Model: YC4108
Part Number: A8600-1004001
Brands: Yuchai
Engine Model: YC4108
Engine Type: Diesel
Scope of application: light and medium trucks, agricultural machinery, generator sets, marine auxiliary
The Yuchai YC4108 has been built in several variants over a long production life, and the pistons differ between them in bowl shape and compression height. Part A8600-1004001 is one of those piston numbers, and matching it to the engine is more important than matching the bore diameter alone, because two pistons of the same diameter can produce very different combustion.
The reliable identifiers are the engine plate, the old piston number stamped on the crown and a photograph of the bowl. When a piston is ordered without those checks, the engine often runs but smokes, and the cause is rarely traced back to the piston because everything fits.
A diesel piston absorbs combustion pressure at the crown, transfers heat through the rings and liner, and must keep its ring grooves in shape while doing it. In a YC4108 working in a field or on a construction site, that load arrives continuously for hours, so crown temperature stays high and the cooling path matters more than any transient behaviour.
The details that decide durability are invisible once assembled: bowl shape, groove width, pin bore clearance and skirt profile. Each affects sealing, noise or oil consumption, and none of them can be corrected later without opening the engine again.
Pistons are produced to the original drawing and inspected at the points that control how long they last. The checks are straightforward but they are the difference between a piston that runs for years and one that smokes within months.
Every failed piston carries evidence of its cause, and reading that evidence before ordering parts is what prevents a repeat failure. A melted crown edge usually means over-fuelling or late injection. A cracked crown centre points to overheating. Scuffing on one side indicates a bent rod or a misaligned bore.
Assembly is simple if the measurements are done first. The most common error is fitting a piston without checking ring gaps in the actual bore, which produces blow-by that looks like a machining fault later.
Agricultural YC4108 engines work in conditions that punish filtration. Dust that reaches the cylinder acts as an abrasive between the rings and the bore, wearing both quickly and depositing grit in the oil. The air filter housing, its seals and the intake hoses deserve as much attention as the oil on these engines.
Two pistons with the same bore can differ in compression height and bowl shape, and both will physically fit. The wrong one changes the compression ratio and the combustion pattern, producing smoke, high exhaust temperature and poor fuel economy. No injector adjustment can correct combustion chamber geometry.
New pistons and rings need load to seat. Avoid long idling, vary engine speed and apply moderate load during the first hours, then change oil and filter. A gentle break-in that never loads the engine is as harmful as abuse, because the bores glaze and the rings never seal.
Correct injection timing, clean fuel and adequate cooling keep pistons alive. Replace fuel filters at interval and fix overheating promptly, because crown temperature rises quickly when coolant flow drops and a piston that has been hot is permanently weakened.
It is supplied bare by default. Complete assemblies are available on request.
Yes, within one engine.
Yes, if the liner and the rest of the set are undamaged.
Over-fuelling, incorrect timing or blocked cooling.
Browse the Yuchai piston and components category, and pair the piston with the YC4108 piston B8800-1004001 or the YC4108 piston ring D30-1004016.
Yuchai YC4108 Piston (1004001). Heat and pressure both arrive at this component first. The ring grooves control oil and compression, and the bowl decides how efficiently the fuel burns.
Check the ring groove width with the old ring and a feeler gauge. An opened groove lets the new ring flutter, and a fluttering ring breaks.
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.
Check piston-to-bore clearance and ring end gaps in the actual bore. Measuring in a spare liner gives a false reading and is a common cause of oil use after a rebuild.
Ordering note. Photographs of the actual unit can be sent before dispatch on request. That is the cheapest way to avoid a return when a casting revision is in doubt.
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 |
Pistons are produced to the original drawing and inspected at the points that control how long they last. The checks are straightforward but they are the difference between a piston that runs for years and one that smokes within months.
Every failed piston carries evidence of its cause, and reading that evidence before ordering parts is what prevents a repeat failure. A melted crown edge usually means over-fuelling or late injection. A cracked crown centre points to overheating. Scuffing on one side indicates a bent rod or a misaligned bore.
Assembly is simple if the measurements are done first. The most common error is fitting a piston without checking ring gaps in the actual bore, which produces blow-by that looks like a machining fault later.
Agricultural YC4108 engines work in conditions that punish filtration. Dust that reaches the cylinder acts as an abrasive between the rings and the bore, wearing both quickly and depositing grit in the oil. The air filter housing, its seals and the intake hoses deserve as much attention as the oil on these engines.
Two pistons with the same bore can differ in compression height and bowl shape, and both will physically fit. The wrong one changes the compression ratio and the combustion pattern, producing smoke, high exhaust temperature and poor fuel economy. No injector adjustment can correct combustion chamber geometry.
New pistons and rings need load to seat. Avoid long idling, vary engine speed and apply moderate load during the first hours, then change oil and filter. A gentle break-in that never loads the engine is as harmful as abuse, because the bores glaze and the rings never seal.
Correct injection timing, clean fuel and adequate cooling keep pistons alive. Replace fuel filters at interval and fix overheating promptly, because crown temperature rises quickly when coolant flow drops and a piston that has been hot is permanently weakened.
Browse the Yuchai piston and components category, and pair the piston with the YC4108 piston B8800-1004001 or the YC4108 piston ring D30-1004016.
It is supplied bare by default. Complete assemblies are available on request.
Yes, within one engine.
Yes, if the liner and the rest of the set are undamaged.
Over-fuelling, incorrect timing or blocked cooling.
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.
