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Diesel Engine Care & Maintenance: Comprehensive Guide

diesel engine maintenance
Last Updated on Aug 16, 2023 By Lillian Kazmierczak

Diesel engines are more intricate than their gas-powered counterparts. Scheduled maintenance will keep the engine running in prime condition and increase the life of your engine.

Here, we will look at diesel engine maintenance, tips to keep the engine running at its peak, look at specific areas of upkeep that you need to do regularly, and learn the signs of early airlock and how to bleed the system.

Diesel Engine Maintenance Tips

Diesel Engine Maintenance

1. Let the vehicle cool down

Diesel engines run hotter that often leads to overheating. Letting the engine cool down throughout a trip will help avoid this issue.

2. Maintain clean

Dirt and road salt lead to rust and corrosion of engine parts. It is essential to keep these components clean to maintain a long engine life. Always check the owner’s manual before cleaning these components.

Use an engine decreaser to help remove crude and debris. An old toothbrush will help get in places your hands and fingers won’t fit. Use a damp sponge to clean out the engine bay.

Never clean a hot engine. Blow dust and debris from the engine bay using a leaf blower.

If you want to clean the engine deep, cover the non-waterproof parts of your engine with plastic bags and hose down the rest with water.

3. Clean air filters

Dirty and clogged air filters interfere with airflow, increase fuel consumption, increase wear to your engine, create abnormal acceleration, and lessen engine power. Maintaining clean air filters can save you money and diesel repairs.

4. Scheduled oil changes

The best way to destroy a diesel engine is not to change the oil, so get the oil changed regularly; i.e., every 5,000 miles. Check the oil level between oil changes and top off the oil as needed. When changing the oil, change the oil filer too.

5. Keep an eye on your coolant

Antifreeze helps keep the engine cool. In between radiator exchanges, add new antifreeze to maintain a full level in the radiator.

6. Changing fuel filters

Eliminating water in your fuel will help keep your engine from stalling, ensure you don’t experience a decrease in horsepower, and stop your fuel injectors from imploding.

Change the primary and secondary filters at the same time. Most manufacturers recommend changing the fuel filters between 10,000 to 15,000 miles.

7. Maintaining your air filter

You can find the air filter in the cold air collector box near the front of the engine. In between air filter replacements, check the filters which can become clogged easily. Check air filters every 12,000 miles and replace them as needed.

8. Maintaining fluid levels

Your diesel engine runs best when all the fluids are at maximum level. Check the fluids regularly to avoid slow engine starts and increase the engine’s life.

9. Checking the radiator

It is essential that you check the radiator to eliminate engine component distortion and prevent engine failure.

Doing regular radiator exchanges will remove pollutants and debris from your antifreeze. Most manufacturers recommend doing the radiator exchanges every 40,000 to 60,000 miles.

10. Tune-ups increase diesel engine longevity

Have the engine tuned up regularly if you want to get the maximum fuel usage, best speed, and optimum power from your engine.

11. Maintaining your exhaust system

Particles that turn to carbon and ash will gum up your diesel particulate filter. Keep an eye on the filter and if you notice an increase in regeneration, have the exhaust system examined.

12. Sustaining moderate RPMs

Driving your diesel engine at high RPMs can ruin the transmission. Keep your speed on the moderate side consistently.

13. Draining the water separators

Water separators wick the water from the fuel. Drain the separators weekly by turning the petcock and letting the water drain into a container.

Diesel Engine Service Checklist

Diesel Engine Service Checklist

  • Diesel electrical

The alternator charging rate, battery horn, and lights will need testing to make sure they are in running order.

  • Your engine

Check the alternator belt for quality and tension. Next, check the coolant to see if the antifreeze is at its peak and the level is high enough. Finally, make sure the cooling fan is in good condition and working properly.

  • The brake system

Top off the brake fluid, and check for leaky calipers. Check brake drums, discs, and pads for damage.

  • The drive system

Examine the clutch, driveshaft gaiters, and gearbox for potential problems.

  • Suspension and steering

Test the power steering and suspension to see if they are functioning correctly. Be sure to check for wear and tear.

  • Doing the road test

Check for tire and steering issues by driving the vehicle and seeing how it handles during the drive.

How to Winterize Diesel Engines?

Step 1: Fuel preparation

The paraffin wax in diesel fuel hardens as the temperature drops. Adding a cold-flow improver with wax anti-settling agents and de-icers can solve this problem. However, be careful of over-adding; it will decrease fuel consumption.

Step 2: Swapping out filters/checking water separators

Changing the water filters and emptying the water separators will prevent fuel gelling.

Step 3: Getting the battery ready

Check the battery for an adequate charge, clean and inspect connectors and cables.

Step 4: Cooling system inspection

Check the strength of your antifreeze and ensure it is at the maximum level. Also, make sure the radiator and its components have no damage or leaks.

Step 5: Checking hoses and belts

Tighten loose hose clamps and inspect hoses and belts for cracks and hardening.

Avoid these bad diesel engines habits

1. New diesel engines

  • Air leak reminders

When a bubble of air interrupts the fuel flow in the system, it creates an airlock. You will need to do a system bleed to correct the issue.

  • Fuel gelling check

Add a fuel additive to prevent gelling so you can start the diesel engine in the cold weather.

  • Oil additives reminders

The engine’s heat can break down the smaller engine components, and using oil additives will increase engine lubrication.

2. Old and used diesel engines

  • Don’t let engines get hot

Turbochargers need a break after driving a distance. Put the car in neutral and let the turbochargers cool down for 20 seconds to 2 minutes.

  • Don’t forget to empty the water separator

Full water separators can’t remove the water from your fuel. Make sure to empty them weekly.

  • Cheap replacement parts

The stronger the engine, the better the parts it will need. Higher-quality parts ensure your diesel engine will continue to run well.

3. Both used and new diesel engines

  • Don’t neglect the coolant

Coolant issues lead to engines overheating. Check the radiator/coolant if:

  • Steam is coming from under the hood
  • Leaked green/orangish coolant is on the ground under your vehicle
  • An odor from the engine that reminds you of maple syrup
  • Avoid too many short trips

The engine can’t warm up enough during short trips to burn off the soot.

  • A word about mixing coolants

Never mix coolants! The combination can create a chemical reaction that can destroy the engine or its components.

Different faulty injector signs

  • Check engine light is on
  • Fuel leaks
  • Lack of fuel to the engine causes insufficient idling
  • Vibration in the engine from improper cylinder firing
  • Misfiring of the motor causes acceleration issues
  • Increase in fuel use to produce better combustion

Benefits of diesel injector cleaners

  • Offsets issues caused by low sulfur fuels
  • Prevents component corrosion
  • Increases lubrication of engine and fuel system
  • Decreases emissions levels
  • Removes stuttering in engine
  • Improved fuel cetane numbers
  • Gets rid of engine misfiring
  • Cold starting improvement
  • Restores throttle response

Regeneration types: Diesel particulate filters

1. Active DPF regeneration

The active diesel particulate filter burns off extra filter soot by injecting fuel into the filter. This process increases the life of the DPF and decreases fuel usage. It also reduces the purchase of expensive filters as a bonus.

2. Passive DPF regeneration

The easiest way to clean the diesel particulate filter is by driving the car for 30 to 60 minutes. This will raise the exhaust temperature enough to burn off the filtered soot.

Different types of diesel engine oils

Before buying any oil, check the owner’s manual for recommendations.

Synthetic oil – Helps the engine burn fuel at lower temperatures, allowing the engine to run efficiently.

High viscosity oil – Affects engine-level performance and fuel consumption determined by heat created in the bearings, cylinders, and gearsets.

Different types of diesel fuels

  1. Hydrogenated fats and oils – The alkanes created by the triglyceride conversion help to hydrate and refine this fuel.
  2. Synthetic diesel – Offers a decreased carbon fuel option that reduces the level of sulfur and emissions in the fuel.
  3. Dimethyl ether or DME – Created to reduce high cetane levels in fuel so Australian vehicles could meet carbon-reducing goals.
  4. Biodiesel – Increases engine blockages, corrosion of fuel injectors and their components, and creates trigger pump seizures. The cause is the recycled restaurant grease, animal fats, and vegetable oils used to produce this fuel.
  5. Petroleum diesel – Mostly used by construction vehicles, farm equipment, and trains. Fossil diesel is its other name.

How to Bleed the Diesel Fuel System?

The early warning sign of airlock

  • Car stalling
  • Engine hiccups
  • The vehicle won’t start

Bleeding your fuel system

Once you have identified the airlock, you need to bleed the system.

You will generally find the bleed screws on the first filter. Turn the screw half a turn, loosen it more if needed—no more than four turns.

Have a container ready as you pump the plunger on the lift pump (the lift pump is attached to the primary fuel filter and mounted on your engine). Watch the bleeder screw as the air bubbles leave the system, followed by fuel.

Once you get bubbleless fuel, retighten the screw and continue pumping the plunger. You stop air from getting back into the system and keep the pressure in this manner. If your engine has a secondary fuel filter, repeat these steps.

You will need to bleed each injector and the injector pump if the airlock remains.

About the author

Lillian Kazmierczak

As far as I can remember, I would say I have been a car nut for my whole life. My father was a car dealer who used to change and repair his cars himself. This gave me the opportunity to get around all sorts of cars and get my hands dirty repairing vehicles from an early age.

A great fan of Japanese quality and German preciosity, my deep passion lies in older models that I believe have a flair that takes me back to my childhood! I also love their extraordinary durability and reliability when compared to today’s modern models.

When not out taking a ride, I enjoy socializing with fellow motorheads online and consuming any car facts and figures I can get my mind on!

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