Complete Guide to Diesel Heater Maintenance (With Tips for Peak Performance)

How to Keep Your Diesel Heater Running Smoothly

Diesel air heaters are one of the most reliable ways to stay warm when camping in a van, caravan, shed, or off-grid setup. But like any fuel-burning appliance, they require a bit of maintenance to work properly over time.

This guide covers everything you need to know to keep your diesel heater clean, efficient, and ready for winter.

Why Maintenance Matters

Over time, carbon builds up inside the combustion chamber, glow plug screen, and exhaust system. The fuel line can trap air, or the pump might lose its prime. If the power supply is unstable, the heater may throw error codes or fail to start. Simple routine checks can prevent all of this.

Regular maintenance helps you:

  • Extend the life of your heater
  • Improve heating efficiency
  • Prevent startup failures and smoke
  • Avoid expensive part replacements

 

Maintenance Checklist

1. Power Supply

  • Always use a fully charged 12V battery
  • Avoid running the heater while a battery charger is connected. This can cause voltage drops or surges, especially during startup.
  • Use at least 4mm² wiring and check that terminals are clean.

Photo: Clean battery terminal and proper wiring

2. Glow Plug and Screen

  • Remove the glow plug and inspect it for black carbon or corrosion
  • Check the mesh screen behind the glow plug. If it is clogged, bent, or damaged, it should be replaced
  • Clean the area with a soft wire brush and compressed air if needed

Photo: Used glow plug screen with carbon built up.

3. Combustion Chamber

Dust and moisture can build up inside the housing if installed in a dirty or damp location.  Make sure to keep it clean:

  • Wipe down external vents and inspect the inside of the casing during routine checks
  • Store portable models in a dry location when not in use
  • Open the heater and check inside the chamber for carbon build-up
  • If it's blackened or oily, clean it carefully with a brush or vacuum

Photo: Clean Heater Chamber

4. Fuel Line and Pump

  • Fuel line should be short and as straight as possible, without loops or excess
  • Make sure there are no air bubbles or loose connections
  • Replace old filters and listen for the pump ticking when the heater starts

Photo: Improperly routed fuel line

5. Air Intake and Exhaust

  • Remove the intake and exhaust pipes and check for blockages or soot
  • Clear out bugs, dirt, or any buildup that might restrict airflow

6. Fan and Air Circulation

  • Check that the fan blades spin freely and are not clogged with dust
  • If you hear squealing or rubbing, clean the blades and inspect for wear

7. Run the Heater on High Now and Then

Using the heater only on low can cause carbon to build up faster. Run it on high for at least 15 to 30 minutes once a month, especially during winter.

8. Check Your Fuel Quality

  • If your heater has been sitting unused for a while, drain the tank and refill it with fresh diesel
  • Old or contaminated fuel can lead to startup failure, excessive smoke, or dirty combustion
  • Avoid mixing additives unless recommended for diesel heaters
  • Use a fuel tank cover to protect against dust, UV exposure, and accidental knocks. This helps maintain fuel quality and prevents cracking or warping of the tank over time
  • Make sure the fuel cap seals properly to avoid water or debris contamination
Photo: Fuel Tank Cover

10. Inspect Wiring and Connectors

  • Periodically check all wiring connections, including the fuse and control screen
  • Look for any signs of corrosion, pinched wires, or loose terminals
  • Keep electrical connectors clean and dry—use dielectric grease if necessary

Signs That Maintenance Is Needed

  • Error codes like E-03, E-08, or E-10
  • Heater starts but blows only cold air, then shuts down
  • Excessive smoke or strange smells
  • No clicking from the fuel pump
  • Unusual noises from the fan

Tools That Help

  • 12V multimeter
  • Wire brush and compressed air
  • Basic hand tools (screwdriver, Allen key)
  • Replacement glow plug or screen
  • Silicone sealant for resealing the base

What If It Still Doesn't Work?

If the heater still won’t start after a full clean and check, here’s what to look at next:

  • The glow plug may be weakened even if it glows when tested
  • Carbon inside the combustion chamber may still be blocking ignition
  • The fan may be weak or not spinning at full speed
  • The control board may be shutting down the heater prematurely

If you’ve checked all the above and are still unsure, send us a message with photos of your setup and we’ll help from there.

Need Parts?

We stock all common diesel heater parts including glow plugs, mesh screens, fans, fuel lines, filters, and upgraded silencers. Check them out here:

ontrackoutdoor.com.au - Diesel Heater Parts

Got questions or need help choosing parts? Get in touch with our team, we're here to help. You can contact us via info@ontrackoutdoor.com.au or Messenger.