How to fix power washers

Power washers are a must-have for any homeowner. A high-pressure stream of water makes it easy to maintain patios, decks and walkways, and can even be used to clean aluminium or plastic siding on homes. But if the pressure drops or a strange noise develops, doing a relatively easy chore could become difficult or nearly impossible. Taking your power washer to get fixed could dip into your wallet unnecessarily. To diagnose and repair the problem, first make sure to consult your product manual. If all else fails, take your newly found knowledge and price compare parts at your local hardware store. Then, take your power washer to a professional and make sure you aren't being overcharged.

If the pump runs but no flow is produced, this could indicate that the pump needs to be primed. To fix, flood the suction (usually a button you can press) and then restart the pump.

If you have a noisy pump, this could mean that the pump is sucking in air. To fix, check the suction manifold. If air has been trapped inside the pump, you must flood the suction hose and restart. Run the pump until the air has been evacuated. You will need to disconnect the discharge hose from the pump beforehand.

If you hear a loud knocking noise in the pump, chances are that a bearing is worn or broken, or there may be a pulley loose in the crankshaft. To fix, you may need to replace the bearing. Check the crankshaft and tighten any loose screws.

If the pressure gauge is fluctuating and you can't explain why, the valves may be worn or blocked by foreign matter. If the problem hasn't been fixed after cleaning the valves, get them replaced.

Low pressure has many possible causes. Worn nozzles should be replaced (with the proper size). Belts can slip. Make sure all belts are tightened or replaced (with the proper size). During assembly the inlet plumbing may have not been sealed correctly. To fix, disassemble and reseal it.

Make sure the machine has the correct nozzle and that the nozzle isn't worn. A worn or incorrect nozzle can result in low pressure. If correct, the nozzle will match the pressure and flow of the pump. See your product manual for this information.

If the packing is worn, this may result in water leakage from either under the manifold or elsewhere. To fix, install new packing. Likewise, worn seals can result in an oil leak between the crankcase and pumping section. If the crankcase piston rod seals are worn, replace them.

If oil is leaking in the crankshaft area, check the bearing, the crankshaft seal and oil seal o-ring. If the bearing is bad, replace it. If the crankshaft or o-ring are worn, remove the oil seal retainer and replace all damaged parts.

Water in the crankcase may not be caused by a leak, but could be the result of collected condensation from humid air. To fix, change the oil intervals. It's recommended to use a high grade 30 weight (non-detergent) automotive oil.


As various brands differ in structure and function, be sure to consult your product manual before diagnosing and/or repairing your power washer.

Things You'll Need

  • Your product manual and/or maintenance guide
  • Non-detergent 30 weight automotive oil (optional)
  • Various seals and belts
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About the Author

Christopher de la Torre has been writing about science and communication since 1998. His work appears on websites including Singularity Hub and in "Vogue." He holds a Bachelor of Science in biology and a Bachelor of Arts in English from Eastern Connecticut State University and is pursuing a master's degree in English from George Mason University.