CAT Pumps 44676 Pinion Oil Seal G1-G8 Heat Resistant - 2329

OEM NBR Seal That Prevents Oil Leaks Around the Pinion Shaft

The Cat Pumps 44676 is a genuine OEM pinion oil seal made from heat-resistant NBR (nitrile rubber), designed to fit Cat Pumps G1 to G8 gearboxes. It is compatible with gearbox models 8051, 8058, and 8061, among other G-series configurations. The seal sits in the gearbox housing around the rotating pinion shaft, where it prevents oil leakage and contamination while protecting the pinion bearing and gear teeth from premature wear. This page covers what the 44676 seal does, which equipment uses it, how to replace it, and how to keep it working for as long as possible.

Why You'll Value the Cat Pumps 44676 Pinion Oil Seal

A worn or cracked pinion oil seal turns a reliable Cat Pump gearbox into a leaking liability. Here is what a properly installed 44676 delivers:

• Stops Gearbox Oil Leaks – The 44676 seal keeps 80–90 weight gear lube inside the gearbox housing, eliminating drips onto the engine, frame, or floor. No more oil accumulation under the drive end of the pump.

• Protects Gears and Bearings – The seal helps protect the pinion bearing and gear teeth by maintaining the oil bath that keeps those components lubricated. Without adequate oil, gear scoring and bearing failure follow.

• Handles Elevated Temperatures – The CAT Pump 44676 Oil Seal is heat resistant. Cat Pumps gearboxes can run at crankcase temperatures of 120–180 °F depending on RPM and load. The NBR compound is rated for continuous service in that range, making it suitable for hot-water washing rigs and outdoor industrial operation in summer conditions.

• Low-Cost Maintenance, High-Value Protection – One seal per gearbox (quantity: 1) costs a fraction of a bearing or pinion gear replacement. Replacing a worn seal before it fails avoids cascading damage to internal components.

• Supports Quiet Operation and Consistent Pump Performance – When gearbox oil stays at the correct level, gear meshing remains smooth and quiet. Oil loss from a failed seal raises noise, increases friction, and can reduce discharge flow consistency.

What Makes the 44676 Pinion Oil Seal Different from Generic Alternatives

Generic oil seals may share the same nominal dimensions as the 44676 but differ in the details that determine service life. The Cat Pumps OEM seal is purpose-built for these gearboxes in three specific ways:

• Profiled for G1–G8 Gearbox Bore and Shaft Dimensions – The outer diameter, inner lip geometry, and thickness match the housing bore and pinion shaft used in Cat Pumps G1 through G8 gearboxes. A generic seal with looser dimensional tolerances can leak from day one or shift under thermal cycling.

• NBR Compound Selected for Gear Lube Compatibility – Cat Pumps specifies Medium Nitrile (Buna-N) for the 44676 because it resists swelling and hardening in 80–90 weight gear lube. Lower-grade elastomers may swell in oil service, lose lip tension, and start leaking within weeks.

• Lip Pressure and Spring Retention Matched to Operating Conditions – The garter spring and lip interference fit maintain consistent contact with the pinion shaft across temperature swings from cold startup to sustained operation at 150 °F or higher. Generic seals with incorrect durometer or spring tension lose contact as temperatures rise, allowing oil to weep past the lip.

How the Cat Pumps 44676 Pinion Oil Seal Works

The 44676 is a radial shaft seal. It sits between the gearbox housing and the rotating pinion shaft, creating a barrier that keeps gear lube on the inside and debris on the outside.

1. Seating in the Gearbox Housing – The seal's outer diameter press-fits into the bore of the gearbox housing or bearing cover. Once seated, the metal case of the seal locks into the bore and cannot rotate.

2. Sealing Against the Pinion Shaft – The inner sealing lip wraps around the pinion shaft. A garter spring behind the lip maintains inward pressure so the lip stays in contact with the shaft surface during operation. Install new pinion oil seal with the garter spring facing down (toward the oil side) so the lip pressure acts against the gear lube.

3. Containing Gear Lube While Excluding Contaminants – During operation, the oil-side lip retains lubricant under the slight pressure generated by gear rotation. The dust-side lip on the external face blocks water, grit, and spray from entering the gearbox cavity.

Product Details: Cat Pumps 44676 Pinion Oil Seal

• Part Number: 2329

• Application: Pinion shaft oil seal for Cat Pumps G1–G8 gearboxes, including models 8051, 8058, and 8061 as well as other G-series gear drive configurations such as the 8065 and 8068

• Material: Heat-resistant NBR (Medium Nitrile, Buna-N), formulated for gear oil service

• Function: Radial shaft seal that retains gearbox oil and blocks external contaminants at the pinion shaft

• Orientation: Oil-side lip faces the gearbox interior; dust lip faces the external environment

• Compatible Lubricants: 80–90 weight gear lube (Cat Pumps PN 6110) and other standard gear lubes specified in the pump service manual

• Quantity per Gearbox: 1

• Associated Components: Pinion gear, pinion bearing, bearing cover, internal retaining ring, and gearbox housing; refer to Cat Pumps exploded-view drawings for your specific model

Who the 44676 Pinion Oil Seal Is For

• Owners of Cat Pumps with G1–G8 Gearbox Drives – If your system runs a 45G1, 56G1, 60G1, 700G1, or similar configuration and uses a gearbox model like 8051, 8058, or 8061, this seal fits your pinion shaft. Examine the model tag on your gearbox housing and cross-reference the parts list before ordering.

• Maintenance and Service Technicians – Technicians responsible for gearbox inspections, leak diagnosis, and scheduled servicing will use the 44676 during routine oil changes or whenever a leaking pinion area is identified.

• OEMs and System Builders – Companies integrating Cat Pumps gear drives into pressure washing rigs, industrial cleaning skids, or process water systems need OEM-spec sealing components to deliver equipment that meets Cat Pumps specifications out of the box.

• Facilities Running High-Duty or High-Temperature Equipment – Plants where pumps operate for extended hours in warm ambient conditions benefit from a heat-resistant NBR seal rated for the temperatures that Cat Pumps gearboxes reach under load.

Replacing the 44676 Pinion Oil Seal

All gearbox work should be performed by trained personnel following the Cat Pumps pump service manual and applicable safety procedures.

Preparation and Safety

Lock out and tag out the power source. Depressurize the system. Drain lube from the gearbox housing before servicing. Clean the exterior of the gearbox to prevent debris from entering during disassembly.

Accessing the Pinion Assembly

Remove four screws to separate gearbox from the engine. Depending on your installation, you may also need to separate the gearbox from the pump crankcase. Once detached, remove the internal retaining ring, then withdraw the pinion gear and bearing to expose the seal.

Removing the Old Seal

Pry out the pinion oil seal with a screwdriver. Work carefully to avoid scratching the bore surface or the pinion shaft. The 44676 seal should be replaced if there is excessive shaft wear or scoring; inspect the shaft at this stage and note any damage.

Installing the New 44676 Seal

The seal should be lubricated before installation; apply a thin film of clean gear oil to the sealing lip and outer case. Press the new seal squarely into the bore using a seal driver or flat press plate. Install new pinion oil seal with the garter spring facing down, toward the gearbox interior. Avoid dragging the lip across sharp keyway edges or burrs on the shaft.

Reassembly and Testing

Refit the pinion bearing, pinion gear, retaining ring, and bearing cover. Torque screws to specifications when reassembling gearbox, per the values in your Cat Pumps service documentation. Fill gearbox housing with 80–90 weight gear lube after servicing, bringing the level to the oil gauge dot. Run the pump briefly and check for any sign of leaking around the pinion area.

Keeping the Seal and Gearbox in Service Longer

Proper installation techniques are critical to seal performance, but what happens after installation matters just as much.

• Check for Leaks Regularly – Routine visual checks for dampness or oil accumulation are recommended for maintenance. Look at the drive end of the gearbox around the pinion housing during every scheduled stop. Regular inspection can help monitor oil levels and detect leaks before they cause oil starvation.

• Maintain Oil Level and Quality – Cat Pumps recommends changing gearbox oil after the first 50 hours of operation, then every 500 hours. Using the recommended lubricant is crucial for proper seal performance. If the oil appears milky (water intrusion), dark (overheating), or contains metallic debris, change it and inspect the seal and bearings.

• Protect the Shaft Surface – When you disassemble the gearbox for any reason, wrap the pinion shaft keyway with tape or use a shaft sleeve to prevent nicks. A single scratch across the sealing zone will cut the lip and cause a leak that no adjustment can fix.

• Control Operating Temperature – NBR reaches its service limit around 200 °F (93 °C). Ensure adequate airflow around the gearbox. If your application consistently pushes gearbox temperatures above Cat Pumps' published limits, consult Cat Pumps about alternative seal materials such as FPM (Viton) or PTFE.

• Follow Cat Pumps Service Intervals – Adhering to the intervals in your pump service manual catches worn seals before they fail. In well-maintained systems using the correct oil at normal temperatures, the 44676 seal can reach 1,500 hours or more of operation.

Frequently Asked Questions about the Cat Pumps 44676 Pinion Oil Seal

Which Cat Pumps gearboxes use the 44676 pinion oil seal? The 44676 fits Cat Pumps G1 to G8 gearboxes and is listed in the parts drawings for models 8051, 8058, 8061, 8065, and 8068. Always verify the part number against your gearbox nameplate and the Cat Pumps parts list for your specific model.

Can I use a generic seal instead of the 44676? Generic seals may fit physically but often differ in NBR compound grade, lip geometry, and dimensional precision. Those differences can lead to early leaking, oil loss, and damaged bearings or gears. For maximum service life and reliable sealing, the Cat Pumps OEM part is the safer choice.

What are common signs that the pinion oil seal needs replacement? Visible oil around the pinion area, a dropping oil level in the gearbox, unusual gearbox noise from low lubrication, or milky/contaminated oil are all indications that the seal may be worn or damaged. The 44676 seal should also be replaced if there is excessive shaft wear or scoring observed during inspection.

Do I need special tools to replace the seal? Standard seal drivers and a flat-blade screwdriver for extraction are typically sufficient. No proprietary Cat Pumps extraction tool is required. Refer to the Cat Pumps service documentation for your gearbox model for fastener sizes and torque specifications.

How often should the 44676 seal be inspected? Inspect the seal area during every scheduled gearbox service and any time you remove the gearbox for other maintenance. If the pump operates in dusty, wet, or high-temperature conditions, increase inspection frequency.

Is the 44676 suitable for high-temperature industrial use? Yes. The heat-resistant NBR material handles the operating temperatures Cat Pumps gearboxes produce under normal and heavy-duty conditions (typically 120–180 °F). For sustained temperatures above 200 °F, contact Cat Pumps about high-temperature seal material options.

Restore Leak-Free Gearbox Operation

The Cat Pumps 44676 pinion oil seal is a single, low-cost NBR component that stands between reliable gearbox operation and oil loss, bearing damage, and unplanned downtime. Confirm your gearbox model, verify part number 44676 against the Cat Pumps parts list, and replace the seal before a small drip becomes an expensive repair. Add the 44676 to your next maintenance order and keep your Cat Pumps system running the way it was designed to.