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Diesel Engine Maintenance: What to Look For When Inspecting a Diesel Engine

August 5, 2024

A service tech inspecting the diesel engine of a large machine

Diesel engines provide the muscle needed for heavy equipment to lift, dig and move massive loads with remarkable efficiency. These engines are designed for high performance under challenging conditions, but that doesn't make them invincible. Regular inspections and preventive maintenance are essential to keep these engines running smoothly and to extend their lifespan.

Frequent inspection allows you to catch minor issues before they become major problems. By regularly examining key components such as the fuel system, cooling system and exhaust, you can identify wear and tear early on. 

This approach not only helps prevent costly repairs but also minimizes the risk of unexpected downtime, which can result in additional costs. By committing to a preventive maintenance routine that incorporates thorough inspections, you can keep your heavy equipment in top shape, securing a solid return on your investment.

Checklist for Diesel Engine Inspections

Here are some key areas to pay attention to while inspecting your machine’s diesel engine.

Visual Inspections

1. Engine Exterior: Examine the overall condition; look for signs of dirt, leaks or corrosion. Pay attention to any loose or missing bolts.

2. Belts and Hoses: Check for cracks, wear or fraying in belts. Hoses should be inspected for leaks, bulges or soft spots.

3. Cooling System: Inspect the radiator and coolant lines for any signs of leakage or corrosion. Make sure that the coolant reservoir is at the appropriate level and the color is consistent with the manufacturer’s guidelines.

Fluid Inspections

1. Oil Level and Condition: Use the dipstick to check the oil level. It should be within the recommended range. Inspect the oil's color and texture; it should not be excessively dark or gritty, which could indicate contamination.

2. Coolant Level and Condition: Ensure the coolant is at the right level and appears clean. A milky appearance could suggest contamination.

3. Fuel System: Check for leaks in fuel lines and connections. Examine the fuel filters; they should be clean and free of debris.

Battery and Electrical

1. Battery Condition: Inspect for corrosion on terminals and ensure the battery is securely mounted. Test the voltage to ensure it's holding a full charge.

2. Wiring and Cable Conditions: Look for any frayed or damaged wires. Secure any loose connections to prevent electrical issues.

Air Intake System

1. Air Filters: Check the air filter for dirt and debris; replace it if necessary. Clogged filters can reduce engine efficiency and cause damage.

2. Intake Manifold: Inspect for leaks and ensure it is securely fastened. Any cracks or gaps can lead to poor engine performance.

Exhaust System

1. Exhaust Manifold: Look for cracks or leaks which could cause reduced engine performance and dangerous emissions.

2. Muffler and Emissions System: Ensure the muffler is secure and check for any signs of rust or holes. Inspect the emissions system for compliance with environmental regulations.

Operational Inspection

1. Startup: Observe how the engine starts; it should turn over quickly and smoothly. Prolonged cranking or hard starts can indicate underlying issues.

2. Smoke/Emissions: Evaluate the color of the smoke from the exhaust. Blue smoke can indicate oil burning, while black smoke suggests incomplete combustion.

Commonly Replaced Components

Certain components in diesel engines are subjected to constant wear and tear, so you may need to replace them more often. Here are some of the most commonly replaced components and the signs that indicate they need attention.

Oil Filters

Over time, oil filters may become clogged, reducing their efficiency. Signs that an oil filter needs replacement include sluggish engine performance and dirty oil during inspections.

Fuel Filters

When fuel filters become clogged, they can restrict fuel flow, causing poor engine performance and difficulty starting. Replace fuel filters regularly to maintain optimal fuel quality.

Air Filters

Air filters block dust and debris from entering the engine. A clogged air filter can lead to diminished engine performance and increased fuel consumption. Replace air filters if you notice a loss in power or poor fuel efficiency.

Belts

Belts tend to wear out over time due to heat and tension. Signs of wear include cracking, fraying or slack. Replace worn belts to prevent engine misfires and overheating.

Hoses

Over time, hoses in the hydraulic system can become brittle or develop leaks. Inspect your machine’s hoses regularly and replace them if you find signs of swelling, cracks or leaks.

Fuel Injectors

Fuel injectors deliver fuel into the combustion chamber. When clogged or faulty, they can cause rough idling, poor acceleration and reduced fuel efficiency. Replace your machine’s fuel injectors if you experience these symptoms.

Glow Plugs

If the engine is hard to start or emits white smoke on startup, it may indicate failing glow plugs, which should be replaced right away.

Gaskets

Over time, gaskets in your machine’s engine can degrade, causing oil or coolant leaks. Gaskets should be replaced once they start exhibiting signs of wear.

Common Issues Associated with Construction Equipment Engines

Due to the nature of construction, heavy equipment used for construction projects may encounter specific performance issues. Here are some of the common engine problems associated with construction equipment.

Overheating

Overheating can result from a malfunctioning cooling system, low coolant levels, or blocked radiators. It can cause severe damage to engine components like gaskets, cylinder heads and pistons.

Oil Contamination

Contaminants in the oil, such as dirt or debris, can cause engine wear and increase friction. This can lead to premature failure of critical engine parts like bearings and crankshafts.

Fuel System Problems

Issues such as clogged fuel filters or contaminated fuel can lead to poor engine performance and reduced fuel efficiency.

Electrical Failures

Electrical problems can stem from corroded connections, dead batteries or damaged wiring. These issues can lead to malfunctioning sensors and various performance issues..

Transmission Problems

Transmission issues can result from low fluid levels, worn-out clutches or damaged gears. These problems can cause slipping or, in some cases, complete transmission failure.

Additional Tips and Information

Preventing common engine problems in construction equipment requires a thorough preventive maintenance routine. Here are some additional tips to keep your diesel engine in top condition.

Establish a Regular Maintenance and Inspection Schedule: Consistency is key. Develop a detailed maintenance schedule, including daily, weekly and monthly inspections. Adhere strictly to this schedule to catch potential issues early and ensure your machine’s components are in proper working order.

Properly Lubricate Moving Components: Proper lubrication reduces friction and wear on critical engine parts. Use high-quality lubricants, as indicated in your machine’s service manual.

Keep Up with Cooling System Maintenance: Overheating can cause severe engine damage, so ensure the cooling system is functioning properly. Regularly flush and replace coolant, inspect hoses for leaks or cracks, and keep the radiator clean to maintain efficient cooling.

Utilize Diagnostic Tools: Modern diagnostic tools can identify issues before they become severe. Invest in diagnostic equipment compatible with your equipment and perform regular diagnostics to detect engine problems early.

Educate and Train Operators: Ensure that all equipment operators are well-trained in basic engine maintenance and the signs of common problems. A knowledgeable operator is the first line of defense against engine troubles.

Maintain a Clean Engine Environment: Dust and debris can cause contamination and overheating. Regularly clean the engine bay to prevent build-up, and store equipment in a sheltered environment when not in use.

Use Quality Parts and Fluids: Always use manufacturer-recommended parts and high-quality fluids for replacements and top-offs.

Final Thoughts

Regular diesel engine inspections and maintenance aren’t just best practices, they are essential for the longevity and efficiency of your heavy equipment. 

By consistently inspecting key components and addressing wear and tear before it turns into serious damage, you can prevent costly repairs, avoid unexpected downtime and extend the life of your equipment.

The EquipmentShare Shop offers a comprehensive range of OEM and aftermarket parts for heavy equipment diesel engines, helping you maintain the longevity and performance of your heavy machinery. Don’t see exactly what you’re looking for? Reach out to our dedicated parts experts and get personalized assistance.

About EquipmentShare

Founded in 2015 and headquartered in Columbia, Mo., EquipmentShare is a nationwide construction technology and equipment solutions provider dedicated to transforming the construction industry through innovative tools, platforms and data-driven insights. By empowering contractors, builders and equipment owners with its proprietary technology, T3, EquipmentShare aims to drive productivity, efficiency and collaboration across the construction sector. With a comprehensive suite of solutions that includes a fleet management platform, telematics devices and a best-in-class equipment rental marketplace, EquipmentShare continues to lead the industry in building the future of construction.