Low operating temp

[Moody Blue]

1993 Mariner 4cyl 40hp only runs at 90-100 degree F after running at 3/4 - full throttle for 30 minutes. Have installed a temp gauge and sending unit to factory port on power head. I checked the gauge accuracy before installing on the motor. The sender is located on the head between no2 and no3 cylinders. The head temperature is mildly warm to the touch and is hotter at the top than at the bottom. The telltale stream is quite hot but I can hold my hand under it without getting burned. Is this temp normal? Can it affect plug fouling, fuel consumption etc? I thought it would have run hotter. Better too cool than too hot I guess. Is there a thermostat or other temp regulating device that I haven't found?<br />Thanks for any feedback.

 

[WillyBWright]

Re: Low operating temp

No thermostat. Water temp in a cold lake could be keeping it cool. Could also be that scale has built up in the water jacket and is insulating the area where the sender is. Surface mounted sender or screwed into the motor?

 

[Moody Blue]

Re: Low operating temp

Screwed right into the motor so that the sensor is in the water jacket. Should I be concerned or just be glad its not overheating. The water temp is about 20 C or 68 F.<br />Rod

 

[JB]

Re: Low operating temp

Moving to Mariner Troubles/Repair

 

[Moody Blue]

Re: Low operating temp

Any other thoughts on this issue ? Sure am curious.

 

[profish00]

Re: Low operating temp

install new thermastats

 

[Moody Blue]

Re: Low operating temp

Was told this unit does not have a thermostat. Can anyone confirm this ?