Tell tale peeing well but nothing coming out of exhaust housing on Johnson 1979 15hp

[snapper1]

Could someone please guide me on how water flows in 1979 Johnson 15hp? Have taken leg off and ran a hose up the copper tube and there is good flow coming out of the back tell tale and that increases when I turn the hose up. However, nothing at all comes down the exhaust housing. It only exits through tell tale.
I seem to have a problem and not sure where to look. Thanks

 

[Roadking57]

If you are using muffs with a garden hose, find a bucket and run it. May start flowing from there that way. Not sure if you are running the engine from re-reading your post. You should have a thermostat that may not be opening or hasn't reached operating temp.

 

[racerone]

Thermostat has nothing to do with tell tale.----Water comes out of tell tale 3 seconds after starting.

 

[Roadking57]

what about exiting thru the exhaust housing?

 

[racerone]

There might be a blockage.----Old impeller pieces ??----Can't tell without seeing this motor or knowing history of what prompted this investigation !!

 

[snapper1]

Hi, I got it recently and have not run it as was sitting around for a few years. I took lower unit off to inspect water pump and only the impeller vanes were quite bent but no deterioration of rubber. I then thought to check the water passage into the motor by hooking a hose to the copper water tube. I've done this on other motors and water comes out of the exhaust housing body as well as the tell tale. However with this motor the water only expels from the tell tale. Nowhere else.
Hope that clarifies my question.

 

[racerone]

There likely is a blockage.-----Tell tale water comes off the exhaust housing and does NOT circulate through the engine.

 

[kbait]

When thermo is closed, no (or very little) water exits exhaust housing. Also, running on muffs doesn’t test waterpump function. Test in barrel or lake, and when head temp warms to 140ish, thermo opens and water exits powerhead.. most of that water exits with exhaust through prop, and some gets blown out of exhaust relief port(s). Install new impeller and test in water.. you’re likely all good

 

[snapper1]

Thank you Racerone for your help. I thought it was odd. The tell tale stream just got stronger as I increased water pressure going up copper tube with nothing else happening.
Could a blocked thermostat in the cylinder head water cover do that?

 

[kbait]

See post 8. Your test is producing expected result..

 

[snapper1]

When thermo is closed, no (or very little) water exits exhaust housing. Also, running on muffs doesn’t test waterpump function. Test in barrel or lake, and when head temp warms to 140ish, thermo opens and water exits powerhead.. most of that water exits with exhaust through prop, and some gets blown out of exhaust relief port(s).

Thank you too kbait. I used a water hose only to the copper tube without starting and on 2 other motors I have tested this way, water still expelled from both the exhaust housing and tell tale

 

[racerone]

Install a new impeller.----Test run in the lake.------Thermostats often fail in the OPEN position .----So check and make sure motor warms up.

 

[kbait]

Pre-telltale motors have a small bypass in thermo housing so water always comes out ‘blubber’ hole, acting as telltale. So your test would show water exiting exhaust chamber on those..

 

[snapper1]

Install a new impeller.----Test run in the lake.------Thermostats often fail in the OPEN position .----So check and make sure motor warms up.

Will do and will monitor how hot it gets.
If the thermostat has failed in the open position, shouldn't the water have still expelled from the exhaust housing too?

 

[kbait]

If the thermostat has failed in the open position, shouldn't the water have still expelled from the exhaust housing too?

yes

 

[snapper1]

Pre-telltale motors have a small bypass in thermo housing so water always comes out ‘blubber’ hole, acting as telltale. So your test would show water exiting exhaust chamber on those..

This is a 1979 model and has a dedicated tell tale.

 

[racerone]

Stop guessing.-----Install a new impeller.-----Test run in the lake.-----Monitor engine temperature for 15 minutes !!

 

[snapper1]

If the thermostat has failed in the open position, shouldn't the water have still expelled from the exhaust housing too?

yes

Then hopefully it is a working thermostat that is in the closed position. Would it be best to take water cover off and inspect and test thermo first?

 

[snapper1]

Stop guessing.-----Install a new impeller.-----Test run in the lake.-----Monitor engine temperature for 15 minutes !!

Sure, many thanks for guiding me Racerone

 

[racerone]

Do what you like , have time for.