At coolant temperatures below approximately 86 – 89 ° C (186 – 193 ° F) for vehicle, industrial, and keel-cooled marine engines or 69 – 73 ° C (156 – 163 ° F) for heat exchanger-cooled marine engines, the thermostat valves remain closed and block the flow of coolant from the engine to the radiator or heat exchanger. During this period, all of the coolant in the system is recirculated through the engine and is directed back to the suction side of the water pump via a bypass tube. As the coolant temperature rises above 86 – 89 ° C (186 – 193 ° F) for vehicle, industrial, and keel-cooled marine engines or 69 — 73 ° C (156 — 163 ° F) for heat exchanger-cooled marine engines, the thermostat valves start to open, restricting the bypass system, and allowing a portion of the coolant to circulate through the radiator or heat exchanger. When the coolant temperature reaches approximately 97 ° C (207 ° F) (or 82 ° C [179 ° F] for heat exchanger-cooled marine engines), the thermostat valves are fully open, the bypass system is blocked off, and the coolant is directed through the radiator or heat exchanger.
Properly operating thermostats are essential for efficient operation of the engine. If the engine operating temperature deviates from the normal range of 86 – 99 ° C (186-210 ° F) (or 69 – 82 ° C [156 — 179 ° F] for heat exchanger-cooled marine engines), inspect and replace the thermostats, if necessary.
| 1. Oil Cooler Housing | 5. Water Bypass Tube |
| 2. Thermostat Housing | 6. Water Pump |
| 3. Vent Line Outlet | 7. Water Inlet |
| 4. Water Outlet (To Radiator) | |
Is there anyway I can get a layout of the whole engine?
water wont circulate ..new heater core new radiator new water pump,,,,and thurmastates,,,,it just flows a 1/4 of a line i have a clear line on water pump to watch water flow,,,the heat comes and goes,,,ck alll swing doos and vavles for being obstruted,,dont know w hat elsa to try and ideas
Hi Jim,sounds like you may have air in the system or getting air in the system.Have you purged air from system from highest point?Usually a draincock in top hard-line(from radiator to thermostat housing)Headgasket?Air compressor may be pushing air into cooling system!Clear temporary hoses are a big help in troubleshooting.Is your engine fan running all the time?Even if the solenoid (electric over air)switch is not supplying enough air,fan could be dragging enough to cause problems.What temps are the engine running?Are you able to remove cap?Does it seem pressurised?Just some thoughts.Truck mechanic since the eighties,turned driver in 2016,owner-op.First truck 2001 Century 12.7 Detroit.Current truck-98 Classic,12.7 Detroit.Good luck to you,Scott.
Jim,one more thought,did you replace seals in thermostat housings,while you were in there?Scott.
You have to take out the thermostat from the housing and place a heart in it to know if it actually open and close to the right heat time