Pressure washers & generators

Gas pressure washer is leaking oil

Oil leaks on gas pressure washers usually come from a worn crankcase seal, an overfilled sump, or a loose drain plug, and are worth fixing promptly since low oil can trigger a safety shutoff or damage the engine.

Difficulty
Easy
Time
15–30 minutes
DIY cost
$5–$20
Pro cost
$80–$180

Symptoms

  • Oil spots under the engine after storage
  • Visible oil residue near the drain plug or seams
  • Oil level drops faster than normal
  • Smoke or burning smell from the engine area

Likely causes

  • CommonOverfilled crankcaseToo much oil can seep past seals or vent out the breather; check level against the dipstick's full mark.
  • CommonLoose or damaged drain plugA plug that isn't seated with its washer, or has a worn gasket, will weep oil.
  • PossibleWorn crankshaft sealSeals harden with age and heat cycles, letting oil seep out around the shaft.
  • PossibleMachine stored on its side or tiltedStoring or transporting the unit at an angle can let oil migrate out through the breather or spark plug hole.
  • Less commonCracked crankcase or gasket failureLess common, usually after impact damage or a very old, brittle gasket.

What to do

  1. Check the oil level with the engine off and cold, on level ground, and drain to the correct fill line if overfilled.
  2. Wipe the engine clean, run it briefly, then look closely to find exactly where oil is coming from.
  3. Check the drain plug for tightness and inspect its sealing washer, replacing it if crushed or missing.
  4. Make sure the machine has always been stored upright, not on its side, since tilting can push oil out through vents.
  5. Inspect around the base of the crankshaft (where the pump or shaft exits the engine) for seepage, which points to a worn seal.
  6. Clean up any oil residue so you can monitor whether the leak recurs after your fixes.
  7. A worn crankshaft seal requires partial engine disassembly and is best handled by a small-engine repair shop.

Tools and parts

  • Oil drain pan
  • Wrench for drain plug
Small engine oilSearch: “SAE 30 small engine oil”
Drain plug gasket/washerSearch: “engine oil drain plug washer”

When to call a pro

If oil is coming from the crankshaft seal or you see it inside the pump area, have a small-engine shop inspect and reseal it.

Safety

Generally low risk

Generally low risk for a careful person. Stop if anything looks different from what this guide describes.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.