Bomba Hidráulica Principal Hitachi EX400 / EX400-1 – Remanufaturada na China (4622371 / 4246412)

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The 40‑Ton Dilemma: Repair, Replace, or Gamble?

You have an EX400 or EX400‑1 that has lost its edge. The boom rises slower than it used to. The swing hesitates. The oil runs hot. The mechanic says “the pump is tired.” Now you face the same decision every owner of an older 40‑ton machine faces:

• Buy new genuine – Safe, but the price tag could buy a small car. Hard to justify on a machine that already has 10,000+ hours.

• Buy a used pump – Cheap upfront, but you have no idea how many hours are on it, whether it was run with contaminated oil, or if its bearings are already pitting. You are buying someone else‘s hidden failure.

• Send your pump for “repair” – Usually means a set of seals and paint. It will leak again in 500 hours.

• Choose a proper remanufactured pump – This is where the smart money goes. But only if the reman process actually replaces the right parts.

Let’s talk about what “remanufactured” actually means – and why most shops get it wrong.

The Myth of “Re‑sealed”

Many hydraulic shops offer “rebuilt” pumps. They disassemble, clean, replace O‑rings and shaft seals, slap on new paint, and call it done. The problem? The cylinder block and valve plate are still worn. The bearings are still fatigued. The piston slippers are still scored. Within 500–1,000 hours, internal leakage returns, oil temperature climbs, and you lose power again. You paid for a band‑aid, not a fix.

Our remanufacturing process is different because we start from a simple truth: worn metal does not un‑wear itself. You must replace it.

What We Actually Replace (Not Just Clean)

When we remanufacture your EX400/EX400‑1 pump (OEM 4622371 / 4246412), every single one of these components is inspected and almost always replaced:

That is a full restoration, not a cosmetic refresh.

The Real Test: Not a Spinning Shaft, But a Loaded Dyno Run

Any pump can turn by hand. A proper reman pump must prove itself under full working pressure. After reassembly, every EX400 pump we reman goes onto a hydraulic test stand and runs through a complete test cycle:

• Pressure ramp to 34.3 MPa (4,975 psi)

• Flow measurement at rated speed

• Case drain leakage check (internal wear indicator)

• Load‑sensing response time

• Pressure cut‑off verification

You get a test report with actual numbers. No guessing. No “feels strong.” You see the data before you pay.

Why This Matters for Your EX400 / EX400‑1

Your machine weighs 40 tons. It moves thousands of cubic meters of material every day. When the main pump loses just 10% of its efficiency, you lose:

• 10–15% in cycle time – slower loading, fewer trucks per hour

• Higher fuel burn – the engine works harder to compensate for internal leakage

• Overheated oil – wasted energy turns into heat, cooking seals and hoses

• Unpredictable failures – a tired pump does not die slowly; it fails suddenly

A proper reman pump restores original flow, pressure, and efficiency. Your EX400 digs like it did 8,000 hours ago. Not “almost.” Not “good enough.” Exactly.

The Simple Offer

We keep remanufactured EX400/EX400‑1 pumps (4622371 / 4246412) on the shelf in our Guangzhou warehouse. Not a core that we hope to rebuild next month. A finished unit, tested, painted, capped, and ready to bolt on.

What you get:

• A pump restored to OEM performance standards

• New bearings, new seals, re‑ground wear surfaces

• Hydraulic test report upon request

• Heavy‑duty wooden case, fumigation‑free, export ready

• 5–8 working days to most global destinations

What you do not get:

• A used pump with fresh paint

• “As‑is” gamble

• A 500‑hour band‑aid

Before You Order – One Photo, One Serial Number

Because EX400 and EX400‑1 have minor variations (different regulator settings, different port orientations), we need two things from you:

1. Número de série da máquina (starts with EX400 or EX400‑1)

2. A clear photo of the old pump’s nameplate (showing the OEM part number, even if faded)

We will confirm exact fitment and send you a firm quote within 24 hours. No guesswork. No “this should fit.”

Installation in plain language:
– The small drain line from the pump to the tank must be open. If it is pinched or blocked, pressure will build inside the pump and blow the main shaft seal the first time you start the engine.
– Before you bolt the new pump on, change all hydraulic filters and flush the tank if the old pump failed catastrophically (metal in oil). Debris kills a reman pump just as fast as a new one.
– Use new copper washers or O‑rings on every hose connection. Old seals will leak.
– After installation, idle the engine for a few minutes and slowly move each lever (boom, arm, bucket, swing, travel) to get the air out of the system. The machine may be sluggish at first – that is normal.

Warranty – honest and upfront:
O período de garantia é de 3 a 6 meses, dependendo dos detalhes do produto. We do not provide warranty for original used or remanufactured parts. We believe in doing the job right before we ship, not promising to fix it later. Our value is in the work – new parts, precise assembly, full testing, and photos before dispatch. If you need a traditional warranty, ask us about new aftermarket options.

Your EX400 or EX400‑1 has years of work left in it. The main pump should not be the reason you park it. Send us your machine details – we will get you a reman pump that actually works.