Is this normal? a defective housing?

Additionally, to check for blockages I took out the thermostat and forced air into the cavity. Air can be felt coming out the outlet (peeing) port and the tube that slides into the water pump housing. I can see the water intakes on the lower unit as well, so I know the blockage isn't there. Any other thoughts on a blockage?

Any help would be greatly appreciated. Thanks a lot.
 
Re: Impeller & water pump question

The geometry of the drive shaft and the impeller housing is correct. It is off set. Install a new impeller clear the pee hole and run her.
 
Re: Impeller & water pump question

I purchased a new johnson/evinrude impeller for a 1990 15hp and when I got home I realized that the diameter of it is much larger than the inside face of the water pump housing. Is it suppose to be this tight of a fit that the impeller blades bend over (see photo below) or am I just missing something? Could it be an older lower unit that requires a smaller impeller? Attached is a photo with the new impeller, old impeller and housing. Thanks for the help.

impeller1a.JPG
 
Re: Impeller & water pump question

It is supposed to be larger. Put some lube on the impeller and force it into the housing by rotating it in the direction of the drive shaft.
 
Re: Impeller & water pump question

I installed the impeller only to realize that the upper shift linkage bolt is somewhat stripped. I'll replace that this afternoon, put it all back together and test it out. On another subject, should there be any sealant between the lower unit and the exhaust housing, or just metal on metal? Thanks again.
 
Re: Impeller & water pump question

I installed the new impeller, put the lower unit back on and tested it out in a bucket. Water started shooting out immediately. I would have though the stream would have been more intense, but I suppose not at idle. It definitely was a stream though and not a dribble. I even pulled off the thermostat after I let it run for a several minutes and there were water droplets hanging out inside, so I'm guessing water is getting up there as well. The block never got too hot either. Things are lookin up!

Thanks for all the help Docksidemarineservices!!!
 
Re: Impeller & water pump question

Again, thank you very much. Unfortunately, another problem has arisen. After running the motor to test the water pump, I took it out of the tank, let it dry off and put it back in my basement on a sawhorse. I went back a few minutes ago and noticed very dark drops of oil (i'm guessing gear oil) on the ground directly beneath the prop.

A) Would this be the seal directly behind the prop?

B) should I start a new thread for a new topic?

Thanks again
 
Re: Impeller & water pump question

If the drops are the same color as the gearlube, a gearcase leak may exist. However, if the drops are very black in color, it is no doubt simply the excess fuel mixture draining down thru the long soot lined exxhaust housing..... a very common problem on the 9.9 and 15hp models.
 
Re: Impeller & water pump question

I'm not sure what color the gear lube is as I just acquired the motor a few days ago and haven't checked that out yet. I'm guessing a gear lube change would dismiss this concern. Thanks a lot.
 
Re: Impeller & water pump question

Just loosen the bottom large slotted drain screw to allow a small amount seep out to either give you peace of mind........ or :)
 
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