General Pump Kit 311 Piston Oil Seal Kit 18mm ET/LH - 2490

Stop oil leaks fast

Extend your pressure washer pump's life with General Pump Kit 311—a precision-engineered 18mm piston oil seal kit designed specifically for General Pump ET Series and LH Series pumps.

General Pump Kit 311 is a purpose-built 18mm piston oil seal kit that restores proper oil retention in General Pump ET Series and LH Series pressure washer pumps, stopping leaks fast and extending the life of your equipment.

Why You'll Love General Pump Kit 311

This section focuses on what Kit 311 actually delivers in the real world-practical benefits that matter when your pump is leaking oil and a job is waiting.

• Fast fix for oil leaks – Worn piston oil seals are among the most common causes of oil seepage on triplex plunger pumps. Dropping in a fresh set of three seals from Kit 311 stops the leak at its source and gets your pressure washer back in service quickly.

• Protects your crankcase and pistons – The kit prevents crankcase contamination by creating a tight seal around each 18mm plunger rod. When oil stays clean and at the correct level, bearings, bushings, and crankshaft surfaces remain properly lubricated.

• Restores pump performance and reliability – Oil seal kits restore pressure washer pumps to optimal condition. Consistent oil volume reduces drag, controls heat buildup, and supports steady output pressure over long run times.

• Reduces downtime in the field or shop – Keeping a Kit 311 on hand means you can address oil leaks on ET and LH pumps immediately-no waiting on full rebuilds or shipping pumps back to a service center.

• Simple to install with basic tools – Experienced users or service technicians can complete the seal replacement without specialized equipment, making this a practical field or bench repair.

What Makes General Pump Kit 311 Different

Most generic seal assortments force you to sort through sizes and hope for a fit. General Pump Kit 311 is built differently:

• Engineered specifically for 18mm ET & LH pumps – Kit 311 fits ET Series and LH2126S pumps with 18mm pistons. The seals match the exact bore, lip profile, and housing dimensions these pumps require, eliminating guesswork and fitment problems.

• OEM-grade materials and profiles – The seals are constructed from oil- and heat-resistant elastomer with a reinforced lip design suited for high-pressure operation. This matters in both cold-water and hot-water applications where crankcase temperatures climb during extended use.

• Includes all three piston oil seals in one kit – General Pump Kit 311 includes three oil seals-one for each piston-so you replace the complete set at once instead of chasing individual failures later.

How General Pump Kit 311 Works

Here is a simplified overview of the replacement process and the sealing function Kit 311 performs on your General Pump.

1. Remove the pump from the pressure washer and access pistons Depressurize the system completely, shut off the motor, disconnect water lines, and drain the pump oil. Remove the crankcase cover or manifold housing to expose the three 18mm plunger rods.

2. Remove worn 18mm piston oil seals Carefully extract each old seal from around the piston rods. Inspect the plunger surfaces for scoring, pitting, or corrosion-damaged rods will compromise new seals and may require additional replacement parts.

3. Install new seals from Kit 311 Apply a light coating of oil or grease to each new seal, then press it into position with the sealing lip oriented correctly (typically facing the oil side of the crankcase). Repeat for all three pistons. Kit 311 is sized 18 mm x 24 mm x 4 mm, so correct usage of the kit involves inspecting seal compatibility with specific pump models before installation.

4. Reassemble, refill oil, and test Reinstall the manifold or crankcase cover, torque fasteners to specification, and fill with the recommended pump oil. Run the pump briefly at low pressure and visually inspect all seal areas for leaks before returning to full operation.

Product Details for General Pump Kit 311

A quick specification snapshot for fast reference:

• Type: Piston oil seal kit for General Pump pressure washer pumps

• Piston size: 18mm (matching 18mm bore plunger rods)

• Seal dimensions: 18 mm × 24 mm × 4 mm

• Compatible pump families: General Pump ET Series (including ET1505E34, ET1506E34, and related models) and LH Series (including LH2126S)

• Contents: 3 piston oil seals (one per cylinder); does not include water packings, valves, or other hardware

• Construction: Oil- and heat-resistant elastomer with reinforced lip design for high-pressure triplex plunger pumps

• Cross-reference numbers: 8.759-012.0, 87590120, RKI311, KIT311, GP-KIT-311, K311, GPKIT311

• Typical applications: Commercial and industrial cold-water and hot-water pressure washers, vehicle cleaning systems, and facility wash-down equipment using the specified General Pump models

Who General Pump Kit 311 Is For

Not sure if Kit 311 is the right product for your situation? Here is who benefits most:

• Facility maintenance and janitorial teams – Keep in-house pressure washers operational without scheduling outside service calls. Routine use of Kit 311 is standard practice for maintaining high-pressure triplex plunger pumps in daily wash-down operations.

• Pressure washing contractors – When your ET or LH pump rides on a trailer or skid and oil starts weeping mid-job, a Kit 311 in the toolbox means you finish the day instead of losing revenue.

• Rental yards and equipment dealers – Stocking this kit supports fast fleet turnarounds. Replacing worn seals helps extend pump life by preventing friction and wear, keeping rental units profitable longer.

• Service technicians and repair shops – Professionals rely on the correct 18mm seal kit to complete preventive rebuilds and warranty work efficiently. Scheduled maintenance includes replacing oil seals to prevent leaks before they escalate to internal damage.

If your General Pump uses 18mm pistons and the manual or parts breakdown references Kit 311, this is the correct piston oil seal kit for your pump.

Frequently Asked Questions About General Pump Kit 311

Common compatibility and installation questions answered:

How do I confirm that my pump uses Kit 311? Check the pump model plate for designations such as ET1505E34, ET1506E34, or LH2126S, then consult the owner's manual or parts breakdown. Look for "Kit 311," "Oil Seal Piston," or the 18mm piston specification. General Pump ET Series uses 18mm piston oil seal kits on models with an 18mm bore-verify bore size before ordering.

Does Kit 311 include water seals or valves? No. This is a piston oil seal kit only-it addresses oil-side sealing around the plunger rods. If your pump also needs water packings or valve replacement, separate kits (such as Kit 312, Kit 313, or Kit 309) are required for a full overhaul.

Can a DIY user install General Pump Kit 311? Experienced DIYers with basic mechanical skills and common hand tools can often handle the job. However, commercial or complex installations may benefit from a qualified technician to ensure correct seal orientation and proper torque on reassembly.

How often should piston oil seals be replaced? There is no universal hour count. Replace seals when you observe visible oil seepage around the crankcase, milky or discolored pump oil (indicating water intrusion), or as part of a scheduled preventive maintenance cycle during routine oil changes.

What happens if I keep running with worn oil seals? Oil loss leads to inadequate lubrication of bearings and crankshaft surfaces. Water contamination of the crankcase accelerates corrosion and wear. Left unchecked, these conditions can cause bearing failure, scored pistons, and a pump that requires far more expensive repairs than a simple seal kit.

Is Kit 311 suitable for hot water pressure washers? Yes, provided your pump model and 18mm piston specification match. The elastomer seals are designed to handle typical hot-water operating conditions, but system fluid temperatures must stay within the pump's design limits-commonly around 165 °F (74 °C) for ET Series pumps. The kit supports pumps used in pressure washing and vehicle cleaning systems across both cold and hot water setups.

Ready to Restore Your General Pump?

General Pump Kit 311 is the targeted, cost-effective way to stop oil leaks and protect the internals of your 18mm-piston ET and LH Series pressure washer pumps. Replacing all three seals at once restores proper crankcase sealing and helps you avoid the cascading damage that comes from running on worn components.

Need help choosing the right kit or walking through a repair? Contact the Barens team for expert advice on General Pump Kit 311 selection, compatibility questions, or step-by-step guidance. Reach out by phone or email-our team is ready to help before downtime costs you more than a simple seal swap.