'78 Johnson 25 frustrations

[Oldgenetics64]

Here's the comparison of the old and new impellers. Going to try going deeper in the water.

 

[LDUBS]

See @mirrocraft16 's comment early about putting the woodruff key back in. Make sure you don't forget that or that it doesn't fall out of place before the new impeller is seated. Assuming it has one.

For me, getting all the impeller vanes pointing the right way in the liner cup then keeping them that way while sliding the whole thing down the shaft without the key moving out of place can be kind of tricky. Doesn't help that the assembly is eccentric. But then, I'm probably just clumsy.

 

[Pappy]

Are there black marks inside your impeller cup? Will the cup come out of the plastic housing or is it mellted in there? Take a good look before installing another impeller as those blades look burned to me.

 

[thill]

As everyone else mentions, that water level in the pic is way too low, not 2-3" above the cav. plate as recommended by several people.

Depending on whether or not you greased the impeller, you may be wearing your brand new impeller down prematurely. More water!!!

 

[Oldgenetics64]

Are there black marks inside your impeller cup? Will the cup come out of the plastic housing or is it mellted in there? Take a good look before installing another impeller as those blades look burned to me.

I replaced the cap and housing because of that. There were marks and it was melted in.

 

[Pappy]

Good deal......that impeller sure looked burned. Pure lack of water will do that every time. Glad you replaced.

 

[Oldgenetics64]

But now it's looking like I need to tear it apart again. Went deeper on the water and still nothing. I'll dismount the motor so I can get a better look up inside the leg.

 

[Oldgenetics64]

As everyone else mentions, that water level in the pic is way too low, not 2-3" above the cav. plate as recommended by several people.

Depending on whether or not you greased the impeller, you may be wearing your brand new impeller down prematurely. More water!!!

I didn't even think about greasing the impeller. So looks like I'll need to get another one.

 

[LaqueRatt]

Don't feel bad. Think I managed to damage the nearly new impeller in my Merc. It's still working, but I don't know if it's working well. Inspection and likely replacement is job #1 this spring.

 

[Oldgenetics64]

This has definitely been a learning experience. I've also realized that it should be a long shaft on this tin boat instead of the short shaft.

Any suggestions on lining up the water feed tube, etc is always appreciated.

 

[AZGDOGG]

This has definitely been a learning experience. I've also realized that it should be a long shaft on this tin boat instead of the short shaft.

Any suggestions on lining up the water feed tube, etc is always appreciated.

I'll jump in and try to help with what I have learned to do. Lightly grease the driveshaft splines, do not apply grease to the top of the shaft. As a matter of fact make sure there is not a bunch of grease up inside the crankshaft and check the water tube for proper engagement into the upper seal in the power head. I sometimes tilt the engine up to more easily see inside the opening as you mate the lower unit and exhaust housing. I use one of those seats with casters and have all of my tools easily accessible at hand nearby, bright flashlight, long reach needle nose pliers, long thin screwdriver, lower unit bolts etc., whatever you think you might need to make things easier. Sometimes I use an extra long bolt or two to start and hold the lower unit in position temporarily, just long enough to hold the driveshaft in engagement while you start the water tube and start a proper retention bolt while holding the lower unit in full engagement once the water tube is started. Before you start lightly grease the water tube and seal also. Once you get it started and seated don't let it slide back out, if you do make sure the tube is engaged in the seal before reseating and tightening the lower unit bolts. I hope this helps, good luck!

 

[AZGDOGG]

I'll jump in and try to help with what I have learned to do. Lightly grease the driveshaft splines, do not apply grease to the top of the shaft. As a matter of fact make sure there is not a bunch of grease up inside the crankshaft and check the water tube for proper engagement into the upper seal in the power head. I sometimes tilt the engine up to more easily see inside the opening as you mate the lower unit and exhaust housing. I use one of those seats with casters and have all of my tools easily accessible at hand nearby, bright flashlight, long reach needle nose pliers, long thin screwdriver, lower unit bolts etc., whatever you think you might need to make things easier. Sometimes I use an extra long bolt or two to start and hold the lower unit in position temporarily, just long enough to hold the driveshaft in engagement while you start the water tube and start a proper retention bolt while holding the lower unit in full engagement once the water tube is started. Before you start lightly grease the water tube and seal also. Once you get it started and seated don't let it slide back out, if you do make sure the tube is engaged in the seal before reseating and tightening the lower unit bolts. I hope this helps, good luck!

Oh, and don't forget to engage the shift rod also!

 

[thill]

If the motor worked well before, give it a chance. Some boats, the motor looks high, but it works properly in the water.

When greasing the cup, you only need a medium thickness film, not big globs of grease. Grease the impeller well on all sides, and it helps everything go smoother.

To help align water tube, use a ratchet strap to lift/hold the lower in place, while you use a long screwdriver, wire or coat hanger to line up the tube, then ratchet the lower up until engaged. Spin the flywheel a little with tension on the ratchet strap, and the driveshaft should go in.

The ratchet strap makes life a lot easier.

Even if the impeller looks good, swap it out, and double-check the key while in there.

I hope it works out well for you.