89 merc 100hp temp sensor

[springer_97011]

Im having a problem with the temp sensor alarm going off.I have replaced the water pump,checked for debrie inside the exhaust plate, and pulled the thermostat by the bypass valve.A bench test showed the sensor sloses at 185 degrees.The water coming out of the tell tale is cool and the engine feels only warm.Has anybody had a problem loke this or ideas what could cause this?Any tests to check temp of engine or componets would be appriciated.Also this motor has a pump on it.

 

[Rex]

Re: 89 merc 100hp temp sensor

IF YOU GOT A WARN ENGIN AND WATER COMING<br />OUT YOU OK.<br />WHY I DO NOT KNOW.<br />JUST AS ALONG AS YOUR PUMPING WATER<br />IT WELL BE OK.

 

[kev_79]

Re: 89 merc 100hp temp sensor

Sounds like maybe weak ground, or in the wiring. I would check the ground first, then check sensor for physical damage, then consider a new one. Good Luck

 

[springer_97011]

Re: 89 merc 100hp temp sensor

Does anybody know what temp. range this motor should be at the temp sensor under normal conditions?I ran it at full throttle abot a mile withe the temp horn going off and it seemed fine but hate to ruin a good motor.Any tests would be appriciated to test temps.

 

[kenthrussell]

Re: 89 merc 100hp temp sensor

hi had trouble with my sensor also sounds like it is closing too soon ,and beleve me i was worried too after spending many dollars for a rebuild after a overheat situation,i checked my sensor in a pot of water and a digital thermometoer a thermocouple type and it ws closing around 188 which was too close to the temp that the thermostats opened,it was also closing at odd temps so the sensor was bad inside and if your telltale water temp is fine as you can hold your hand in the stream for a few seconds as this water is hot about 180 as it is waste water, buy a new sensor.this was a merc 200 hp ,what i did and you should too is buy a new sensor only about 35 bucks well worth it and it works fine now as i have sucked up a few weeds this summer and found out...hope this helps

 

[kenthrussell]

Re: 89 merc 100hp temp sensor

oooooooops one more thing-- when you first start your engine cold watch the tell tale while it is idling and when when the motor is up to operating temp and the thermostats open you will see a definate change in water stream from cold to operating temp and this will tell you that the thermostats are fine and opening all the way...

 

[springer_97011]

Re: 89 merc 100hp temp sensor

Thanks for the info.I will replace the temp sensor beacause it was acting similar to yours.Hope it works!