DONGFANG Cylinder Head | Replacement Spare Parts Compatible with Daihatsu Marine Diesel Engines

Compatible Models: DL-20、DL-22、DL-26、DL-28、DL-32、5DK-20、6DK-20、DK-28、DS-26、PS-26H (D)、DC-17、DE-18

I. Product Overview
DONGFANG cylinder heads are third-party replacement spare parts independently developed and manufactured by DONGFANG, suitable for maintenance applications of Daihatsu marine diesel engines and industrial diesel power systems.
The cylinder head is a core structural component of the diesel engine combustion chamber. It is installed on the upper part of the cylinder block and works together with the piston and cylinder liner to form a sealed combustion space. During long-term operation, the cylinder head continuously withstands high-temperature and high-pressure combustion, cyclic thermal loads, and mechanical vibration. The structural strength, sealing capability, and machining accuracy of the component directly determine the operating efficiency and service life of the entire power equipment.
Daihatsu Diesel series engines are widely used in marine propulsion units, marine auxiliary engines, and diesel generator sets due to their stable operation and excellent durability, making them suitable for long-term continuous operation. Marine and industrial power equipment often operate under high loads for extended periods in complex environments, which places high requirements on the thermal fatigue resistance and structural stability of replacement cylinder heads.
DONGFANG cylinder heads are developed through measurement and mapping based on the original structures of corresponding engine models, mold development, and are manufactured using precision casting, heat treatment, and CNC precision machining processes. The product’s assembly dimensions, sealing performance, and operating stability meet the maintenance and replacement requirements of power equipment, providing reliable maintenance spare part solutions for shipbuilding and repair companies, diesel engine parts distributors, and industrial power equipment users.

II. Applicable Engine Models
DONGFANG cylinder heads can match multiple Daihatsu diesel engine models and serve maintenance applications for marine power systems, marine auxiliary engines, and industrial diesel engines.
Applicable model list:
DL-20, DL-22, DL-26, DL-28, DL-32, 5DK-20, 6DK-20, DK-28, DS-26, PS-26H (D), DC-17, DE-18
Applicable equipment categories:
•Marine main propulsion diesel engine units
•Marine auxiliary power generation systems
•Stationary industrial diesel power equipment
Different engine models have differences in combustion chamber structures, valve arrangements, fuel injection systems, and cooling water passage designs. During product development, DONGFANG optimizes the products according to the structural differences of each model to ensure accurate assembly dimensions, precise valve installation positions, qualified injector hole machining, and stable combustion chamber sealing.
Customers can provide the engine model, original part number, or physical photos, and DONGFANG will assist in verifying the matching solution.

III. Main Functions of Cylinder Head
1. Withstand Combustion Pressure and Maintain Stable Power Output
The cylinder head withstands the high-temperature and high-pressure gases generated by fuel combustion and forms an effective seal with the cylinder liner. It maintains stable working pressure inside the combustion chamber, prevents gas leakage, improves compression efficiency, and ensures continuous power output of the engine unit. For diesel units requiring uninterrupted operation, reliable sealing is a fundamental condition for stable operation.
2. Control Intake and Exhaust Circulation to Improve Combustion Efficiency
The cylinder head integrates intake passages, exhaust passages, valve seats, and valve guides. Optimized air passage structures improve gas exchange efficiency, promote complete fuel combustion, and reduce energy loss.
3. Support Fuel Injection Components
The injector mounting base is precision-machined to firmly support fuel injection components, ensuring accurate injector positioning and stable injection conditions. It enables uniform combustion and reduces abnormal component wear.
4. Dissipate Combustion Heat and Reduce Thermal Load Damage
Marine diesel engines generally operate continuously for long periods, and heat dissipation performance directly affects the service life of the entire engine. The cooling water chamber inside the cylinder head continuously removes heat from the combustion area, reduces thermal stress around the combustion chamber, valve area, and injector, and minimizes problems such as thermal cracks, valve seat damage, and cylinder head deformation caused by long-term high-temperature operation.

IV. Optional Material Solutions
Based on different engine models, operating loads, and application environments, DONGFANG provides two mature material options:
1. High-Strength Alloy Gray Cast Iron
It features stable casting performance, good machinability, qualified thermal fatigue resistance, and outstanding cost performance.
Applicable scenarios:
Marine auxiliary engines, small and medium-sized marine power units, and conventional diesel generator sets.
2. Compacted Graphite Iron (CGI)
It provides higher mechanical strength, better thermal crack resistance, and improved fatigue durability.
Applicable scenarios:
Marine main engines operating continuously for long periods and high-load industrial diesel power equipment.

V. Manufacturing Process
1. Resin Sand Precision Casting
Complex internal structures such as cooling water passages, intake and exhaust passages, and combustion chambers are formed as an integrated structure, reducing casting defects such as pores and shrinkage cavities.
2. Artificial Aging Heat Treatment
It eliminates internal stresses generated during casting, improves dimensional stability under long-term high-temperature operating conditions, and reduces the possibility of thermal deformation.
3. CNC Precision Machining
The fire deck surface, valve mounting holes, injector holes, and mounting bolt holes are precision-machined. Critical dimensions are matched according to engine assembly requirements.
4. Surface Anti-Corrosion Treatment and Full Process Inspection
Products receive anti-rust surface treatment. Each unit undergoes dimensional inspection, water pressure resistance testing, and air-tightness testing in sequence, allowing adaptation to high-humidity and high-salt corrosion marine environments and ensuring long-term reliable sealing performance.

VI. Common Failure Reference
1. Thermal Cracks on Combustion Surface
Long-term high-load operation, poor cooling system conditions, and concentrated cyclic thermal stress may cause thermal cracks, which can lead to power reduction, insufficient compression pressure, and abnormal coolant consumption.
2. Valve Seat Wear and Burning
Continuous exposure of valves to high-temperature impact may reduce sealing performance, lower combustion efficiency, and cause engine unit vibration.
3. Cooling Water Chamber Corrosion
Marine salt content and coolant quality issues may cause water passage corrosion, leakage, and reduced heat dissipation capability.
4. Injector Position Sealing Failure
Long-term alternating pressure changes may result in fuel leakage, increased carbon deposits, and difficult engine starting.
VII. Advantages of Choosing DONGFANG Cylinder Heads
1. Developed Based on Original Engine Structures to Meet Maintenance Replacement Requirements
Product dimensions are verified through measurement and mapping, providing good assembly compatibility, reducing on-site adjustment workload, and supporting fast maintenance replacement.
2. Optimized Performance for Long-Term Operating Conditions
Designed according to the continuous operation characteristics of marine power systems, the products are optimized for thermal resistance, fatigue resistance, and long-term sealing stability.
3. Complete Standardized Quality Inspection Process
Each product undergoes casting appearance inspection, precision dimensional inspection, water pressure testing, and air-tightness testing to reduce operation and maintenance risks for end users.
4. Flexible Supply Methods
Supports sample production, small-batch orders, and large-volume exports, providing long-term stable supply cooperation for spare parts distributors.
5. Customized Development and Private Brand Supporting Services
Customized development can be carried out according to customer drawings and samples, supporting requirements such as mold development and private label packaging.

VIII. Application Fields
1. Marine Power Systems
Suitable for replacement and maintenance of Daihatsu diesel engines installed on commercial ships, fishing vessels, engineering vessels, and inland waterway transport vessels.
2. Marine Auxiliary Power Equipment
Including marine diesel generator sets, auxiliary diesel engines, and ship emergency standby power systems.
3. Industrial Diesel Power Equipment
Applicable to stationary diesel generators, industrial power units, and maintenance markets for various diesel-powered equipment.

Compliance Disclaimer
This product is a third-party compatible replacement spare part independently manufactured by DONGFANG and is not an original Daihatsu Diesel product. Our company has no affiliation, authorization, or cooperation relationship with the Daihatsu Diesel brand owner. The trademarks mentioned herein belong to their respective legal rights holders and are only used to indicate the applicable engine models of the product.