Model: YC4108
Part Number: D30-1003015A
Brands: Yuchai
Engine Model: YC4108
Engine Type: Diesel
Scope of application: light and medium trucks, agricultural machinery, generator sets, marine auxiliary
Yuchai used more than one cylinder head casting on the YC4108 across its production life. Part D30-1003015A is one of those variants, and it is not interchangeable with the other head numbers used on the same engine family because injector bore depth and port detail changed between generations. Fitting the wrong casting produces an engine that starts poorly, smokes and never quite reaches its rated output, even though every part appears to be assembled correctly.
The reliable identifiers are the casting number on the old head, the engine plate and, where possible, a photograph of the injector seat. Send all three and our team will confirm the variant before the consignment ships, which is far cheaper than returning a head from an overseas port.
Each head is cast in high-grade iron, stress relieved and machined on the deck, valve seats, guides and injector bores. The checks that decide whether it will hold are all dimensional, and we will supply the measurements on request.
Head failures on the YC4108 usually begin with cooling. A restricted radiator or a tired water pump raises metal temperature, the deck warps and the gasket loses its grip. The early symptoms are easy to misread as injector problems.
A cooling system pressure test and a combustion gas test confirm the diagnosis in minutes and save stripping a healthy head.
Worn valve guides let oil pass down the stems into the cylinders, producing blue smoke at start-up and after idling that clears once the engine is working. That pattern is often mistaken for worn rings, and the rebuild then proceeds in the wrong direction. Measuring guide clearance on the bench takes minutes and settles the question before parts are ordered.
Guides are replaceable, and a head that is otherwise sound can be reconditioned by fitting new guides and re-cutting the seats. Do this while the head is off, because leaving worn guides in place wastes the new gasket set on an engine that still smokes.
Light valve seat wear can be re-cut and a mildly warped deck machined once if enough material remains. Cracks between the seats, at the injector bore or across the deck are not economically repairable, and a repaired head that fails again usually takes the gasket and sometimes the liners with it.
Field work packs the radiator core with chaff and dust, which raises coolant temperature regardless of pump condition. Clean the core with compressed air at every major service, and check that the fan and thermostat are working. On a YC4108 in continuous field use, cooling neglect is the single most common cause of head problems.
Head bolts are torque-to-yield and must be replaced every time the head is removed. Reusing them reduces clamping force, and the gasket then leaks at high load. That failure is almost always blamed on the gasket rather than on the bolts, which is why a new bolt set should be ordered with every head.
Match the engine plate, the old casting number and the injector type. On engines that have been rebuilt before, the head may be from a later production run with a different injector seat. Photographs of the old head and the engine nameplate let our team confirm the variant with confidence rather than guesswork.
Yes, unless a bare head is requested.
No. They must be replaced every time.
A pressure test and a combustion gas test confirm it.
No. Confirm the casting number against the engine plate.
Browse the Yuchai cylinder head category, and pair the head with the YC4108 cylinder head D0300-1003000 or the YC4108 full gasket kit D30-9000100.
Yuchai YC4108 Cylinder Head (1003015). 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.
Photograph the deck, the casting number and the old gasket. Those three images usually identify the revision before anything ships, and they are far cheaper than a returned head.
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.
Fit new head bolts every time. They are torque-to-yield fasteners and reusing them reduces clamping load exactly where the gasket needs it most, under load at working temperature.
Ordering note. Lead time depends on whether the item is in stock or has to be produced; the position is confirmed before the order is accepted rather than after payment.
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 |
Head failures on the YC4108 usually begin with cooling. A restricted radiator or a tired water pump raises metal temperature, the deck warps and the gasket loses its grip. The early symptoms are easy to misread as injector problems.
A cooling system pressure test and a combustion gas test confirm the diagnosis in minutes and save stripping a healthy head.
Worn valve guides let oil pass down the stems into the cylinders, producing blue smoke at start-up and after idling that clears once the engine is working. That pattern is often mistaken for worn rings, and the rebuild then proceeds in the wrong direction. Measuring guide clearance on the bench takes minutes and settles the question before parts are ordered.
Guides are replaceable, and a head that is otherwise sound can be reconditioned by fitting new guides and re-cutting the seats. Do this while the head is off, because leaving worn guides in place wastes the new gasket set on an engine that still smokes.
Light valve seat wear can be re-cut and a mildly warped deck machined once if enough material remains. Cracks between the seats, at the injector bore or across the deck are not economically repairable, and a repaired head that fails again usually takes the gasket and sometimes the liners with it.
Field work packs the radiator core with chaff and dust, which raises coolant temperature regardless of pump condition. Clean the core with compressed air at every major service, and check that the fan and thermostat are working. On a YC4108 in continuous field use, cooling neglect is the single most common cause of head problems.
Head bolts are torque-to-yield and must be replaced every time the head is removed. Reusing them reduces clamping force, and the gasket then leaks at high load. That failure is almost always blamed on the gasket rather than on the bolts, which is why a new bolt set should be ordered with every head.
Match the engine plate, the old casting number and the injector type. On engines that have been rebuilt before, the head may be from a later production run with a different injector seat. Photographs of the old head and the engine nameplate let our team confirm the variant with confidence rather than guesswork.
Browse the Yuchai cylinder head category, and pair the head with the YC4108 cylinder head D0300-1003000 or the YC4108 full gasket kit D30-9000100.
Yes, unless a bare head is requested.
No. They must be replaced every time.
A pressure test and a combustion gas test confirm it.
No. Confirm the casting number against the engine plate.
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.
