kahall82 Posted September 23, 2011 Share Posted September 23, 2011 Hi all,My 1982 R688RST 350 Mack is running cold. About 55 degrees celcius (131 F) all day every day, unloaded or loaded. Same with Oil Temp. But the heater is fantastic.Have noticed that there is a coolant sensor on the top of the radiator and one on top of the engine in the water pipes near the heater taps. Maybe the gauge is hooked up the the coolant sensor in the radiator and not getting hot :S And the oil temp sender may be fouled I guess as we just found it in the sump and bought a gauge to hook it up to.Replaced the thermostat for a 170 just 3 months ago due to low temps. Should I be after a 180 thermostat or is there another problem?Causing a whole heap of wet stacking :S Quote Link to comment https://www.bigmacktrucks.com/topic/20736-r688rst-running-cold-but-heater-fine/ Share on other sites More sharing options...
rhasler Posted September 24, 2011 Share Posted September 24, 2011 Sensor in the radiator should be for the Kysor low coolant level warning. Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/20736-r688rst-running-cold-but-heater-fine/#findComment-86733 Share on other sites More sharing options...
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