Why Is My Diesel Engine Overheating?

Keeping the temperature in check is vital for your diesel engine’s long and healthy life. The internals of a diesel engine are different to those found in the more common gasoline ones. Therefore, if your diesel vehicle is overheating, the cause might not be immediately obvious.

If it keeps overheating, it’s best to schedule an appointment with your reliable diesel engine specialist for a correct diagnosis of the problem.

Abnormally high engine temperatures and constant overheating can compromise the fuel injection system, among other problems. If your fuel injection system has been damaged by overheating, here are some quality replacements you might want to look at. Here’s a look at the most common culprits behind an overheating diesel engine.

Clogged or Leaking Fuel Injectors

When the injectors are clogged or leaking fuel, the engine is not receiving the sufficient amount of fuel. The engine starts to work harder to compensate for the lack of fuel which may cause it to overheat. Get your injection system serviced regularly to make sure it remains in fine working order. Emerald Diesel specialises in the service and repair of diesel pumps.

Thermostat Failure

There is an electrical thermostat located in the engine to sense and regulate engine temperatures. Whenever engine temperatures rise, the thermostat detects it and activates the cooling system. If the thermostat is faulty or there is a broken sensor, the cooling system will not be activated.

Broken Cooling Fan

This is an obvious one. If your cooling fan is not working, your engine is not receiving the sufficient amount of air needed to remain cool. Sometimes, the problem is an electrical one and some wire tweaking can resolve it. However, in some cases, you may need to repair or replace the entire fan.

Leaking/Bubbling Coolant

Your vehicle is overheating, and your coolant level keeps decreasing. You notice bubbling in the coolant mixture. All this could very well indicate a blown or damaged gasket. The best thing to do is get your vehicle inspected by a professional. Failure or delay can result in extensive engine damage.

Loose Radiator Filler Cap

In some instances, the cause of your engine overheating may be something as simple as a loose radiator filler cap. If the radiator cap isn’t tightly sealed, the internal radiator pressure can drop. The reduced pressure in the radiator can cause the boiling point of the cooling mixture to become less than normal. This will lead to the whole system boiling up very quickly. Remember, a simple thing such as a radiator cap can ruin the entire engine.


While there are other causes for your engine to overheat, these are the most common. If you are suffering similar problems with your diesel engine, schedule an appointment with Emerald Diesel now for all your diesel specialist needs!