Best method to test water pump - no tell-tale

[DWM76]

Hi all,

I have been working on the old 68 Johnson 55hp (TRL-10R) and recently rebuilt the water pump. Being an outboard newbie I am not sure of the best method to verify it is working as there is no tell-tall and I believe water exhausts via the prop so with the lower unit in a barrel I'm not seeing flow.

At this time I am not supplying charge to the ignition system or any fuel, just turning the flywheel with the starter. (short bursts like testing compression)

1) Can I remove the thermostat and cover to check for flow to the water jacket?
2) How much of the lower unit needs to be submerged for the pump to move water?
3) I keep finding missing pieces - no trim tab...would this effect the pump function?
4) Should I remove the l/u and test by manually turning the drive shaft when submerged?

I feel like these are really dumb questions so I apologize for having to ask them.

I tried to check for flow once with the l/u submerged up to an inch above the intake screens, with the thermostat cover off and thermostat removed. No flow.
Driveshaft is turning prop shaft. Pretty sure intake and return water tubes are correct, they are visibly different.

Thanks,

 

[F_R]

You got things backward. Get it running, then worry about the water.

1.) Waste of time.
2.) Pump needs to be submerged
3.) Trim tab won't keep it from pumping
4.) Won't prove a thing if you do. There is no exhaust around the pump while you are doing that---or any possible restrictions

When the motor is running, the whole exhaust housing fills up with water, surrounding the inner exhaust tube. That is a lot of water it needs before some of it spills out the two exhaust relief holes in the rear. Trying to fill it with the starter is futile.

Once you get it running, the water spilling out the exhaust relief holes is your "tell-tale".

No such thing as dumb questions. Refusal to follow advice, well......... some people actually do that.

 

[racerone]

Water MUST be 6" above the pomp.----Just covering the intake screen is simply not the proper way to test this motor !!-----

 

[oldboat1]

Alluded to compression testing in your post -- did you test it? Crank until the needle stops moving, and note the reading (all three plugs removed). Keep the l.u. submerged so you don't damage the new impeller (For barrel testing, my rule of thumb for water depth is about half way up the shaft). When testing for spark, use an adjustable open-air tester.

Maybe you are already beyond this.

 

[DWM76]

Thanks for the advice. I will be following it no doubt. I did test the compression but did that wrong as well. Thanks to advice here I tested again... properly. The psi was within 5 for all 3 but low, around 80. Manual says minimum 100 so some troubleshooting to go there yet.
Still waiting on a coil before I can test spark and ignition.

Thanks again.

 

[oldboat1]

might try another tester -- maybe borrowed from an auto parts store. (No need to open the throttle on your 2-cycle, btw.) Also might squirt a bit of WD-40 in the cylinders and check again.