303.5D or 303ECR losing hydraulic pressure or pump making noise at full working speed? A worn 284-8038 main pump allows mini excavator bypass to grow until the compact machine can no longer maintain circuit pressure for bucket curl and arm crowd simultaneously. RITO supplies this Japan OEM-quality main pump to restore full 303.5D-series hydraulic output.
Item NO.:
284-8038Order(MOQ):
1pcsPayment:
T/T, WESTERN UNION, CHINESE BANK,PAYPALProduct Origin:
JAPANShipping Port:
Huangpu,GuangzhouLead Time：
In Stock284-8038 Hydraulic Main Pump Assembly for Caterpillar 303.5D, 303.5E, 303ECR and 304D mini excavators. Japan OEM quality. Variable axial piston pump engineered for the compact high-pressure demands of the Cat 303-304 mini excavator class. Factory-calibrated regulator and matched valve plate restore rated displacement and fast pressure response.
| Part Number | 284-8038 |
|---|---|
| Part Name | Hydraulic Main Pump Assembly (Japan OEM) |
| Compatible Brand | Caterpillar |
| Applicable Models | 303.5D, 303.5E, 303ECR, 304D Excavator |
| Application | Main variable axial piston pump for Caterpillar 303.5D / 303ECR mini excavator |
| Material | Japan OEM-grade precision alloy steel rotating group and housing |
| Product Color | Industrial finish |
| Working Temperature | -25°C~+60°C |
| Key Function | Generates main hydraulic system flow and pressure for Cat 303.5D-304D mini excavator work functions |
| Condition | 100% New Japan OEM Quality |
| Packaging | Wooden Case Reinforced Carton Neutral Packing Customized Box |
Key rotating group components sourced from Japan OEM precision manufacturers, providing dimensional accuracy and material hardness consistent with Caterpillar 303.5D-series OEM pump specification.
Compact rotating group and housing geometry rated for 303.5D-series maximum system pressure despite the small displacement envelope of the mini excavator pump class.
Regulator calibrated to 303.5D engine power specification, preventing engine overload during full hydraulic demand on the compact three-cylinder engine.
284-8038 covers 303.5D, 303.5E, 303ECR and 304D - the full Cat 303-304 compact mini excavator range.
FAQ
Q: What symptoms indicate the 284-8038 pump is failing on a 303.5D?
A: All functions slow simultaneously despite normal engine speed, bucket curl and arm crowd cannot be maintained together at working speed, pump case drain above OEM spec on a flow test, and hydraulic oil overheats faster than normal.
Q: What is the Japan OEM quality advantage for 284-8038?
A: Japan OEM-sourced key components provide dimensional accuracy and metallurgical quality consistent with Japanese pump manufacturing standards, offering higher precision than generic aftermarket alternatives for the demanding 303.5D mini excavator application.
Q: What break-in procedure applies to the new 284-8038 pump on a 303.5D?
A: Run at low pressure for 30 minutes after installation, checking for leaks. Then operate at half-load for 15 minutes before applying full working load. Replace the return filter element at 50 hours.
Q: How to confirm 284-8038 fits my 303.5D?
A: Match part number 284-8038 and confirm machine model is 303.5D, 303.5E, 303ECR or 304D. Provide machine serial number for cross-reference.
Q: What quality options are available?
A: We provide original, OEM and high-quality aftermarket versions with stable supply capability.
Q:Why Choose RITO?
A:Listed Factory
Stable&Reliable Quality
OEM Factory for Chinese Top Excavator Brands
Supplier to Fortune 500 Companies
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