DT25 water flow issues

[BigBand]

We've got the mid-winter blues up north - most of our lakes now contain 'hard water'.
So, I'm looking over a buddy's 1982 DT25.

It has no tattle-tale, so I'm wondering about the cooling water.

He's freshly installed a new water pump impeller, but when we run it on muffs we don't get any water coming out the prop hub assuming that's where it should show up at.

- Is it OK to run this motor on muffs, or must it be submerged? Remember the hard water issue.
- Shouldn't we see water coming out at the hub, and maybe more water when the thermostat opens up?
- What temperature should the thermostat open at? We've used an infra-red thermometer, but shut down the motor when the head temperature reached 200 degrees.
- Does anyone have a water flow diagram for these old motors?

- Not having a tattle-tale water stream is uncomfortable. I'd like to confirm there's sufficient cooling water every time the motor is started. Has anyone added a small hose fitting to the exhaust cover with a small hose coming out of the housing? I'd sure like to add a tattle-tale to this motor.

TIA

[Solarman]

Is it possible the impeller key didn't get put back in the driveshaft? If the key is missing the impeller won't turn to pump water?
There should always be water on the impeller when it turns, either by muffs, or being submerged, water has to be above the impeller at least a couple inches.

The motor should never get that hot. Something is not right with enough water, or the pump isn't working, or a blockage.

There should be a tell tale on all outboard motors, it is possible that the tube is blocked up?

Good luck, post back on what you find out.

[BigBand]

This year and model of DT25 did not have a tell tale.

I've seen another outboard that wouldn't work with a particular shape of muff. It wouldn't pump if fed water through a rectangular muff, but did fine on a round muff. Maybe I should try that idea.

I would really like to add a tell tale. Maybe it's as simple as adding a brass fitting and a hose to the exhaust cover, like 99% of motors have.

[Moonlighter]

The small really soft round muffs often work best of all. Plenty of water pressure needed too.

[BigBand]

So, when it warms up a little (single digits the next few days) I'll try round muffs and more water pressure.

Anyone have a water flow diagram for the 1982 DT25 ?

[Solarman]

If your motor is pre- tell-tale then it should have water mixing with the exhaust coming out the midsection of the leg, where some of the exhaust comes out.
It is not a good idea to mess with the exhaust cover to add a tell-tale.
There has to be a reason the water pump is not sending water up to the powerhead to cool the motor.

If the water pump is working, you might try flushing motor with vinegar & water solution in a trash can with the solution above the level of the impeller. Adding make up solution as needed to maintain the level above the water pump. Run the same solution for 2-3 hours. Letting the motor &/or solution cool down as needed.

You can use a temp guage/ or temp gun to see if temperatures are getting too hot, and where a blockage might be.

Good luck, post back on what you find out.