Description
S3Q2 238-8648 Diesel Engine Assembly Overview
The S3Q2 238-8648 Engine assembly manufactured by Tatan is a 1.813-liter inline 3-cylinder liquid-cooled industrial diesel powerplant belonging to our Diesel Engine Assembly classification. Engineered specifically for Caterpillar CAT 303.5, 303.5C CR, 303.5D, and 303.5E 3.5-ton mini excavators, replacing your worn or failed engine core with a Tatan complete turnkey assembly stops crankcase oil spitting, restores 23.6 kW (31.6 HP) rated output at 2400 RPM, and cures hot-idle oil pressure loss under continuous hydraulic pump load.
Coupled directly to the machine’s main hydraulic pump and governing the C0170 main control valve, this S3Q2 238-8648 Engine incorporates an induction-hardened forged steel crankshaft, an indirect injection swirl chamber cylinder head, an internal trochoid gear oil pump, and an in-line mechanical Bosch-type fuel injection pump, ensuring 100% direct bolt-on installation with flywheel housings and chassis mounts.
Key Attributes & Technical Parameters for S3Q2 238-8648 Engine
| Product Category | Diesel Engine Assembly | Warranty | 1 Year / 12 Months |
| Specific Valve Model | Mitsubishi S3Q2 / Cat C1.8 Diesel Engine | Brand Name | Tatan |
| Compatible Equipment | Caterpillar CAT 303.5 | 303.5C CR | 303.5D | OEM Part Number | 238-8648 / 283-1244 / 344-0504 |
| Matched Engine Series | Mitsubishi SQ Series (3-Cylinder Diesel) | Place of Origin | Guangdong, China |
| Max Relief Pressure | 22.4 kW – 23.6 kW @ 2400 RPM Rated | Pilot Control Pressure | 1.813 Liters (88mm × 99.5mm) |
| Spool Precision Spec | Micro-Honed STD 88mm Bore < 0.003 mm | Quality Status | 100% Brand New Turnkey Assembly |
| Machinery Test Report | Provided (100% Dyno Bench Tested) | Video Outgoing-Inspection | Provided Before Shipping |
| Hydraulic Fluid Spec | 15W-40 Heavy-Duty Diesel Engine Oil | Packaging | Export Wooden Box Packaging |
Multi-Machinery Fleet Support & Engine Assembly Inventory
Tatan supplies factory-built turnkey diesel engines, cooling packages, water pumps, and internal overhaul rebuild parts for excavators, wheel loaders, and compact rollers globally:

Supported Excavator Machinery Brands & Global Coverage
In addition to Caterpillar compact excavators, Tatan manufactures and supplies replacement complete diesel engines, short blocks, and overhaul parts across major equipment brands:

Application Scenarios & Buyer Value
When contractors search to compare Caterpillar 303.5 engine replacement cost and upgrade their machine with our S3Q2 238-8648 Engine, they secure measurable field reliability and lower cost per hour:
| Application Scenario | Value Delivered to Buyer |
|---|---|
| Caterpillar 303.5 Engine Repowering | 1:1 direct bolt-on installation eliminates starting delays and restores full 23.6 kW power for simultaneous trenching and dozer blading. |
| Compact Machinery Repair Workshops | Avoids the complex labor of block re-boring and injector pump calibration; installs as a pre-timed turnkey unit. |
| Urban Landscaping & Drainage Fleets | Heavy-duty forged pistons and multi-layer steel head gaskets withstand continuous hydraulic breaker hammer operations. |
| Equipment Parts Stockists | High-demand 1.8L 3-cylinder engine inventory packaged in solid export wooden crates ready for immediate global dispatch. |
S3Q2 238-8648 Engine OEM Diagnostic & Troubleshooting Guide
Use this technical guide to diagnose common Mitsubishi S3Q2 diesel engine symptoms on your Caterpillar 303.5 mini excavator:
| Engine Fault Symptom | Technical Cause Analysis | Tatan Factory-Grade Solution |
|---|---|---|
| 1. Hard cold starting with heavy white smoke | Worn mechanical in-line injection pump delivery valves dropping injection pressure, or faulty glow plugs causing unburned fuel vapor. | Replace with Tatan complete S3Q2 238-8648 Engine assembly fitted with brand-new factory-timed injection pump and pre-tested glow plugs. |
| 2. Coolant boiling & expansion tank bubbling | Combustion gas blown past cylinder head gasket between cylinders 2 and 3 due to localized thermal distortion in compact engine bays. | Install Tatan new engine with factory-torqued MLS head gasket and precision surface-milled parent block face. |
| 3. Heavy crankcase blow-by & oil spitting | 88mm cylinder bore micro-scoring or stuck top compression rings allowing combustion pressure into the oil pan. | Install Tatan new S3Q2 turnkey engine; flush radiator cooling fins and install fresh dual-element air filters. |
| 4. Oil pressure lamp flickers at hot idle (< 0.12 MPa) | Excessive crankshaft main journal bearing clearance or worn trochoid oil pump rotor losing delivery volume under operating heat. | Replace complete engine assembly to maintain factory oil pressure (> 0.35 MPa rated / > 0.15 MPa idle) and prevent crankshaft seizure. |
Transport Packaging & Certified Quality Assurance
Every Tatan diesel engine undergoes internal anti-corrosion fogging, heat-sealed plastic wrap, and solid timber export crating:


✈️ Express Air Courier
Partnered with DHL, FedEx, and UPS for 3-7 day priority delivery worldwide.
🚢 Sea Cargo Freight
LCL and FCL container ocean freight for bulk equipment parts replenishment.
📦 Export Wooden Crates
Solid fumigated timber cases lined with thick shockproof foam to prevent transit damage.
S3Q2 238-8648 Engine FAQ & Related Categories
* Note: Wholesale Reference Price Starts From $300.00. Please contact Gavin for a final customized quote.









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