What Causes the Motorcycle's Expansion Tank Not to Get Hot?
4 Answers
The reasons why the motorcycle's expansion tank does not get hot include a damaged thermostat, faulty temperature gauge or temperature sensor, and clogged water passages. Damaged Thermostat: A damaged thermostat causes the vehicle to remain in a large circulation loop. You can check this by opening the radiator cap when the engine is cold and observing the circulation speed. If it's fast, the thermostat is likely faulty. Faulty Temperature Gauge or Temperature Sensor: The simplest way to diagnose this is by using a thermometer to compare the actual coolant temperature with the reading on the temperature gauge. Clogged Water Passages: This prevents water from circulating, leading to engine overheating. Immediate repair is necessary, as prolonged operation at high temperatures can cause significant damage to the engine.
I've been working with motorcycles for many years and found that when the auxiliary tank isn't hot, it usually indicates a problem with the cooling system. The main causes could be insufficient coolant or a leak, where the fluid level is too low to circulate properly; it might also be a stuck thermostat preventing fluid flow; or a faulty water pump or air bubbles in the system blocking heat transfer. Normally, when the engine starts and heats up, the fluid expands and flows into the auxiliary tank, which should then become warm. If it remains cool, you should immediately check the fluid level and pipes to avoid engine overheating and major repairs. Regular maintenance, including periodic coolant changes and checking the system's seals, can save a lot of trouble and money.
After riding that day, I noticed the overflow tank was ice cold. Upon checking, it turned out the coolant had completely leaked out. This is a pretty common issue – either due to aging pipes developing holes or the fluid level being too low to circulate properly. The overflow tank should warm up after the engine heats up; otherwise, the entire system can't function correctly, and the engine might overheat and stall mid-ride. I recommend regular maintenance, like checking for leaks before topping up fluids and verifying the tank warms up after starting. Ignoring this can turn minor issues into major repairs, costing both money and peace of mind.
The auxiliary tank not getting hot is mostly a cooling issue: insufficient fluid level, leakage, faulty temperature controller, or a broken water pump. First, stop the vehicle and check if the coolant level is adequate, then start the engine and let it run for a few minutes to warm up. If the fan doesn't turn on or the auxiliary tank remains cool, there might be a malfunction. Early intervention is simple: top up the fluid or check for leaks. Delaying could lead to engine overheating damage, affecting riding safety. Don't wait too long—seek professional help.
