Maintaining Your Pressure Washer’s Pump

Maintaining Your Pressure Washer’s Pump

Having problems with your Billy Goat pressure washer? Need to prepare it for winter storage? Here’s what you need to care for the pump on your equipment.

Identifying Your Pump

The new 4,000 PSI commercial grade gas pressure washer, model PW40S0H, uses a triplex pump from CAT Pumps, while all other Billy Goat models use a triplex pump from Annovi Reverberi (AR.) Both companies place a tag with the model information on the top of the pump that will be next to the brass plunger body or the base.

Before you start working on internal components, download a parts breakdown from the manufacturer’s site: these are complicated pieces of equipment with lots of small parts that need to be fitted correctly to produce pressure and prevent internal damage.

Caring for AR Pumps

These pumps are not rated for hot water, but this shouldn’t be an issue since these pressure washers are designed to be hooked up to a garden hose.

When storing, run a 50% solution of water and RV antifreeze or non-toxic, biodegradable antifreeze through the pump. This will protect it from freezing while keeping the seals and O-rings inside lubricated.

Caring for CAT Pumps

The crankcase of the pump needs to be filled with CAT Pump hydraulic oil. This oil should be replaced after the first 50 hours of operation, then every three months or 500 hours of use thereafter.

When storing, the pump should be flushed with a solution of 50% water and 50% antifreeze. CAT Pumps recommends hooking a four-foot length of hose to the inlet and starting the pump. Shut the pump off once the hose is empty. When it’s time to get the pressure washer out of storage, set the regulator to the lowest pressure point and hook up a hose. Let water flow through the pump for two or three minutes to flush out the antifreeze. Turn the crankshaft by hand to make sure it will spin freely before starting the engine. Gradually open up the regulator in small increments until it reaches the pressure you need instead of opening the valve all at once.

These pumps can handle hot water (over 130ºF,) but pumping performance will decrease.

Addressing Common Issues

Most low pressure and pulsation issues are due to problems outside of the pump. Before opening the pump for inspection, try the following:

— Clean the debris filters on the water inlet and chemical inlet.
— Remove any kinks in the supply hose.
— Check the outlet hose and spray wand for leaks.
— Check the nozzle for wear and damage.
— Make sure air isn’t getting mixed in with the water supply.
— Use a shorter supply hose to reduce flow resistance. Linking together several hoses to work in remote areas can result in flow rates below what the pump needs to operate.

Inspection and Repair

Most problems inside the pump stem from piston issues. Valve plugs on AR pumps are designed to be removed with a 22mm wrench while CAT pumps use an M24 hex tool. Inspect the O-rings and lift the pistons out of the pump using a pair of needle nose pliers. With the pistons out, push up and down on the poppet valve. It should move freely. Clean out any debris that has gathered on the valve.

CAT recommends using Loctite 242 on the plugs when fitting them back to the pump case. This threadlocker is formulated to prevent the plugs from unscrewing when subject to vibration while still allowing the plugs to be removed down the line.

If everything looks fine on the piston end, the issue will usually involve failed seals around the plungers. Before you attempt inspection or repair, you should have a rebuild kit on hand: both companies recommend replacing the O-rings and washers inside the plunger housings whenever they’re opened. The pump will need to be unbolted from the engine before these parts can be accessed. The plungers themselves are ceramic, making them brittle and prone to damage if not handled gently; they are designed to be twisted out by hand, not pulled out with tools.

Getting Parts for Triplex Pumps is a certified Billy Goat dealer which means we have OEM parts from Billy Goat and their manufacturing partners including AR and CAT. Our site has built-in parts diagrams so you can find the parts you need, and we also offer full rebuild kits if you need to overhaul your pump. We ship across the U.S. and Canada.

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