3890955 389-0955 CYLINDER HEAD For C6.4 Engine

1. Surface Condition: High-quality cylinder heads have cast/machined surfaces free of sand holes, air holes, and cracks. The sealing surface (the plane that mates with the cylinder block) is smooth and free of scratches, dents, or rust, and feels smooth to the touch.

2. Marking Clarity: Brand logos, part numbers, production batches, and other information must be laser-engraved or stamped, clear and resistant to wear; inferior parts often lack markings or have blurry markings, or even contain typos.

3. Detailed Craftsmanship: Valve seats and guide hole edges are free of burrs; welds (if any) are free of incomplete welds and cracks; cooling water and oil passage interfaces are free of casting residue, and internal passages are unobstructed.

1. Material Verification: Suppliers are required to provide material certificates. Cast iron cylinder heads must have a carbon content of 3.0%-3.5% (high temperature resistance, impact resistance), and aluminum alloy cylinder heads must be made of engineering-grade materials such as ADC12 (lightweight, good heat dissipation). Parts without material reports will be rejected.

2. Dimensional Accuracy: The flatness of the sealing surfaces must be measured using a ruler and feeler gauge (cast iron ≤ 0.15mm, aluminum alloy ≤ 0.1mm). Exceeding these tolerances will lead to seal failure. Bolt hole spacing must be uniform, with no stripped threads on the inner wall. Standard bolts should be able to be tightened smoothly without jamming.

3. Key Structures: The machined edges of valve spring seats and fuel injector mounting holes must be neat and free from deformation. The cooling water channels must be free of sand core residue; when viewed against the light, the inner wall should be smooth, without obvious impurities or casting defects.

1. Airtightness Test: Using specialized equipment, pressurize the cooling water and oil passages with air and observe the pressure stability. No leakage indicates good internal sealing, preventing water and oil leaks during use.

2. Hardness Test: Measure the cylinder head surface with a hardness tester. Cast iron cylinder heads should have a hardness between HB200-HB240, and aluminum alloy cylinder heads between HB85-HB105. Insufficient hardness can lead to deformation and wear.

3. Disassembly Comparison (Used Parts Reference): If an original used cylinder head is available, compare the weight (the weight error between high-quality parts and the original factory parts should be ≤3%) and key dimensions (such as valve bore diameter and sealing surface width). Significant differences raise concerns about quality.

1. The surface has obvious sand holes or cracks, or the sealing surface is warped or severely scratched;

2. The markings are blurry, the part number is easily erased, and there are no certificates of conformity, material certificates, or any other proof;

3. The bolt holes are stripped, the water passages are blocked, or the fit with the cylinder block and cylinder head gasket is not tight during trial assembly.