Hitachi ZAX130‑5A Expansion Tank – (Coolant Reservoir)

Description

Detail Information

1. Product Overview

The expansion tank (also known as the coolant reservoir or overflow tank) is a critical component of the ZAX130‑5A’s closed‑loop cooling system. Engineered to Hitachi’s original equipment specifications, this genuine OEM tank serves as the central hub for managing engine coolant volume and pressure. Its primary function is to capture and store excess coolant as it expands when hot, then return it to the radiator as the system cools down. This self‑regulating process maintains a consistent coolant level and prevents air from entering the system, ensuring stable engine temperatures and reliable long‑term performance.

2. Key Features & Benefits

• Genuine Hitachi OEM specification – Manufactured to Hitachi‘s original factory standards for the ZAX130‑5A, ZX130‑5A, and compatible 13‑ton class excavators. This is a brand‑new, factory‑spec component – not an aftermarket substitute. It is an essential component for coolant maintenance; if your expansion tank is cracked, leaking, or the cap seal is faulty, it will break the vacuum and allow air into the system, leading to overheating and accelerated component wear.

• Automatic air‑bleed design – The ZX‑5A series cooling system features a new‑generation expansion tank that automatically bleeds air from the cooling circuit. This prevents vapor pockets (air locks) from forming in the cylinder head, a common cause of localized overheating and engine damage. The self‑bleeding function also eliminates the need for manual bleeding after coolant changes or top‑ups.

• Prevents cavitation and cylinder head damage – By maintaining a completely sealed, air‑free cooling circuit, the expansion tank protects the engine from cavitation erosion – a phenomenon where collapsing vapor bubbles erode metal surfaces inside the water pump and cylinder head. This is especially critical for the ZAX130‑5A’s Isuzu 4JJ1 engine, which relies on consistent coolant flow and pressure for long‑term durability.

• Reduced coolant loss and maintenance frequency – The sealed expansion tank design means the cooling system no longer requires frequent coolant top‑ups. Coolant that expands and overflows is captured in the tank and automatically drawn back into the radiator as the engine cools, dramatically reducing fluid loss and service interruptions.

• Lowers engine operating temperature – The improved sealed cooling system, with the expansion tank at its core, has been shown to reduce engine water temperature by 4 to 7°C compared to previous open‑system designs. This lower operating temperature reduces thermal stress on the engine, extends component life, and improves overall fuel efficiency.

• Compatible with the ZAX130‑5A cooling system – The ZAX130‑5A cooling system has a total coolant capacity of 24 litres. The expansion tank is designed to work seamlessly with the radiator and coolant circuit, ensuring proper fluid circulation through the engine block and the radiator core. The system uses a sealed pressurised design, which requires the expansion tank cap to maintain the correct pressure rating.

• Direct bolt‑on replacement – Mounting points and hose connections match the original Hitachi specifications exactly. No modifications – your mechanic unbolts the old tank and bolts this one in.

• Pre‑shipment visual verification – Before packing, we send you detailed high‑resolution photographs of the actual unit. You approve shipment – we never ship blind.

• Fast delivery – 5–8 working days lead time from our Guangzhou warehouse. Monthly supply capacity of 300 units.

3. Applications

The genuine Hitachi expansion tank is a critical cooling system component for the ZAX130‑5A and compatible 13‑ton class excavators used across a wide range of job sites:

• Heavy construction & earthmoving – Highway excavation, foundation digging, and large‑scale site preparation place sustained high loads on the engine, generating significant heat. The expansion tank ensures the cooling system maintains consistent temperature and pressure, preventing overheating during extended shifts.

• Urban construction & utilities – Sidewalk repairs, water and gas line trenching, and small‑scale demolition often involve stop‑start operation in tight spaces. The expansion tank‘s sealed design prevents coolant loss during frequent engine shutdowns and restarts, ensuring the system remains fully primed and ready for the next work cycle.

• Quarrying & aggregates – Loading trucks and stockpile management in abrasive dust conditions. The sealed cooling system, with the expansion tank maintaining positive pressure, prevents dust and debris from being drawn into the coolant circuit through the overflow hose.

• Forestry & land clearing – Steep slopes, fallen timber, and uneven terrain place varying loads on the engine. The expansion tank maintains stable coolant volume across changing operating angles, preventing air ingestion during steep climbs or descents.

• Agriculture & land management – Drainage ditch cleaning, irrigation trenching, and land preparation. The robust construction of the expansion tank withstands the vibration and shock loads common in agricultural applications, ensuring reliable cooling system performance in demanding field conditions.

• Equipment rental fleet – 13‑ton excavators are frequently rented machines. A genuine new expansion tank provides predictable service life and eliminates the risk of cooling system failure due to cracked or degraded plastic components.

4. FAQ – Frequently Asked Questions

Q1: What is the difference between an expansion tank and a radiator?

A: The radiator is the primary heat exchanger that dissipates heat from the coolant to the air. The expansion tank is a separate reservoir that captures expanding coolant, maintains system pressure, and automatically returns coolant to the radiator as the system cools. They work together as a closed‑loop system.

Q2: Why does the ZAX130‑5A use a sealed expansion tank instead of an open overflow bottle?

A: The sealed expansion tank eliminates the need for the operator to check coolant levels and top up regularly. In an open system, coolant is lost to the atmosphere through evaporation and overflow. The sealed design returns expanded coolant to the radiator automatically, significantly reducing maintenance frequency and preventing coolant loss. It also prevents air from entering the system, which can cause cavitation and overheating.

Q3: What causes an expansion tank to fail?

A: Common failure modes include: cracking of the plastic housing due to heat cycling and vibration; failure of the pressure cap seal, which prevents the system from maintaining correct pressure; and blockage of the internal return passages. Cracks in the tank or a faulty cap will allow air to enter the system, leading to overheating and coolant loss. A visibly cracked or leaking expansion tank should be replaced immediately.

Q4: What is the coolant capacity of the ZAX130‑5A cooling system?

A: The ZAX130‑5A cooling system has a total capacity of 24 litres of coolant. When replacing the expansion tank, ensure the system is refilled with the correct coolant mixture as specified in the Hitachi operator’s manual.

Q5: How can I verify the tank is genuine before shipping?

A: Before packing, we send you clear, high‑resolution photographs of the actual unit – mounting points, hose connections, casting marks, and overall condition. You approve shipment only after reviewing these images. We never ship blind.

Q6: What is the warranty on this expansion tank?

A: The warranty period is 3 to 6 months depending on product details. We do not provide warranty service for genuine original parts. Our value is delivered up front: genuine Hitachi components, new‑condition tank, and pre‑shipment visual verification. For customers who require a warranty‑covered option, we can quote aftermarket alternatives – ask our sales team.

Q7: How long does delivery take?

A: Delivery is 5–8 working days after order confirmation from our Guangzhou warehouse. Express shipping (DHL/FedEx/UPS) is available for urgent orders.

Q8: What payment methods do you accept?

A: We accept L/C, T/T, XTransfer, PayPal, and Western Union.

Still have questions? Contact Hongtengda Parts – we reply within 24 hours.