ISUZU D-MAX NLR85 Power Steering Pump 8-97355980-3 OEM Fit

The Power Steering Oil Pump Assembly with OEM numbers 8-97355980-3 and 8-97946698-0 is a verified direct-fit replacement for ISUZU D-MAX / NLR85 / NMR85 / TFR / TFS series pickups and light trucks equipped with 4JJ1 / 4JK1 / 4JJ1-TCS / 4JK1-TCS diesel engines. This steering pump is the core power source of the hydraulic power steering system, converting the engine's mechanical energy into hydraulic energy to deliver stable, continuous assistance to the steering gear — ensuring light and precise steering even at low speeds, under heavy loads, and in off-road conditions.

The power steering pump is driven by the engine via a belt or gear, draws steering fluid (ATF or dedicated power steering fluid) from the reservoir, pressurizes it, and delivers it to the steering gear. When the driver turns the steering wheel, the steering gear uses the hydraulic pressure to push the steering arm (or rack), turning the wheels.

This assembly employs a vane-type hydraulic pump design: the rotor and cam ring are eccentrically arranged, and the vanes — under centrifugal force and hydraulic pressure — press against the cam ring inner surface, creating cyclic changes in sealed volume for oil suction and delivery. The pump incorporates an internal flow control valve and a safety valve (relief valve), ensuring stable controlled flow across varying engine speeds and automatically relieving pressure when the system exceeds the preset limit, protecting the entire hydraulic assist system from overload damage.

This assembly features a 29-tooth drive gear (Z=29) that meshes directly with the engine timing gear train. The original drive type (gear vs. belt) and tooth count must be confirmed before installation.

Replace the power steering pump when any of these symptoms appear:

• Heavy or stiff steering — internal pump wear causes insufficient output pressure and flow, most noticeable at low speeds or idle.
• Whining or hissing noise during steering — worn internal bearings, sticking vanes, or air ingress in the system increase operating noise.
• Steering fluid leakage — aged pump seals (oil seals, O-rings) allow fluid to seep from the pump shaft or housing joints.
• Steering wheel vibration or pulsation — a faulty flow control valve or internal pressure fluctuations cause uneven steering feel.
• Darkened steering fluid or metal debris — severe internal pump wear contaminates the hydraulic system with metal particles, potentially damaging the steering gear further.
• Complete loss of assist — a broken pump shaft or seized internal mechanism eliminates hydraulic assistance, making steering extremely heavy.

1. Preparation: Disconnect the battery negative terminal. Place a drain pan under the steering pump. Remove the drive gear/belt.
2. Removal: Disconnect the inlet and outlet lines from the steering pump. Remove the pump mounting bolts and withdraw the old pump.
3. Inspection: Inspect the mounting bracket for cracks or deformation. Check the lines and fittings for damage or blockage. Inspect the drive gear/belt for wear. Confirm the new pump's drive gear tooth count (Z=29) matches the original.
4. Installation: Install the new pump onto the bracket and torque the mounting bolts to specification. Ensure correct gear mesh — never hammer. Connect the inlet and outlet lines.
5. Filling & Bleeding: Fill the reservoir with the specified new steering fluid. With the engine at idle, turn the steering wheel lock-to-lock several times to bleed air from the system. Check and top up the fluid level.
6. Leak Check: Inspect all fittings, the pump body, and lines for leaks.
7. Road Test: Perform a road test to verify proper steering assist, absence of abnormal noise, and no leaks.

• Every 10,000 km: Check steering fluid level and condition. Inspect the pump and lines for leaks.
• Every 40,000–50,000 km: Inspect drive gear/belt wear. Check the pump for abnormal noise during operation.
• Every 2 years: Replace the steering fluid and thoroughly flush the system.
• When steering feels heavy or abnormal noise is detected: Inspect pump pressure, flow, and system sealing immediately.

• Standard Packaging: Anti-rust oil + VCI film + neutral carton.
• Custom Packaging: Neutral box, color box, or customer-branded packaging.
• Suitable For: Steering system repair shops, ISUZU parts distributors, fleet maintenance centers.
• Supply Capacity: Stable batch supply with batch-level quality reports available.
• MOQ: 1–10 PCS.