Evinrude 1979 35HP replace impeller question

[Lewis]

I'm replacing the impeller on a 1979 Evinrude 35HP long shaft that I recently picked up. Model 35903A, serial number E002229. I've got some photos below. The impeller that I took out is the one in the cup with the round pin. The one that got to replace it is the one with the ridge and the wedge. The last photo is the shaft, showing the flat at the base where the impeller sits. Is the one with the ridge and the wedge correct, and the original owner had an incorrect one? If so, how do the ridge and the wedge and the flat spot on the shaft fit together?
Thanks!
Lewis

 

[jasper60103]

The Mfr changed the design to use a wedge pin. Both will work.

 

[Lewis]

Thanks! Does it matter which direction the wedge goes in?

 

[Lewis]

deleting double response

 

[Lewis]

OK., I got it. Pretty clear how it fits once you slide the impeller down to the flat part of the shaft.
Thanks again!

 

[Lewis]

OK, I got the new impeller in, but still no stream. I do have a lot of water coming out the thru the prop wen the muffs are on and the water running in. I stopped the engine, then I ran water directly into the block from the top (disconnected the pee tube and ran water thru it the opposite way). When I did that, the water runs out thru the prop, and not out the water intakes where the muffs are connected. Any ideas?

 

[jasper60103]

OK, I got the new impeller in, but still no stream. I do have a lot of water coming out the thru the prop wen the muffs are on and the water running in. I stopped the engine, then I ran water directly into the block from the top (disconnected the pee tube and ran water thru it the opposite way). When I did that, the water runs out thru the prop, and not out the water intakes where the muffs are connected. Any ideas?

Sometimes by dropping the gear case again, you correct the problem. Also, I like the water pump test...Goodluck.
https://www.youtube.com/watch?v=xAJfBKNs7bo

 

[Lewis]

Thanks! It pumps for a while if I prime it by running water in the pee hole while the motor is running, but after 10 seconds or so, it stops. Which makes me think that the pump is not able to draw water. I can't tell from the parts diagram or the manual exactly how water gets from the intakes to the pump. This motor has been sitting for a long time, and there was some mouse nest stuff in it, so it's possible that it is clogged up down there. How would I go about checking, and where would I look?

 

[hardwater fisherman]

When testing water pump I would suggest using a tub or barrel and not muffs.

 

[Lewis]

Thanks I tried the idea in the video that Jasper suggested, but the shaft is too big to chuck in a drill very well. I also tried it in a tub, and it worked one time, but the next time I tried, it didn't pee. After that is wen i tried priming from the top.

 

[biggjimm]

Make sure there isn't any obstruction in the tell tale hose & fittings. Mine kept getting pieces of rubber from the extremely deteriorated impeller clogging up the elbow where the hoses attaches to the motor. I had to use a drill bit to get the junk out of the fitting it was so packed in there. Good luck. Jim.

 

[Lewis]

Thanks, Jim. That doesn't seem to be the issue here; I get water flowing well in both directions. I guess I'll drop the gearcase again and take the pump apart again to see where the pump intake is.

 

[Sirrobin53]

Did you paint the LU? Check the screen for obstruction.

 

[Lewis]

I haven't painted the lower unit, and it looks like factory paint. The intakes are clear. I just need to see how the water is supposed to get to the base of the pump from the intakes. The parts diagram shows an intake screen that appears to drop in from the top of the gearcase towards the front. I'll take a look at that.

 

[racerone]

????------Water MUST be about 6" above the pump itself for any testing !!!--------These pumps are NOT self priming.--------Just covering the intake screen is not good enuff.

 

[Lewis]

Racerone, many thanks! I rigged up a deeper tub, and get a strong, steady telltale stream.
But that raises another question: I have a couple of other outboards (a '98 25HP Evinrude and a '94 60HP Merc) that I regularly run on muffs with no issues, so why the struggle with this one?

 

[Sirrobin53]

Did you try muffs again after the barrel? We have small wasps that go in the screen and make nests. I had the same tell tail problem and after the barrel the muffs worked fine.

 

[racerone]

Pressurized water holds a lot of air--------Some systems are better able to get rid of this air.

 

[Lewis]

sirrobin,
I have not gone back to the muffs. The motor is for a project boat that needs a lot of work. I won't be using the motor until September, so it is essentially in storage for now.
Racerone,
That makes sense.
Thanks to all who helped!