Plunger 18mm L-97,6mm

The 18 mm plunger (piston) for an AP pump with length L = 97.6 mm is a working element of a high-pressure pump responsible for generating pressure in the pumping section. In industrial washer service, it is replaced when the working surface is worn, mechanically damaged, or during a full pump refurbishment.

MPN / reference: 410321
Weight: 0.19 kg
Dimensions / size: 1.8 × 9.7 × 1.8 cm (L ~ 97 mm)

APPLICATION

Used in high-pressure pump service work, including:

• replacing the plunger/piston in AP pumps used in industrial pressure washers,
• refurbishment of the pump working section after long operation,
• pump repair after seizure/scuffing or operation with improper water supply,
• overhaul when cooperating parts show wear (seals, guides/bushings).

SYMPTOMS - WHEN IT’S WORTH REPLACING

Typical signs of plunger wear or damage:

• drop in working pressure and reduced pump output,
• jet pulsation and unstable pressure maintenance (after ruling out nozzle/valves),
• leaks around the pump head caused by accelerated seal wear,
• unusual friction/noise from the working section, especially after operation with contaminated water,
• visible scratches, pitting, or damage on the plunger surface after disassembly.

HOW TO CHOOSE THE RIGHT PART

Selection must be precise, because the part works within tight tolerances with seals and guides:

• by manufacturer MPN / reference: 410321,
• by dimensions: 18 mm diameter and L = 97.6 mm,
• by comparison with the removed part: verify length, diameter, and the condition of cooperating surfaces.

Correct fit is critical for pump tightness and service life - an incorrect diameter/length can lead to fast seal wear or pressure loss.

COMPATIBILITY

Part described for AP pumps. Confirm selection by MPN 410321 and parameters 18 mm / L=97.6 mm using the pump documentation or parts list/spec table. Do not select only by “18 mm plunger” without verifying length and reference.

[faq]

Is 18 mm diameter alone enough to choose the correct plunger?|Not always. Besides diameter, the length (L=97.6 mm) and match to the pump design are key. The safest approach is selection by MPN 410321 and comparison with the removed part.
Do I need to replace seals when replacing the plunger?|In service practice, often yes-new and worn parts may not mate correctly (worn seals can quickly damage a new plunger and vice versa). Final decision depends on the condition of seals and guides after inspection.
Can I use an aftermarket plunger/piston?|Only with full dimensional match (18 mm and 97.6 mm), correct geometry, and appropriate surface quality. Tolerances are critical in pump working parts, so the reference point should be the MPN and pump specification.

[/faq]