My vehicle has started overheating

Engine Heat: Why Has My Vehicle Started Overheating?

Engine heat is primarily generated from the fuel burn, plus a little from mechanical friction. As a rough guide, that heat divides three ways:

• about one-third goes straight out the exhaust;
• about one-third is used to power the engine;
• about one-third is removed by the coolant, plus a small amount by direct radiation.

For example, heat is conducted from the pistons to the rings, then to the cylinder wall, and then to the coolant. It’s also conducted from the piston to the oil squirted under it, and then to the coolant. Finally, heat is lost from the coolant to the air via the radiator.

Sometimes the Reason Is Obvious

Sometimes the cause of overheating is easy to spot:

• a blown hose;
• a leaking water pump or failed thermostat;
• a blocked radiator or old glycol;
• built-up oil sludge in the engine;
• poor engine maintenance.

Bear in mind that once an engine overheats, it also stresses and weakens other components, which may then be ready to fail as well. Quite often, though, the cause is not so obvious.

Stopping Your Vehicle From Overheating

There are many reasons why vehicles start overheating, but through a simple process of elimination you can often fix the problem quickly and easily.

1. Flush Out the Radiator and Cooling System

The cooling system can accumulate rust and mineral scale deposits. Even a tiny coating of mineral scale has a significant effect on reducing cooling efficiency. Another problem occurs when different types of coolant have been mixed — they form a sludge that prevents proper cooling. Cleaning with RMI-25 Cooling System Treatment is the easiest way to remove mineral scale, rust and sludge. Simply add it to the coolant system and drive normally for a week or two; all the deposits end up in the overflow bottle, where they can be removed. (See our full guide on how to flush a radiator with RMI-25.)

2. Remove Built-Up Engine Oil Sludge

Pistons are the hottest parts of the engine, and any carbon in the ring grooves won’t allow heat to conduct to the rings, cylinder wall and then the coolant. The fix is simply to change the oil using Flushing Oil Concentrate — this immediately cleans up the piston rings and allows good heat transfer. Oil that gets too dirty with black soot absorbs heat rather than readily conducting it away through the oil cooler to the coolant system; Flushing Oil Concentrate fixes this too, as well as removing troublesome engine oil sludge.

3. Remove Built-Up Carbon From Cylinders and Exhaust Areas

Heavy carbon deposits around exhaust valves and ports allow more heat to build up in the engine. This doesn’t need a mechanic, though — simply add FTC Decarbonizer to your fuel and drive normally. The carbon burns away as you drive, and the engine can “breathe” efficiently again.

If your diesel runs hot specifically under load, it’s worth understanding the real cause of diesel overheating problems — often dirty oil rather than the cooling system itself.

For any questions about our Overheating Pack, contact the team at Cost Effective Maintenance on 07 3376 6188.