Diesel engines in heavy trucks are designed to withstand long hours of operation, extreme conditions, and high loads. Even when they are robust, these engines can develop problems. Whether engine problems are caused by a missed service, a warning sign, or an ignored component, most of them can be prevented.
Here are the most common heavy truck diesel engine problems and how to prevent them.
1. Failing to Start or Hard Starting
If your diesel engine cranks but doesn’t start, shows no response when the key is turned on, or takes a long time to fire up, it has a hard-start problem. Diesel engines can fail to start or suffer hard starts due to various reasons, including the following:
- Dead or weak battery
- Fuel system air leaks
- Problematic glow plugs
- Low compression in the combustion chamber
- Clogged fuel filters
- Injector failure or wear
- Sensor or computer issues
Preventive maintenance can help prevent hard diesel engine starts. This includes:
- Checking battery voltage
- Ensuring connections are clean & corrosion-free
- Testing glow plugs for proper power draw & resistance
- Checking for air leaks, damaged fuel lines, or clogged filters in the fuel system
2. Loss of Power
When your truck’s diesel engine loses power, it can affect drivability and fuel economy. Some of the common underlying causes of performance issues in diesel engines include:
- Clogged fuel or air filters
- A problematic turbocharger
- Engine sensor issues
- Limited fuel delivery
The following steps can often help avoid performance issues with your truck’s diesel engine:
- Replace clogged fuel or air filters
- Check the turbocharger system
- Address low boost pressure, worn seals, or oil leaks
3. Overheating
Overheating can cause internal damage to a diesel engine. This can mean blown head gaskets, cracked or warped cylinder heads, cracked pistons, engine power loss, or a burning odor from fluids. Some of the common underlying causes of truck engine overheating include:
- Low coolant levels
- Problematic water pump or radiator
- Blocked cooling passages
Diesel engine overheating can be prevented using by regularly checking and ensuring coolant levels are maintained, inspecting the water pump and radiator, replacing the thermostat, and flushing the cooling system.
4. Unexplained Excessive Smoke
If your diesel-powered truck is emitting excessive smoke, there may be an issue with the engine. The smoke’s color can typically indicate the kind of underlying problem:
- Black smoke usually indicates excess fuel in the combustion chamber and common factors include malfunctioning injectors or turbochargers, or a clogged filter.
- Blue smoke can mean the engine is burning oil and common causes include problems with turbocharger seals, piston rings, or valve stem seals.
- White smoke is generally a sign of unburnt fuel, faulty injectors, or low compression.
It is recommended to clean or replace air filters on time. You should ensure your truck is also inspected for carbon buildup in the manifold and clogged intercoolers. The turbocharger should also be inspected for worn seals, oil leaks, and boost pressure levels. Contaminated or low-quality fuel can also affect combustion and produce excessive smoke.
5. Skipping Routine Maintenance
Skipping routine maintenance or delaying repairs can become big factors in causing diesel engine problems. While a worn hose or cracked belt may seem like a minor failure, it can create major issues such as loss of oil pressure, overheating, or turbocharger failure.
So, it is recommended to strictly follow a preventive maintenance schedule and ensure thorough visual inspections at every service. All minor issues should be addressed before they turn into major problems.
Diesel engines are prone to many other issues. This includes fuel contamination, electrical or sensor issues, oil leaks, poor lubrication, fuel system failure, Exhaust Gas Recirculation (EGR) system failure, and coolant contamination. Creating and implementing a preventive maintenance schedule can go a long way in preventing most of these issues.
