68 Mercury 110 9.8 - Should water exit exhaust when hose attached to water pump pipe?

[crankybrit]

Hello, I’m new here and looking for sole help.

I just replaced the water pump impeller and associated parts and initial test with motor running in barrel failed to show tell tale water.

Possible I did not submerge the LU far enough this time…

I just removed the LU and attached hose to copper pipe to test end to end water flow. Removed flush. Water comes out of flush and tell tail just fine. Should it not come out of exhaust as well? If so, I guess it means a blockage in the engine?

 

[racerone]

Fact for you.-----Perhaps if this motor was severely overheated ( happens a lot ) because owners did not install new impeller every 3 years.------There is a plastic washer at the top of the water tube.----It melts on severe overheat.----Blocks water flow.-----Powerhead needs to be removed for inspection.-----Simple job for me.---Replacement factory part is better Quality.-----They now know this was an issue.--And in a test tank water MUST be 6" ABOVE the impeller.----A compression test should be done , post your numbers.

 

[crankybrit]

Thanks for your help. I was also thinking that there may be a thermostat that would be closed at the engine (when cold) and therefore no water coming through the exhaust in my test. The motor does start and run fine for short tests which I have done a couple of times. I did notice a white plastic washer fell out or come off the copper tube when I disassembled the first time. I never did figure where that was meant to go. I will test again with 6in water min and see what I find. For compression test, you me through spark plug at cylinder head?

 

[racerone]

There is no thermostat !----Compression test is done through the sparkplug hole.-----And there is no " cylinder head " on that motor.

 

[crankybrit]

OK. Makes sense, thanks for your help as I'm learning about marine engines and this is my first. Still curious whether water blown up from the LU should exit via the exhaust as well as the tell tail? Seemed to me like a decent test for any blockages.

 

[racerone]

Water that is pumped to the powerhead must be returned to the lake !

 

[crankybrit]

That makes sense, I was trying to understand the path the water takes back to the lake so to speak

I was figuring if I could blow water up into the engine, I can confirm the tell tail is working (it is) and then wherever the water goes to leave the engine and back to the lake.

My limited understanding was it comes out the same place as the exhaust, so I was thinking I should see my water from the hose exit there as well. At that point I can confirm there are no blockages and all I need to do is make sure the water pump is working correctly. Maybe the tell tail is the only way the water exits the engine? In that case I think this part is working fine. Sorry for the dumb questions.

 

[racerone]

Nope----Most of the cooling water goes out with the exhaust.----End of the story.

 

[crankybrit]

Nope----Most of the cooling water goes out with the exhaust.----End of the story.

I just reassembled and ran the motor in deep can of water. It ran well and plenty of water out the tell tail. Slightly warmer than it went in. Engine body stayed nice and cool so I think everything is working. Thanks for your help.