For marine operators and engineers who rely on the Mitsubishi S6A3 engine, the piston is one of the most critical components in the combustion chamber. It must withstand extreme cylinder pressures, intense thermal cycling, and continuous reciprocating motion – all while maintaining a perfect seal and efficient heat transfer. The 35A17-30101 aluminum piston is a premium, OEM-grade replacement engineered specifically for the S6A3 marine diesel engine, offering exceptional durability, precise dimensional accuracy, and a direct drop-in fit.
Available as a bare piston or as part of a complete overhaul kit, this piston is designed to meet Mitsubishi Heavy Industries' exacting standards. In this guide, we examine its advanced construction, compatible engine variants, common failure signs, professional installation best practices, and why Rsolid Engine Parts is the preferred global supplier for Mitsubishi marine components.
1. Structural Features & Advantages of the 35A17-30101 Piston
The 35A17-30101 is not a basic casting – it is a precision-engineered component incorporating several advanced design features to withstand the high-load demands of marine duty cycles:
Premium aluminium-silicon alloy with Alfin® oil gallery – Manufactured from a high-grade aluminium-silicon alloy featuring an Alfin® oil gallery (a bonded aluminium-cast iron insert). This design provides exceptional strength-to-weight ratio, excellent thermal conductivity, and superior scuff resistance. The Alfin® oil gallery actively circulates pressurised engine oil beneath the piston crown, dissipating combustion heat and reducing crown temperatures by as much as 25-30°C. This significantly extends fatigue life and prevents thermal cracking – a critical advantage for sustained high-load marine applications.
Optimised combustion bowl geometry – The piston crown features a precisely machined combustion bowl (dimension: 110.00 mm), carefully contoured to match the fuel spray pattern from Mitsubishi's fuel injection system. This geometry promotes complete air-fuel mixing, reducing soot formation and improving fuel efficiency.
Precision-ground ring grooves – The ring groove dimensions are manufactured to exacting tolerances: 1-2.9K, 2-2.45H, 3-5.00. This ensures optimal ring seating, minimises blow-by, and reduces oil consumption over the piston's service life.
Precision-engineered piston pin bore – The pin bore is precisely machined to 58.00 mm with a pin length of 124.00 mm, designed to accept a fully floating piston pin for smooth, low-friction operation and long-term durability.
Large bore design – With a diameter of 150.00 mm, the 35A17-30101 is engineered for the S6A3's 18.56-litre displacement, delivering the surface area required for optimal combustion and power output.
Surface treatment – The piston features an Alfin® oil gallery surface treatment, which enhances the bond between the aluminium piston body and the cast-iron ring carrier, ensuring long-term reliability under extreme thermal stress.
Precision-weight matched sets – Each piston is machined to strict weight tolerances within factory-matched sets, ensuring perfect dynamic balance across all six cylinders – particularly critical for generator sets requiring stable frequency output.
Operational benefits for marine engineers and vessel owners:
Reduced oil consumption – The optimised ring groove geometry and precision bore fit minimise oil bypass past the rings.
Improved fuel economy – Restored compression ratios and precise combustion bowl geometry translate to better thermal efficiency.
Extended overhaul intervals – With proper fuel, air filtration, and coolant maintenance, this piston reliably delivers long service life.
100% direct drop-in fit – Identical to the original Mitsubishi piston in all critical dimensions – no block machining required.
2. Compatible Engine Models & Typical Applications
The 35A17-30101 piston is specifically engineered for the Mitsubishi S6A3 series – a family of 6-cylinder, inline, 4-stroke, water-cooled diesel engines widely used in marine propulsion and auxiliary power roles.
| Engine Model | Typical Applications |
|---|
| Mitsubishi S6A3 | Main propulsion for fishing vessels, coastal freighters, harbour tugs |
| Mitsubishi S6A3-(T2)MTK3M | Marine propulsion, fishing boats, work boats, tugboats |
| Mitsubishi S6A3 (Genset variants) | Prime and standby power generation on vessels and offshore platforms |
Engine Specifications (S6A3-(T2)MTK3M):
Cylinder configuration: 6 in-line
Total displacement: 18.56 litres
Bore x stroke: 150 mm x 175 mm
Compression ratio: 14.5:1
Method of operation: 4-cycle, water-cooled, direct injection, turbocharged with air-cooler
Critical cross-reference: The 35A17-30101 is the genuine Mitsubishi service part number for standard-size pistons in the S6A3 series. It is closely related to 35A17-30100 – always confirm your engine serial number (e.g., S6A3-****) before ordering. This piston is typically supplied as a bare unit; piston rings, pin, and circlips are ordered separately or as part of a complete repair kit.
3. Common Failure Modes & Installation/Replacement Recommendations
Typical Warning Signs Your Piston Needs Replacement
Excessive blow-by – Pressurised gases escaping into the crankcase, causing oil mist from the breather tube and reduced engine power.
High oil consumption with blue exhaust – Continuous blue smoke at operating temperature indicates worn ring grooves or a scored skirt allowing oil to enter the combustion chamber.
Piston slap / metallic knocking – A hollow, metallic tapping noise, especially noticeable during cold starts, points to excessive piston-to-cylinder clearance due to skirt wear.
Loss of compression / hard starting – Difficulty starting the engine, rough idle, and reduced load-carrying capacity signal a cracked piston crown or severely worn rings.
Metal particles in the oil – Finding aluminium or iron debris in the oil filter or sump indicates a piston in the early stages of catastrophic failure.
Professional Installation Best Practices
Thorough cylinder bore inspection – Measure the cylinder liner bore at top, middle, and bottom positions using a dial bore gauge. Verify that the bore is within service limits. The piston-to-cylinder clearance for the S6A3 should be confirmed with your engine manual.
Piston ring end-gap verification – Install the new rings into the cylinder bore (without the piston) and measure the ring end gaps. If the gap is too small, carefully file the ends with a ring filing tool. Never file rings on a used piston.
Ring installation – Use a proper ring expander to fit the rings onto the piston. Never roll the rings over the piston skirt. Ensure the ring markings face upward. Stagger the ring gaps at 120° intervals.
Lubrication – Coat the piston skirt, rings, and cylinder bore with clean engine oil or a high-quality assembly lubricant. Lightly lubricate the piston pin and pin bore.
Connecting rod assembly – Attach the piston to the connecting rod using the piston pin. Install new circlips and ensure they are fully and securely seated.
Piston installation into cylinder – Use a high-quality ring compressor to uniformly compress all rings. Gently tap the piston into the cylinder bore using a soft-faced mallet. The piston should slide smoothly – if excessive force is required, stop and check for ring misalignment.
Connecting rod bolt torque – Tighten the connecting rod bolts to Mitsubishi's specified torque (consult your engine manual for exact values for S6A3).
Break-in procedure – After complete reassembly, start the engine and run at low idle (no load) for 15-20 minutes. Gradually apply load over the next 8-10 hours. Change the engine oil and filter after the initial break-in period.
4. Why Rsolid Engine Parts Is Your Preferred Global Supplier
Rsolid Engine Parts has been a trusted supplier of Mitsubishi, Yanmar, and Caterpillar diesel components for over 15 years, serving marine fleets, power plants, and workshops across six continents. Here is why the 35A17-30101 piston from Rsolid is the intelligent choice:
OEM-equivalent manufacturing – Produced to ISO 9001:2015 and IATF 16949 standards, using identical aluminium-silicon alloy, Alfin® oil gallery technology, and heat-treatment processes as genuine Mitsubishi service pistons.
100% dimensional inspection – Every piston is measured for diameter, ring groove height, pin bore size, and weight using advanced CMM equipment.
Complete repair kit options – We offer this piston as a bare unit, with premium ring sets, or as a full overhaul kit including pistons, rings, pins, circlips, and gaskets.
Global inventory and rapid dispatch – Strategically warehoused in Asia, Europe, and North America, ensuring 3-7 working day delivery to most international ports and airports.
Competitive wholesale pricing – Attractive volume discounts for workshops, fleet operators, and parts distributors.
Free expert technical support – Our in-house diesel engineers provide illustrated installation guides, torque specifications, and troubleshooting advice via WhatsApp or email.
Solid warranty – 12 months / 2,000 operating hours against casting defects, premature wear, and material failures.
Contact Rsolid Engine Parts Today
📧 Email: amy@rinjector.com
📱 WhatsApp: +86 15975376778
Whether you need a single 35A17-30101 piston for a running repair or a full set of six pistons for a complete Mitsubishi S6A3 overhaul, Amy and her team will provide a detailed quotation, stock confirmation, and shipping schedule within 2 hours. We also supply complementary parts – piston rings, cylinder liners, connecting rods, bearing shells, and gasket sets – for comprehensive engine rebuilds.
Choose the 35A17-30101 piston from Rsolid – engineered for uncompromising durability, reduced oil consumption, and reliable power for your Mitsubishi S6A3 marine engine.
