Model: YC4108
Part Number: D30-1004016
Brands: Yuchai
Engine Model: YC4108
Engine Type: Diesel
Scope of application: light and medium trucks, agricultural machinery, generator sets, marine auxiliary
The Yuchai YC4108 is a four-cylinder diesel used widely in light and medium trucks, agricultural equipment and generator sets across Southeast Asia, Africa and Latin America. Part D30-1004016 is the piston ring set for this engine, with two compression rings and one oil control ring per piston.
Rings seal combustion gas, conduct heat from the piston into the liner and scrape oil back to the sump. When they wear, the engine does not stop; it becomes weak and smoky, and oil consumption rises steadily until a rebuild is the only option.
The set fits YC4108 engines in trucks, agricultural machinery and gensets. Confirm the piston part number and whether the engine is standard or oversize before ordering. Yuchai built the 4108 in several ratings, and ring thickness differs between some variants.
A tight gap breaks the ring when it heats; an oversized gap allows blow-by that no tuning can remove.
Measure in the liner the ring will run in, with the ring pushed square to a depth near the bottom of ring travel. Measuring in a different bore, or with the ring tilted, gives a reading that is wrong by enough to cause a failure.
New rings cannot fix a worn piston. Measure groove width with the old ring; an opened groove lets the ring flutter and break. Clean carbon from the groove corner properly rather than scraping the surface.
Many YC4108 engines work in dusty agricultural or construction conditions with modest filtration. Dust ingress wears rings and liners faster than any other cause, so the air filter and intake hoses deserve as much attention as the oil. An engine that has run with a leaking intake will need rings at half the expected hours.
Run at varying load after the rebuild, increasing gradually, and change oil early. A high-detergent oil can slow bedding-in, so follow the workshop recommendation for the break-in period rather than the normal service oil.
Clean air and correct oil keep rings alive. Replace the air filter at interval, keep intake hoses sealed and use the specified oil grade at the severe-duty interval. Fix overheating promptly, because heat softens ring tension.
Yuchai 4108 engines that have been rebuilt before may have oversize bores, and the ring set must match. Measure the bore at three heights and two directions before ordering. A standard set fitted to an oversize bore will have excessive end gaps and will not control blow-by, no matter how carefully it is assembled.
If the bore is already at the maximum oversize, the liner must be replaced rather than re-honed. Honing further removes material without restoring roundness, and the engine will be back out of service within a season.
Many YC4108 engines reach the point where oil consumption is the main complaint rather than power loss. The oil ring usually loses tension first, while the compression rings still look serviceable. Replacing only the compression rings leaves the oil consumption unchanged and is a common wasted repair.
Always replace the full set per piston, and check the piston oil drain holes for blockage. A blocked drain returns oil to the combustion chamber no matter how good the ring is.
One set covers one piston: two compression rings and one oil ring.
No. Confirm the engine model and piston number before ordering.
Only if the bore is within specification and shows a proper cross hatch.
Glazed bores, wrong gaps or rings fitted upside down.
Browse the Yuchai piston and components category, and pair the rings with the YC4108 connecting rod A8300-1004200 or the YC4108 piston B8800-1004001.
Yuchai YC4108 Piston Ring (1004016). Compression sealing and oil control both depend on this set. The top ring takes the highest temperature, the second supports sealing, and the oil ring returns oil to the sump.
Confirm the ring set matches the piston groove width and the rating. Rings are specified per engine rating, not by bore diameter alone.
Numbers beginning 1004 are numeric-series numbers used on later WP7 and WP8 production, where mounting detail changed without a change of nominal type. On this engine, confirm the YC4108 application against the engine plate before ordering.
Stagger the end gaps around the piston and oil the rings before fitting. Forcing a ring over the piston without a compressor can crack it invisibly.
Ordering note. Warranty is twelve months against manufacturing defects. Failures caused by incorrect clearance, overheating or debris are assessed on the returned part rather than refused outright.
Related reading: Piston Ring Selection: Gap, Tension and Bore Condition
| 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 |
A tight gap breaks the ring when it heats; an oversized gap allows blow-by that no tuning can remove.
Measure in the liner the ring will run in, with the ring pushed square to a depth near the bottom of ring travel. Measuring in a different bore, or with the ring tilted, gives a reading that is wrong by enough to cause a failure.
New rings cannot fix a worn piston. Measure groove width with the old ring; an opened groove lets the ring flutter and break. Clean carbon from the groove corner properly rather than scraping the surface.
Many YC4108 engines work in dusty agricultural or construction conditions with modest filtration. Dust ingress wears rings and liners faster than any other cause, so the air filter and intake hoses deserve as much attention as the oil. An engine that has run with a leaking intake will need rings at half the expected hours.
Run at varying load after the rebuild, increasing gradually, and change oil early. A high-detergent oil can slow bedding-in, so follow the workshop recommendation for the break-in period rather than the normal service oil.
Clean air and correct oil keep rings alive. Replace the air filter at interval, keep intake hoses sealed and use the specified oil grade at the severe-duty interval. Fix overheating promptly, because heat softens ring tension.
Yuchai 4108 engines that have been rebuilt before may have oversize bores, and the ring set must match. Measure the bore at three heights and two directions before ordering. A standard set fitted to an oversize bore will have excessive end gaps and will not control blow-by, no matter how carefully it is assembled.
If the bore is already at the maximum oversize, the liner must be replaced rather than re-honed. Honing further removes material without restoring roundness, and the engine will be back out of service within a season.
Many YC4108 engines reach the point where oil consumption is the main complaint rather than power loss. The oil ring usually loses tension first, while the compression rings still look serviceable. Replacing only the compression rings leaves the oil consumption unchanged and is a common wasted repair.
Always replace the full set per piston, and check the piston oil drain holes for blockage. A blocked drain returns oil to the combustion chamber no matter how good the ring is.
Browse the Yuchai piston and components category, and pair the rings with the YC4108 connecting rod A8300-1004200 or the YC4108 piston B8800-1004001.
One set covers one piston: two compression rings and one oil ring.
No. Confirm the engine model and piston number before ordering.
Only if the bore is within specification and shows a proper cross hatch.
Glazed bores, wrong gaps or rings fitted upside down.
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.
