Diesel Heater Maintenance Schedule

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This schedule outlines routine checks, annual servicing tasks, and long-term maintenance for diesel air heaters used in camper vans, motorhomes, boats and off-grid vehicles. Regular upkeep improves reliability, reduces soot buildup and extends heater lifespan.

Daily / Before Each Trip

Visually check that the exhaust and air intake are not blocked by mud, snow, debris or vegetation.
Listen for unusual noises from the fan or fuel pump.
Ensure the heater has unobstructed airflow at both the intake and warm-air outlet.
Confirm the carbon monoxide (CO) detector is present and functioning.

Monthly

Run the heater on maximum power for 10–20 minutes to reduce carbon buildup (a “burn-off cycle”).
Inspect all visible fuel lines for signs of weeping, cracking or abrasion.
Check electrical connectors for corrosion or loose contacts.
Verify ducting is not crushed, kinked or rubbing against bodywork.

Every 3–6 Months

Clean the heater’s cold-air return vent and warm-air outlet grilles.
Inspect exhaust clamps and mounting hardware for tightness.
Examine the fuel filter (if externally accessible) and replace if dirty.
Check battery voltage and charging system performance, as low voltage contributes to poor ignition and soot buildup.

Annually (Full Service Recommended)

Remove and inspect the glow plug; clean or replace if fouled or worn.
Inspect the combustion chamber for excessive soot; clean if necessary.
Clean or replace the fuel filter.
Check all seals around the heater mounting plate and floor penetration.
Inspect fan motor for dust buildup and assess bearing condition.
Verify exhaust and intake routing for corrosion, damage or leaks.
Test the heater through a full start-run-shutdown cycle.
Replace any hardened or damaged rubber fuel line sections.

Every 2 Years

Replace glow plug as preventative maintenance (recommended for frequent users).
Replace exhaust gasket(s) and inspect muffler for corrosion.
Inspect wiring harness for wear, especially at entry points and sharp bends.
Consider replacing the fuel pump if startup reliability declines.

Long-Term / As Needed

Overhaul burner chamber if performance drops significantly despite routine cleaning.
Replace fan motor if it develops persistent squealing, grinding or wobble.
Replace ducting if it becomes brittle, flattened or heat-damaged.
For heaters used in damp or coastal environments, inspect all metal components annually for corrosion.

Storage (Off-Season)

Run the heater for 10–15 minutes at high power once per month to keep components dry and prevent carbon buildup.
Check that fuel in the tank is clean and appropriate for seasonal temperatures.
Ensure the exhaust remains clear of nesting insects, mud or debris.

Notes

Diesel heaters perform best when run hot regularly; repeated low-power operation leads to soot accumulation.
Using clean, good-quality diesel significantly reduces burner fouling.
Always follow manufacturer-specific maintenance intervals when available.