How to Maintain a Honda WT30 Trash Pump

Honda_WT30Honda’s WT30 trash pump can safely move massive amounts of wet debris and water, but only if it is maintained properly. Following this guide will ensure this pump will provide years of trouble-free service.

Repairing Your Pump Safely

Never run the engine in an enclosed space. Carbon monoxide from the exhaust can cause poisoning and death.

Let the engine cool down before working on the pump. The exhaust can retain heat long after the pump has been shut off.

Don’t run the engine until the repair has been completed or specifically instructed to do so during the repair.

To reduce the chance of gasoline ignition, only use non-flammable solvents when cleaning parts. Keep all sources of spark and flame away from the pump.

Maintenance Schedule

Before each use, check the engine oil level and the air filter. After each use, flush the pump casing.

The oil should be changed after the first 20 hours or month of use.

The air filter should be cleaned every 50 hours or three months.

After every 100 hours of use or 6 months, the oil should be changed, the sediment cup should be cleaned, the spark plug checked, and the spark arrester cleaned.

Every 300 hours of operation or every year, the air filter and spark plug should be replaced. Honda also recommends having the idle speed, valve clearance, fuel system and pump be inspected by a professional mechanic.

The WT30’s combustion chamber should be professionally cleaned after every 500 hours.


The engine in the WT30 is designed to run off of 86 octane or greater automotive unleaded gasoline. It should be filled only when the engine is off, and the fuel level should be no higher than the top of the internal screen.

Engine Oil

The Oil Alert system will automatically stop the engine if the oil level is too low to prevent internal damage, but the oil level should still be checked regularly. To do so, unscrew the oil filler cap and wipe off any oil. Reinsert the cap without screwing it back in, then pull it out and check the markings on the cap stick: if it’s low, add more oil.

To change the oil, place a container under the motor and remove the drain plug at the base of the engine. Once the oil has drained completely, replace the plug and add oil through the filler neck.

The engine holds 0.63 quarts (0.6 liters) of oil. Honda recommends 5W30 for use at temperatures below 32°F (0°C,) 10W-30 for temperatures above -4°F (-20°C,) or SAE 30 for temperatures above 50°F (10°C) and higher. Oil should meet API service category SJ or later.

Air Filter

To inspect the filter, remove the wing nut and air cleaner cover, then separate the foam and paper elements. The filters should be replaced if they show any signs of damage.

To clean the paper filter, tap it gently to loosen any dirt, or use compressed air to blow out any dust. The foam element should be washed in soapy water and rinsed thoroughly. Once it has dried, soak the foam in engine oil and squeeze out any excess. Wipe dirt away from the cover and base and make sure the gasket on the filter base is still in place before reinstalling.

Sediment Cup

Move the fuel valve lever to the “Off” position. Remove the sediment cup and O-ring from the carburetor. Wash both in a non-flammable solvent and let them dry thoroughly. Reinstall the cup and ring, then move the fuel valve lever to “On,” checking for leaks.

Spark Plug

To remove the spark plug, take off the spark plug cap, then unscrew the plug with a 13/16″ spark plug wrench. When reinstalling a new plug, turn it another 1/2 turn after the plug seats to compress the sealing washer. When reinstalling an old plug, turn it another 1/8-1/4″ after the plug seats.

The spark plug will need to be replaced if it is fouled, the electrodes are worn or if the insulator is damaged. The spark plug gap should be between 0.028 and 0.031 inches (0.70-0.80 mm.)

Spark Arrester Service

The WT30 doesn’t come with a spark arrester, but one can be installed in the muffler if needed to comply with local fire safety laws.

To access the spark arrester, remove the three 5 mm screws from the top of the muffler protector and three more screws from the sides of the protector. Lift both halves of the protector off the muffler. Remove the two 4 mm screws holding the spark arrester inside the muffler, then gently slide it out.

To clean, brush the surface off to remove any carbon deposits. Replace the spark arrester if it has any breaks or holes.

Pump Casing

Remove the drain plugs from the casing and pump cover. Once the water has drained out, loosen the pump cover knobs and open the cover holders. The cover and volute case should slide off. Clean any debris that are in these parts.

There are two O-rings on this assembly: one on the end of the volute case and a second on the edge of the pump cover. Make sure these are fitted firmly before reassembling. Follow the removal steps in reverse, hand tightening the cover knobs. Check the cover for leaks.

Getting Parts for the WT30

Honda Lawn Parts is a full line dealer of OEM Honda small engine parts. Whether you need to add a spark arrester or get a replacement spark plug, they have what you need. Visit them online at

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