Evinrude 40hp Water Temp alarm

Redfisher44

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Feb 4, 2024
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I have a 1997 Evinrude 40hp (E40TTLECR), the water temp alarm sounds after about 5 minutes of run time. The alarm sounds for about 10-15 seconds then goes off, but the indicator light stays on. Excellent water pressure coming out of pee hole. Used thermometer to check engine temp. Shows 82 degrees. Block not hot to touch. Any suggestions on what may be causing alarm to set off as I have a good water flow from water pump and motor temp is not hot according to the touch and thermometer.
 

oldboat1

Fleet Admiral
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Apr 3, 2002
Messages
9,612
Are you testing on hose/muffs, in a tank, or on the water?
 

racerone

Supreme Mariner
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Dec 28, 2013
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37,818
Remove lower unit and inspect water pump.----Post the compression values.----Blown head gasket can cause overheating.
 

Crosbyman

Vice Admiral
Joined
Nov 5, 2006
Messages
5,440
no reason to "alarm" one woud say ... maybe bad sensor or localized hot spot.
you should be able to test the sensor itself with gradually hot water and a thermostat while checking the ohms resistance change in value compared to specs

if OK suspect the display/alarm logic .
 

ct1762@gmail.com

Master Chief Petty Officer
Joined
Jan 17, 2019
Messages
859
the overheat alarm should sound right around 200f (90c or thereabouts) so 82c is odd, especially since you say its not hot. what are you using to measure temp and where on the block? cylinder head temp is taken at flat spot on top of head at 900rpm. these will run warm if the RPM is too low, but not 82c warm thats on the verge of an all--out overheat. as racer said, check pump. very common for some dunce to pinch the water tube grommet in the water pump housing, causing it to leak over time and not provide proper water pressure. these dont have a real water tube, but still works the same way through adapter.
 

saltchuckmatt

Commander
Joined
Jul 19, 2019
Messages
2,641
the overheat alarm should sound right around 200f (90c or thereabouts) so 82c is odd, especially since you say its not hot. what are you using to measure temp and where on the block? cylinder head temp is taken at flat spot on top of head at 900rpm. these will run warm if the RPM is too low, but not 82c warm thats on the verge of an all--out overheat. as racer said, check pump. very common for some dunce to pinch the water tube grommet in the water pump housing, causing it to leak over time and not provide proper water pressure. these dont have a real water tube, but still works the same way through adapter.
Poster said "82F"
 
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