How to Change a Pressure Washer Nozzle

Changing a pressure washer nozzle takes about ten seconds once you know the trick: shut the machine off, squeeze the trigger to bleed the trapped pressure, then pull back the collar on the end of the lance and the old nozzle drops straight out. Push the new one in until you hear it click and release the collar. The part everyone gets wrong is the pressure release, and that is also the part that hurts if you skip it.

First work out which fitting you have

Not all pressure washers use the same nozzle attachment, and the method changes depending on yours. There are three common types on domestic machines sold in the UK.

• Quick-connect (1/4 inch bayonet): a small spring-loaded collar sits at the tip of the lance. Nozzles are short colour-coded plugs. Most petrol machines and mid to high end electric ones use this.
• Twist lance: no separate nozzle at all. You rotate the end of the lance to move between a pencil jet and a wide fan. Nothing to remove, though the whole lance is usually swappable at the gun.
• Proprietary click-fit: Karcher and a few others use their own bayonet at the gun end. The whole lance twists off and a different lance clicks on. Third party adaptors exist if you want standard nozzles.

If you are unsure, look at the very tip. A visible metal collar you can slide back means quick-connect. A knurled ring you rotate means a twist lance.

Changing a quick-connect nozzle, step by step

1. Turn the machine off at the switch and, on a petrol unit, kill the engine. Do not just let it idle.
2. Turn off the water supply at the tap. Skipping this is why some people find the lance still under pressure.
3. Point the gun somewhere safe and squeeze the trigger. You will get a short spurt of water and then nothing. That means the line is depressurised.
4. Engage the trigger safety catch. Every gun has one, usually a small plastic tab that flips over the trigger.
5. Pull the collar back toward the gun and hold it. The nozzle will drop free, so cup your other hand under it or do this over a bench rather than a gravel drive.
6. Push the replacement nozzle in fully while the collar is still held back. It should seat with a definite stop, not a vague one.
7. Release the collar and tug the nozzle firmly. If it moves at all, it is not locked in. Repeat step six.

That tug test at the end matters more than it sounds. A nozzle that is not fully seated can be fired out of the lance at speed when you pull the trigger, which is both dangerous and an easy way to lose a nozzle in the hedge forever.

When the nozzle will not come out

Seized nozzles are usually down to limescale or grit that has worked its way into the collar mechanism. Before you start levering at it with pliers, try these in order:

• Confirm the system really is depressurised. Residual pressure holds the nozzle tight and is the single most common cause.
• Work the collar back and forth a dozen times to break up any grit sitting in the groove.
• Soak the tip end of the lance in warm water with a splash of white vinegar for twenty minutes to soften limescale, then try again.
• If it still resists, grip the nozzle body with pliers while holding the collar back, and pull straight out. Do not twist or waggle, as that damages the retaining balls inside the collar.

Once it is free, wipe the shank of the nozzle clean and put a smear of silicone grease on the O-ring before it goes back in. That alone prevents most future seizures.

Choosing the right nozzle for the job

Swapping the nozzle is the easy part. Picking the correct one is what actually protects the surface you are cleaning. The colours are a standard, not a manufacturer's whim.

• Red (0 degrees): a pencil jet. Rarely the right answer on anything around a house. It will scar concrete and shred timber.
• Yellow (15 degrees): stripping paint, heavy moss on hard concrete, stubborn stains.
• Green (25 degrees): the general purpose choice for patios, driveways and decking.
• White (40 degrees): gentle. Cars, render, windows, painted surfaces.
• Black (65 degrees, low pressure): the soap nozzle. Detergent will only draw through this one because it lowers the pressure enough for the injector to work.

If detergent is not coming out of your machine, nine times out of ten the black nozzle is simply not fitted. Nothing is broken.

Twist lances and Karcher-style fittings

On a twist lance there is nothing to swap. You rotate the collar to widen or narrow the fan and that is the full range available. The wear point is the internal seal, and when it fails you replace the lance rather than a nozzle.

For Karcher-type click-fits, the process is: kill the power, release the trigger pressure as above, push the lance in slightly toward the gun, twist roughly a quarter turn anticlockwise, and pull it away. The new lance goes on the same way in reverse. If it feels stiff, it is usually because you are trying to twist without pushing in first.

Habits worth keeping

Store nozzles in the holder on the machine rather than loose in a bucket, where they pick up grit that then goes straight into your pump seals. Flush the lance with clean water at the end of a job, especially after detergent. And glance at the orifice before each session: if the hole looks oval or ragged rather than round, the nozzle is worn and your pressure at the surface has already dropped.