A truck engine overheating is not just a safety concern. If you own a commercial business, overheating engines in your fleet can cause serious logistical issues and costly repairs, eating into your profit margins.
Here, we’ll look at some of the most common overheating truck causes, how to identify them, and how to prevent them.
Radiator coolant loss
One of the most common causes for a truck overheating is a loss of coolant, which absorbs heat from your engine. You may be able to check the coolant levels yourself and top up if necessary.
If the coolant is running unexpectedly low, there may be a leak. In this case, it’s best to visit a mechanic that can help find and fix the issue.
Blown head gasket
If the temperature gauge goes up very suddenly and you see steam rising from beneath the bonnet, you could have blown a gasket.
Pull over safely as soon as possible and turn off the engine - but don't open the bonnet immediately! Let the vehicle cool down for a good while until you can safely touch the engine components without risk of burns.
Once the engine is cool enough to touch, you can open the bonnet and visually inspect the area around the head gasket for signs of a leak. The head gasket is typically located between the engine block and the cylinder head, which is usually the large metal casing on top of the engine. Look for trails of coolant around the head gasket, which would indicate a breach in the seal.
A blown head gasket is a serious issue that requires professional repair and it's not advisable to fix it yourself. Call roadside assistance to have your vehicle towed to a qualified mechanic for proper repair.
Faulty radiator cap
A damaged radiator cap can cause issues with the cooling system inside your truck, leading to overheating. If the cap is stuck, coolant overflowing from radiator to tank is hindered, causing pressure to build inside the system, which can lead to a leak.
Likewise, if it doesn’t seal properly, too much air will get into the system, creating air pockets that make it impossible for the engine to maintain a consistent temperature. A specialist mechanic should be able to check your truck for radiator cap issues.
Airlocks
Airlocks refer to air bubbles that become trapped in the liquid coolant, preventing the proper flow of fluid through the system.
While you can't directly see an airlock, there are signs to watch for:
- Engine Overheats: This is the most common sign. The temperature gauge climbs despite having enough coolant, because the air bubbles block the flow.
- Heater Not Working: Even with a hot engine, if your heater blows cool air, air might be stopping hot coolant from reaching the heater core.
- Coolant Level Fluctuations: Airlocks can sometimes cause the coolant level gauge to swing erratically, even if there's no actual leak.
If you suspect this is the cause of your truck overheating, you can run the engine at idle for a while to try and remove the air bubble from the cooling system. If this doesn’t work, you should have your truck towed to a qualified mechanic to investigate the issue further.
Blocked thermostat
The engine thermostat is what regulates the steady flow of coolant. If this gets stuck in an open or closed position, your engine may encounter problems due to excessive or insufficient coolant. If the engine of your truck suddenly dies or starts rapidly overheating, a blocked thermostat could be the cause. If this is the case, you’ll need to tow your truck to a repair shop for a replacement.
How to prevent truck overheating in the future
If you or one of your truck drivers has had to contend with an overheating engine, you’ll already know how costly repairs can be. Staying on top of a solid maintenance schedule can prevent trucks from overheating, improve performance, and even extend their lifespan.
One of the most important effective maintenance tasks is making sure your trucks are always topped up with the best quality fluids for their vehicle type, from high-performance engine oil and transmission fluid to coolant.
Browse the Gulf Oil range of specially formulated lubricants for commercial vehicles here.