KIT 2872/2548 PISTONS 18mm SXW

When your pressure washer starts losing pressure, pulsing at the nozzle, or leaking water from the pump head, the plungers are usually the first place to look. Ceramic plungers are the heart of every triplex pump. They reciprocate inside the pump cylinders thousands of times per minute, pushing water from the inlet side to the high-pressure outlet. Over time, the ceramic surface can chip, score, or crack from normal wear, cavitation, or running the pump without adequate water supply. When that happens, the plunger can no longer maintain a seal against the packing, and you lose pressure.

This KIT 2872/2548 is the factory replacement ceramic piston kit for AR (Annovi Reverberi) SXW series pumps with 18mm plungers. It includes the ceramic plungers and associated components needed to restore your pump to original performance specifications. Replacing worn plungers and seals is significantly cheaper than replacing the entire pump, and on a well-maintained machine, a plunger kit will restore full pressure and flow.

When to Replace Your Ceramic Plungers

Ceramic plungers do not wear out on a predictable schedule the way oil or spark plugs do. Their lifespan depends on water quality, operating hours, and how well the pump is maintained. Here are the signs that your plungers need attention:

• Pressure loss: The machine is not hitting its rated PSI even with a clean nozzle and proper water supply. If you have already checked the unloader valve and nozzle size, the plungers or packing are likely worn.
• Pulsing or surging: Inconsistent pressure at the nozzle, cycling between high and low, indicates that one or more cylinders are not sealing properly on the compression stroke.
• Water leaking from the pump head: Water dripping from around the plunger area means the packing seals have failed, often because the plunger surface is damaged and no longer providing a smooth sealing surface.
• Visible damage: If you pull the plungers and see chips, cracks, scoring, or rough spots on the ceramic surface, they need to be replaced. Even small imperfections will chew through new packing seals in days.
• Pump ran dry: Running a triplex pump without water supply, even briefly, generates extreme heat on the plungers and packing. If your pump ran dry, inspect the plungers immediately. Dry-run damage often looks like heat discoloration or glazing on the ceramic surface.

Product Specifications

• Kit Number: 2872/2548
• Plunger Diameter: 18mm
• Material: Ceramic
• Fits: AR (Annovi Reverberi) SXW series pumps
• Kit Contents: Complete piston/plunger set for full pump rebuild
• OEM Part: Factory AR replacement component

Why Ceramic Instead of Stainless Steel

Pressure washer pumps use either ceramic or stainless steel plungers. In the commercial pressure washing world, ceramic is the standard for several important reasons.

Surface hardness: Ceramic is significantly harder than stainless steel. A harder plunger surface resists scoring and maintains a smooth finish longer, which means the packing seals last longer and maintain a better seal.

Heat resistance: Ceramic handles the heat generated by high-speed reciprocation better than metal. This is especially important on machines that run for extended periods on commercial jobs.

Chemical compatibility: Ceramic is inert to the chemicals used in pressure washing. Sodium hypochlorite, oxalic acid, and alkaline cleaners will not react with or corrode a ceramic plunger the way they can attack some metal alloys.

Surface finish: The polished surface of a ceramic plunger provides a low-friction seal against the packing, reducing wear on both the plunger and the seals. This translates to longer intervals between rebuilds and more consistent pressure output.

How to Replace Ceramic Plungers

Plunger replacement is a job most mechanically inclined contractors can handle with basic tools. If you can change a spark plug and an oil filter, you can swap plungers. Here is the general process:

1. Relieve pressure. Turn off the machine, squeeze the trigger to release trapped pressure, and disconnect the high-pressure hose.
2. Remove the pump head. Unbolt the pump head (the manifold that connects the inlet and outlet ports to the cylinders). Note the bolt pattern and torque sequence for reassembly.
3. Pull the old plungers. The plungers slide out of their cylinders once the head is removed. Inspect each one for chips, cracks, or scoring. Even if only one is damaged, replace all three at the same time. Mixed old and new plungers will cause uneven wear.
4. Replace packing seals. Whenever you replace plungers, replace the packing seals at the same time. Old seals on new plungers will leak immediately because the old seals have conformed to the wear pattern of the old plungers.
5. Install new plungers. Lubricate the new plungers and seals with pump oil or silicone lubricant. Slide the plungers into the cylinders and reassemble the pump head.
6. Torque the head bolts. Follow the manufacturer's torque specification and tighten in a star pattern to ensure even clamping pressure across the head gasket.
7. Test. Reconnect water supply and high-pressure hose. Start the machine and check for leaks. Verify that pressure output matches the pump's rated specification.

Extending Plunger Life

A few simple maintenance habits will significantly extend the life of your ceramic plungers and reduce the frequency of rebuilds.

Never run the pump dry. This is the single most damaging thing you can do to a triplex pump. Always verify water supply is connected and flowing before starting the engine. Even 10 seconds of dry running can overheat the plungers and destroy the packing.

Use clean water. Sand, grit, and debris in your water supply act as abrasives on the plunger surface and packing seals. Use an inlet strainer or sediment filter on your water supply line. If you are pulling from a tank, make sure the tank is clean and the pickup tube has a filter.

Change pump oil regularly. Pump oil lubricates the crankshaft bearings and the lower end of the plunger assembly. Old, milky, or contaminated oil accelerates wear on every moving part in the pump. Change it every 200 to 500 hours of operation or whenever it looks milky, which indicates water contamination from a failed seal.

Winterize properly. If your machine will sit unused in freezing temperatures, run pump protectant through the system to displace water. Frozen water in the pump cylinders can crack ceramic plungers and split the pump head casting.

Related Products

• General Pump EZ4040G Replacement Pump – Complete replacement pump if your current pump is beyond rebuild.
• Browse All Pump Parts – Plunger kits, valve kits, oil seals, packing, and complete rebuild kits for AR and General Pump.

Frequently Asked Questions

How do I know which plunger kit fits my pump?

You need two pieces of information: your pump model number and the plunger diameter. This kit fits AR SXW series pumps with 18mm plungers. The model number is typically stamped on a plate on the pump body. If you are not sure, call us with your pump model and we will confirm the correct kit.

Should I replace all three plungers or just the damaged one?

Replace all three. Plungers wear together, and mixing old and new creates uneven compression across the cylinders. This causes pressure pulsing and accelerates wear on the new plunger and the remaining old ones.

Do I need to replace the packing seals at the same time?

Yes. Old packing seals have worn to match the surface profile of the old plungers. New plungers with old seals will leak. Always replace packing and plungers together for a proper seal.

How long do ceramic plungers last?

With proper maintenance and clean water supply, ceramic plungers can last 1,000 to 2,000+ hours of operation. Poor water quality, dry running, or running without adequate lubrication can reduce that dramatically.

Is this an OEM part?

Yes. This is a factory AR (Annovi Reverberi) replacement kit with the same specifications and materials as the original plungers installed in your pump at the factory.

In stock and ships same day from Sun Brite Supply in Gaithersburg, Maryland. We carry pump parts, rebuild kits, and complete replacement pumps for AR, General Pump, and other major pressure washer pump brands.