Thermostat question

Keithtalik

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Jun 22, 2016
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10
I own a 2011 Yamaha 50
Im having an issue with my motor over heating after changing the water pump out. Boat ran fine for an hour until i started idling. I checked the thermostat to see if it was bad. (Tested it, it works in boiling water..) The hole the thermostat came out of was dry. Shouldn't there be water coming out of this hole when motors running..
I have water coming out the pee hole with good pressure . Lower end seems fine. I feel like I'm not getting water to the top half.. Any ideas/thoughts?
 
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Keithtalik

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Jun 22, 2016
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Ok it does appear water is passing through the thermostat area. It appears water is passing through the lower and upper unit but for some reason its not cooling the motor ...... so confused
 

flyingscott

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Apr 8, 2014
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Did the old water pump work correctly before it was removed. If it did when you put it back together did you make sure the tube was lined up correctly to the waterump housing.
 
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Keithtalik

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Jun 22, 2016
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No, the old pump was shot and sounded the alarms thats why i changed it in the first place. I double checked everything and it appears to be put back together right.. I flushed everything, blew out the lines, getting good water pressure from the pee hole.. When i start the motor (in a barrel of water) it takes about 2 mins and the water coming out the tell tale is scalding hot, same with the motor.. Immediately pulled the thermostat to find it wide open... (definitely appeared to be working).
 

oldboat1

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Apr 3, 2002
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not a Yammi guy, but I would pull off the lower unit again and take out the thermostat. Try to flush from the bottom up the tube, and down from the t.stat opening. See if (and where) water exits. You may need to pull the head cover and maybe exhaust cover to find blockages.
 
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