If you own equipment, machinery, or a truck that runs on diesel, keeping the engine clean is essential. A neglected engine collects dirt, grease, and grime, which can lead to overheating, reduced efficiency, and even long-term damage.
There’s an old myth that diesel engines shouldn’t be cleaned. That’s not true. Regular cleaning extends the lifespan of your equipment and prevents costly repairs.
Below, we’ll walk you through the right way to clean your diesel engine, the best degreasers to use, and what to avoid.
Why Cleaning Your Diesel Engine is Important
Diesel engines are built to handle tough conditions, but that doesn’t mean they should be ignored. Over time, dirt, oil, and road grime can:
- Trap heat and cause overheating
- Clog air filters and reduce performance
- Cause corrosion of metal parts
- Make it harder to spot leaks or maintenance issues
By keeping your engine clean, you improve its efficiency, prevent damage, and make inspections easier.
Step-by-Step Guide to Cleaning Your Diesel Engine
Cleaning your diesel engine isn’t complicated, but it does require the right approach. Follow these steps to do it safely and effectively.
1. Remove Loose Dirt and Debris
- Use a stiff-bristle brush to manually remove dirt, leaves, and debris trapped under the hood and around the grill.
- Check air intake areas and radiator fins—these spots collect a lot of dust.
2. Warm Up the Engine
- Run the engine for 5 to 10 minutes before cleaning.
- This helps loosen grease and grime, making it easier to remove.
3. Cover Sensitive Parts
- Use plastic bags and rubber bands to protect key components:
- Alternator
- Air intake
- Power steering reservoir
- Exposed sensors
- This prevents water and cleaning solutions from damaging electrical parts.
4. Apply an Engine Degreaser
- Always spray from bottom to top to prevent cleaner from dripping on you.
- Let the degreaser sit for 5 to 10 minutes, depending on how dirty the engine is.
5. Scrub Tough Areas
- Use a long-handled brush to reach deep crevices and remove stubborn grime.
- If necessary, reapply degreaser for extra cleaning power.
6. Rinse Gently
- Do not use high-pressure water. A garden hose with a gentle stream is enough.
- Start from the top and work your way down to avoid pushing debris into engine components.
7. Let the Engine Dry
- The engine’s heat will naturally evaporate water within an hour.
- If you’re concerned about water spots, wipe down metal surfaces manually.
Choosing the Right Degreaser for Diesel Engines
Not all degreasers are safe for diesel engines. Some contain chemicals that can damage metal, plastic, or electrical connections.
Best Degreasers to Use
- Citrus-based or water-soluble degreasers – Effective and safer for most engine components.
- Diluted dish detergent – If you don’t have a dedicated degreaser, dish soap works in a pinch.
Degreasers to Avoid
- Organic, all-natural products (like Simple Green) – Can damage high-strength steel, aluminum, and titanium over time.
- High-alkaline cleaners (like Formula 409 or Fantastic) – These can cause hydrogen embrittlement, making metal brittle.
Common Mistakes to Avoid When Cleaning Your Diesel Engine
1. Using Too Much Water
Pressure washers and excessive water can push moisture into electrical components, leading to short circuits and corrosion. Always use a gentle stream of water.
2. Skipping Protective Covers
Leaving sensors, alternators, or air intakes exposed can lead to expensive damage. Take the extra time to cover them properly.
3. Using Harsh Chemicals
Some degreasers break down grease but also eat away at metal and rubber parts. Stick to engine-safe cleaners.
4. Cleaning Too Often
Diesel engines don’t need frequent washing. Clean them every few months or whenever you notice excessive buildup.
Final Thoughts
Keeping your diesel engine clean improves performance, prevents overheating, and extends its lifespan. By using the right cleaning method and avoiding common mistakes, you can maintain your equipment without causing damage.
Regular maintenance goes beyond just cleaning. Inspect your engine for leaks, check fluid levels, and ensure air filters are clear. A well-maintained diesel engine keeps you on the road (or job site) longer.