coolant reservoir

9. Not enough coolant.

The coolant is the lifeblood of your vehicle’s cooling system. So if you’re low on it, you can expect your engine to overheat anytime soon. You can check on the coolant level through the coolant reservoir tank.

A low coolant condition, however, shouldn’t be taken lightly. The coolant is supposed to stay inside the system for two years at the very least. So if it starts disappearing, you better start checking up your coolant’s route; chances are there’s a leak somewhere.

10. Loose driving belt.

The coolant pump has a pulley that is driven by a drive belt that’s connected to the crankshaft. If the drive belt is loose, it would not effectively transmit the mechanical power from the crankshaft to the coolant pump pulley. It might even slip, which would halt the pump’s operation altogether. Thus, it can cause overheating.

11. Leaky radiator hose.

radiator hose with clamp

Made from rubber and held in place only with clamps, the radiator hose is the most leak-prone of all the cooling system components. It seldom leaks coolant through holes or scratches along its body.

The common problem encountered with the radiator hose is the setting or permanent compression of the hose by the hose clamp. As the coolant heats up, the neck to which the hose is connected expands. And because the hose is made of rubber, it expands along with the neck. But because there’s the clamp tightened around the hose, the hose gets heavily compressed that after the temperature goes down, it is already loose. However, there are some hoses that, instead of becoming loose, get glued to the neck after being heated up.

damaged radiator fins

3. Restricted radiator fins.

If you know your radiator well, you’d know that by radiator fins we mean the tubes or passages in the radiator through which coolant flows. These passages are as wide as possible so that more surface area would be exposed to the cool air, and thus, coolant passing through these fins would cool faster as well.

So just imagine if these fins get restricted—probably by small road debris that got blown to the radiator—air wouldn’t be able to pass through the radiator properly, thus increasing your engine’s tendency to overheat.

4. Coolant combination isn’t right.

Even if the rest of the cooling system’s components are working, the system wouldn’t do its job effectively if the coolant circulating through it isn’t of the right mix. Coolant is a combination of water and anti-freeze or ethylene glycol. It cannot be pure water because water freezes at 0oC and boils at 100oC. It would damage the engine if it freezes in winter and it would be useless as a coolant if it’s already boiling when the engine hasn’t even reached its ideal operating temperature.

The ideal combination is 50% anti-freeze and 50% water. In really cold climate, you can increase the anti-freeze proportion up to a maximum of 70%.

5. Defective radiator fan.

The radiator fan, located behind the radiator, draws cool air from outside to take away heat from the radiator fins. The fan may not be really need if the vehicle is running fast, that’s why in some systems it automatically turns off

if the vehicle is running fast enough. It’s most needed when the vehicle is idling or running so slow there’s insufficient cool air passing through the grille and radiator.

Check your radiator fan’s blades and motor to see if they’re still drawing in enough air for your radiator.