1973 Johnson 25 not pumping water after impeller replaced

[CatfishMN]

Hi everyone. Just wondering if anyone has an idea of what to look for before tearing the LU back off.

I bought this motor last year and figured it was due for an impeller change this winter. So we took off the LU and replaced the impeller and water tube grommet and put everything back together.

So I started it up recently in a test tank and ran it for about 60 seconds, but observed no water spray through the bypass so I shut it down.

My question is what to look for before and after taking the LU back off? Was 60 seconds long enough to get water moving to the exhaust bypass? Should I look at replacing the thermostat? My other concern is that the setup I have for a test tank has water just covering where the LU comes together with the leg. I have seen water thru the bypass before replacing the impeller with this setup, but was wondering if this may be a problem?

Thanks for any help!

 

[kfa4303]

Re: 1973 Johnson 25 not pumping water after impeller replaced

Hi CatfishMN. For starters, make sure your test tank has enough water. Try to fill it to just an inch or two below the exhuast port, if possible. 60 seconds is more than enough time for it to start pumping water. It should do it pretty much instantly. Assuming you installed the impeller correctly, drop the lower unit and make sure that the copper water delivery tube is properly seated onto the top of the waterpump housing. I suspect that's what it is. It's actually pretty common. It can be tricky to line it up correctly when reinstalling the LU after an impeller change. You can put a bit of vaseline on the end of the tupe when you reinstall it to help it slide into the rubber gromet atop the waterpump housing. If that doesn't fix it, you may have a clogged water tube, which is also more common than you might think. To check if you're geting good flow through the copper tube first turn off the motor and remove the lower unit, then hold a garden hose to the copper tube. Turn on the water. You should see water come out of the exhaust port. If you don't the tube is probably clogged in which case you'll have to fish out whatever debris may be in there. It's easy to check the water passages in the motor too. You can remove the thermostat cover and the thermostat itself then run the motor. You should see water flowing through the motor, if not the passages themselves may be clogged, which can happen if the motor is run in saltwater often and not rinsed properly after doing so. Try these suggestions one at a time and let us know what you find. No matter what, if you seee the motor running without pumping water shut it off immediately and try a different approach. Keep us posted.

 

[sludgeguy68]

Re: 1973 Johnson 25 not pumping water after impeller replaced

The impeller also might not be engaged with the pin in the driveshaft. On my first try I didn't line things up perfectly when putting the water pump housing back on and the impeller sheared that little pin in two.

 

[kfa4303]

Re: 1973 Johnson 25 not pumping water after impeller replaced

yup. that too.

 

[CatfishMN]

Re: 1973 Johnson 25 not pumping water after impeller replaced

I'll report back with results, most likely next weekend.

I really suspect the water tube is not connected properly as it was tough to get it back together.

 

[wilde1j]

Re: 1973 Johnson 25 not pumping water after impeller replaced

a) pump not assembled correctly
b) you missed the pump outlet with the water tube
c) the grommet in the pump outlet got folded over during final assembly
d) incorrect parts used
e) pump body not well sealed to wear plate
f) pump housing or wear plate scored (if complete kit not installed)
g) pump air bleed hole plugged
h) water not deep enough for the pump to do its thing
i) debris stuck in water passages
j) stuck thermostat or vernitherm
k) key missing or incorrect
l) you went cheap and installed only an impeller, rather than a complete OEM kit
m) diverters missing or incorrectly installed
n) pump rotates clockwise looking from the top

The vanes make no difference ... if you install them incorrectly oriented, they will flip to the correct position upon rotation.

 

[RCAFMaverick]

Re: 1973 Johnson 25 not pumping water after impeller replaced

Hello all...CatfishMN....i am trying to drop the foot on my 73 65hp Johnson....I have a question for you...I removed all the bolts except 1 on the bottom, and saw a small tube running up into the linkage at the bottom of the engine, it is connected to a clamp of some sort.........my question is, do i have to remove this clamp to get the foot to fall?...if so, how hard is it to put it back together?....looks like a hell of a job, no room.....

Thx
Mav

 

[CatfishMN]

UPDATED-1973 Johnson 25 not pumping water after impeller replaced - UPDATED

UPDATED-1973 Johnson 25 not pumping water after impeller replaced - UPDATED

Hi - Update on this situation, forgot about the thread. So I took the LU back apart and everything looked fine, except when the water pump opened. Saw that the new plate under the impeller was bent. Apparently the key has slipped out and had pushed the impeller down into the plate when reattaching the LU. Put another plate on it, made damned sure the key was lined up properly, and put it back together. Pumping water again! Success!

 

[kfa4303]

Re: UPDATED-1973 Johnson 25 not pumping water after impeller replaced - UPDATED

Re: UPDATED-1973 Johnson 25 not pumping water after impeller replaced - UPDATED

RCAFMAverick, yes you need to disconnet that linkage. it's called a shift rod linkage. CatfishMN, congratulations!

 

[RCAFMaverick]

Re: UPDATED-1973 Johnson 25 not pumping water after impeller replaced - UPDATED

Re: UPDATED-1973 Johnson 25 not pumping water after impeller replaced - UPDATED

thx Kfa4303......lu is removed....put in new impeller.....question, the new impeller has straight vanes, so i curved them and forced the impeller in....that is the correct action, right?....reading in post above that if you install the vanes incorrectly (curved facing your right), they will fix themselves, is that correct ?...........1 more thing, i am trying to put lu back on and getting resistance with the last inch or so....i don't want to force it....i am thinking the gear shaft might not be in correct alignment, can i turn it a little at a time until it lines up?, or is this not an issue.........I greatly appreciate this site and all you people who help us newbie's out......

 

[wilde1j]

Re: UPDATED-1973 Johnson 25 not pumping water after impeller replaced - UPDATED

Re: UPDATED-1973 Johnson 25 not pumping water after impeller replaced - UPDATED

The vanes should be hard to get in the pump body, and yes they will flip if you get them in wrong.

You need to rotate the flywheel while raising the LU to get the splines in the driveshaft to engage the mating female splines in the crankshaft. The shift rod may also be hanging up.

 

[RCAFMaverick]

Re: UPDATED-1973 Johnson 25 not pumping water after impeller replaced - UPDATED

Re: UPDATED-1973 Johnson 25 not pumping water after impeller replaced - UPDATED

Thanks wilde1j .....all is well now....turned flywheel like you said, that was the prob....time to put muffs on and test it.