How to Unblock a Pressure Washer Nozzle

A blocked nozzle is the most common reason a pressure washer suddenly feels weak, and the easiest fault on the whole machine to fix. Shut the machine off, release the trapped pressure in the lance, clear the orifice from the front with a nozzle pin, then flush it backwards with water. Five minutes, no tools beyond the wire pin that came in the box.

How to tell the nozzle is actually the problem

A blocked nozzle has a particular signature: the machine still sounds normal and the pump still builds pressure, but the spray pattern is wrong. Look for any of these.

• The fan pattern has a gap, a split, or fires off to one side instead of a clean even sheet.
• Water dribbles or fizzes out rather than leaving the tip in a firm jet.
• The motor cycles on and off more than usual, because pressure builds and cannot escape.
• Pressure feels fine with the nozzle removed from the lance but collapses once it is fitted.

That last check is the most useful one. Strong flow with the tip off but weak flow with it fitted means the blockage is in the nozzle. Weak flow either way points further upstream, usually the inlet filter, a kinked hose, or a supply that cannot keep up.

Make it safe first

Domestic machines run at roughly 100 to 160 bar, and there is still energy stored in the lance after you switch off. Work through this order every time.

1. Switch the machine off at the unit and pull the plug out, or stop the engine on a petrol model.
2. Turn off the water supply at the tap.
3. Squeeze the trigger with the lance pointed somewhere safe until the flow stops completely. This bleeds the residual pressure out.
4. Engage the trigger safety catch.
5. Only now remove the nozzle from the lance.

Never try to clear a tip while the machine is running or still pressurised. A jet from a partially blocked orifice can pierce skin, and the injury is a lot more serious than it first looks.

Clearing the blockage step by step

1. Use the nozzle cleaning pin

Nearly every washer ships with a thin stiff wire, often clipped to the handle or buried in the accessory bag. Insert it into the front of the opening and work it in and out a few times, keeping it straight rather than levering it sideways. If the pin is long gone, a strand from a wire brush or a fine sewing needle will do, as long as it slips in without force. Never open a tip with a drill bit.

2. Backflush with water

With the debris loosened, hold the nozzle under a running tap so the water enters from the rear and carries the grit out through the front. On a garden hose, press the tip against the hose end for twenty seconds or so. This is the step people skip, and it is the one that actually removes the material rather than just shifting it.

3. Soak stubborn deposits

If the blockage is limescale or dried detergent rather than a lump of grit, drop the nozzle in a cup of white vinegar for around thirty minutes, then repeat the pin and flush.

4. Check the seals while it is off

The small O ring behind the nozzle takes a beating. If it looks flattened, split, or has gone hard and shiny, replace it. A perished O ring lets water bypass the tip and gives exactly the weak spray you were trying to cure.

5. Refit and test

Push the nozzle home until the quick-connect collar clicks, then tug it to confirm it is locked. Reconnect the water, run the machine with the trigger open for a few seconds to purge air, and test the pattern on the ground before going near paintwork or render.

When cleaning does not fix it

Nozzles are consumables. The orifice is machined to a precise size, and grit passing through slowly erodes it. A worn tip gives a wide, soft, low-pressure spray that no amount of cleaning will restore, because the hole is simply too big now. If you have cleaned it properly and the pattern is still poor, the tip has had its life.

Turbo and rotary nozzles are a different case. They contain a spinning ceramic insert, and when that seizes you lose the rotation rather than the flow. Those are generally not serviceable and get replaced as a unit.

Stopping it happening again

• Fit and maintain the inlet filter. It exists specifically to stop grit reaching the pump and nozzle, and a clogged or missing one is the usual root cause.
• Never rest the lance tip in mud, gravel, or a puddle between passes. That is how most debris gets in.
• Flush clean water through after using detergent so nothing dries inside the tip.
• Store nozzles in the holder on the machine, not loose in a bucket of accessories.
• If you are drawing from a butt or tank rather than the mains, add an inline filter on the feed.

Ten seconds at pack-up time saves the whole routine above: trigger the lance to depressurise, wipe the tip, clip it back in its holder.