Model: YC4108
Part Number: D0300-1003000
Brands: Yuchai
Engine Model: YC4108
Engine Type: Diesel
Scope of application: light and medium trucks, agricultural machinery, generator sets, marine auxiliary
The cylinder head closes the combustion chamber, carries the valve train and routes coolant around the injector and valve bridges. Part D0300-1003000 is one of the heads used on the Yuchai YC4108, and it is the part where heat and pressure meet.
When a head warps or cracks, coolant enters the cylinder or compression enters the water jacket. The symptoms are easy to misread: white smoke, coolant loss with no external leak and overheating under load are all typical.
Yuchai used more than one head casting on the 4108 across production periods. Injector bore depth and port detail differ, so confirm the engine plate and the old casting number before ordering. A head from the wrong generation fits but changes combustion and produces hard starting.
Worn guides let oil down the stems and produce blue smoke at start-up that clears once the engine works. That pattern is often mistaken for worn rings, and the rebuild goes in the wrong direction. Measuring guide clearance on the bench settles the question in minutes.
Light seat wear can be re-cut and a mildly warped deck machined once. Cracks between seats, at the injector bore or across the deck are not economically repairable, and a repaired head that fails again usually takes the gasket with it.
Keep coolant at the correct concentration, clean the radiator core in dusty conditions and replace the thermostat on schedule. On agricultural engines the core is often packed with chaff, which raises temperature without any component fault.
Head bolts are torque-to-yield and must be replaced every time. Reusing them reduces clamping force and produces a leak at high load that looks like a gasket failure.
Match the engine plate, the old casting number and the injector type. Send photographs of the old head and the engine nameplate and we will confirm the variant before shipping.
A worn or pitted injector seat lets compression escape past the copper washer. The symptom is a chuffing noise at the injector and a misfire that is hard to trace, and it is often mistaken for an injector fault. Check the seat while the head is on the bench and re-cut it if necessary, because doing it later means removing the head again.
Yuchai used more than one head casting on the 4108 across production periods, and injector bore depth and port detail differ between them. A head from the wrong generation bolts up but changes combustion, producing hard starting and smoke that no injector adjustment can fix.
Keep coolant at the correct concentration, clean the radiator core in dusty conditions and replace the thermostat on schedule. On agricultural engines the core is often packed with chaff, which raises coolant temperature without any component fault. A head that runs hot will warp regardless of how well it was machined.
A gasket only seals a surface that is flat. Measure the block deck and the head face with a straight edge and feeler gauge along the length and both diagonals. A deck that is out by more than the service limit must be machined, and no gasket compensates for it. Record the measurement so the next overhaul has a reference.
Keep the head on its side or on a wooden pallet, never resting on the deck face, because a small nick on the deck becomes a compression leak. Cover the injector bores and the valve seats to keep dust and swarf out, and oil the machined faces lightly if the head will wait more than a few days.
Yes, unless a bare head is requested.
No. They must be replaced.
Pressure test and combustion gas test.
No. Confirm the casting number.
Browse the Yuchai cylinder head category, and pair the head with the YC4108 full gasket kit D30-9000100 or the YC4108 camshaft D30-1006000A.
Yuchai YC4108 Cylinder Head (1003000). The head carries combustion pressure, the valve train and the injectors, and it has to seal all three against a block that expands at a different rate. It is the most highly stressed casting in the engine.
Confirm the injector bore depth matches the injectors in use. Shimming an injector to compensate for a different bore is a common shortcut that produces smoke and hard starting.
Numbers beginning 1003 belong to the numeric series used across WP7, WP8 and WP9. The engine plate is the fastest way to confirm which revision applies. On this engine, confirm the YC4108 application against the engine plate before ordering.
Have the head checked for flatness and, where necessary, pressure tested before assembly. A crack that does not leak cold will open once the engine reaches temperature.
Ordering note. Mixed pallets are accepted, so a single order can carry the block, the gasket set and the small seals together instead of arriving in three shipments.
Related reading: Cylinder Head Rebuild: Valves, Guides and Seats
| We Are 30 Years Diesel Engine Parts Supplier | |
| Brand | EPID |
| Warranty | 12 Months |
| Condition | 100%New |
| More Models | Weichai: YC4108, and other Weichai series. |
| Shipping | By sea / air / express (DHL, FEDEX, TNT, UPS, EMS) |
| Packing | Standard exporting packing or as required |
| Payment Term | L/C, T/T, Western Union, Trade Assurance |
| Delivery Time | 3-7 days (depend on order) |
| Selling Point | 1. On-time Delivery 2. Genuine Quality Assurance 3. Professional Supplier |
Worn guides let oil down the stems and produce blue smoke at start-up that clears once the engine works. That pattern is often mistaken for worn rings, and the rebuild goes in the wrong direction. Measuring guide clearance on the bench settles the question in minutes.
Light seat wear can be re-cut and a mildly warped deck machined once. Cracks between seats, at the injector bore or across the deck are not economically repairable, and a repaired head that fails again usually takes the gasket with it.
Keep coolant at the correct concentration, clean the radiator core in dusty conditions and replace the thermostat on schedule. On agricultural engines the core is often packed with chaff, which raises temperature without any component fault.
Head bolts are torque-to-yield and must be replaced every time. Reusing them reduces clamping force and produces a leak at high load that looks like a gasket failure.
Match the engine plate, the old casting number and the injector type. Send photographs of the old head and the engine nameplate and we will confirm the variant before shipping.
A worn or pitted injector seat lets compression escape past the copper washer. The symptom is a chuffing noise at the injector and a misfire that is hard to trace, and it is often mistaken for an injector fault. Check the seat while the head is on the bench and re-cut it if necessary, because doing it later means removing the head again.
Yuchai used more than one head casting on the 4108 across production periods, and injector bore depth and port detail differ between them. A head from the wrong generation bolts up but changes combustion, producing hard starting and smoke that no injector adjustment can fix.
Keep coolant at the correct concentration, clean the radiator core in dusty conditions and replace the thermostat on schedule. On agricultural engines the core is often packed with chaff, which raises coolant temperature without any component fault. A head that runs hot will warp regardless of how well it was machined.
A gasket only seals a surface that is flat. Measure the block deck and the head face with a straight edge and feeler gauge along the length and both diagonals. A deck that is out by more than the service limit must be machined, and no gasket compensates for it. Record the measurement so the next overhaul has a reference.
Keep the head on its side or on a wooden pallet, never resting on the deck face, because a small nick on the deck becomes a compression leak. Cover the injector bores and the valve seats to keep dust and swarf out, and oil the machined faces lightly if the head will wait more than a few days.
Browse the Yuchai cylinder head category, and pair the head with the YC4108 full gasket kit D30-9000100 or the YC4108 camshaft D30-1006000A.
Yes, unless a bare head is requested.
No. They must be replaced.
Pressure test and combustion gas test.
No. Confirm the casting number.
EPID supplies diesel engine parts for Weichai, Baudouin, Yuchai, Caterpillar, Sinotruk, FAW Xichai and Cummins engines. Every order is checked against the original part number before packing, and our team can identify a part from a photo of the engine plate. Ask for a quotation with your model and quantity and we will reply within one working day.
