Model: YC4108
Part Number: A8300-1004200
Brands: Yuchai
Engine Model: YC4108
Engine Type: Diesel
Scope of application: light and medium trucks, agricultural machinery, generator sets, marine auxiliary
The connecting rod links the piston to the crankshaft and reverses load twice per revolution. It is pulled in tension by piston inertia, pushed in compression by combustion and bent sideways as the crank swings. Part A8300-1004200 is the forged rod for the Yuchai YC4108, with a small end bush for the piston pin and bearing shells at the big end.
The YC4108 is a workhorse four-cylinder used in trucks, agricultural machinery and gensets. It often runs at high load in dusty conditions, which makes bearing condition and oil quality the deciding factors in rod life.
The rod fits YC4108 engines across its ratings. Confirm the engine plate and the old rod number before ordering. Rods from different ratings can share a length but differ in weight and small end diameter.
Rods ship with the bush fitted and new rod bolts where the design uses stretch bolts.
Rod alignment is measured with a fixture or a surface plate and pins. Bend shows as a height difference between pins, twist as an angular difference. A rod that is out by only a little still fits, but it loads the piston against the bore and wears the bearing on one side.
Shells come in standard and undersize grades and the grade must match the journal after any regrind. Check clearance with plastigauge rather than assuming. Rod bolts are stretch bolts and must be replaced every time a rod is opened.
Yuchai engines often work in dusty agricultural or construction conditions. Dust that reaches the oil accelerates bearing wear and turns a healthy rod into a failure within a season. Keep the air filter sealing properly and change oil at the severe-duty interval.
Match the part number, the engine rating and the piston pin diameter. A rod from a different rating may be the wrong weight, which shows as vibration at speed and early main bearing wear.
Rods are packed in a rigid carton with the big end protected and caps wired to their rods. If the shipment includes pistons, tell us so they can travel together.
Before the piston and rod go into the bore, confirm that the ring gaps are correct for that cylinder, the pin rotates freely in the bush and the circlips seat fully in their grooves. A circlip that is not seated will come out under load and score the bore within minutes of running.
Check that the rod number matches the journal it came from. On an engine rebuilt for the first time the numbers may not be present, so mark them yourself during disassembly. Mixing caps between rods is a reliable way to destroy a big end bearing in the first hundred hours.
Rod bolts are the most highly stressed fasteners in the engine. They are tightened to a stretch figure or to a torque plus angle, and they must be replaced every time a rod is opened. A reused bolt has already passed its elastic limit and can fail under load, which usually destroys the block as well as the rod.
Use a calibrated torque wrench and follow the specified sequence. Guessing at torque on rod bolts is the single most expensive shortcut in an engine rebuild.
New rod bolts are supplied where the design uses stretch bolts.
Yes, if the crank and other rods are undamaged. Match the weight class.
Mount on a surface plate with pins in both ends and measure with a dial gauge.
Low oil pressure, contaminated oil or detonation.
Browse the Yuchai piston and components category, and pair the rod with the YC4108 piston ring D30-1004016 or the YC4108 crankshaft B8800-1005001B.
Yuchai YC4108 Connecting Rod (1004200). This rod converts linear piston motion into rotation and carries the load through the big end shell. Weight matching and bolt condition decide how smoothly that happens.
Note the rod bolt type and length. Bolts are torque-to-yield on these engines and must be new on every rebuild, so order them with the rod.
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 gaps before the piston and rod go in. Once the sump is on, correcting either means stripping the engine again.
Ordering note. For fleet customers, a consolidated stock list can be quoted against the engine plates in service, which usually exposes duplicated part numbers across similar units.
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 |
Rods ship with the bush fitted and new rod bolts where the design uses stretch bolts.
Rod alignment is measured with a fixture or a surface plate and pins. Bend shows as a height difference between pins, twist as an angular difference. A rod that is out by only a little still fits, but it loads the piston against the bore and wears the bearing on one side.
Shells come in standard and undersize grades and the grade must match the journal after any regrind. Check clearance with plastigauge rather than assuming. Rod bolts are stretch bolts and must be replaced every time a rod is opened.
Yuchai engines often work in dusty agricultural or construction conditions. Dust that reaches the oil accelerates bearing wear and turns a healthy rod into a failure within a season. Keep the air filter sealing properly and change oil at the severe-duty interval.
Match the part number, the engine rating and the piston pin diameter. A rod from a different rating may be the wrong weight, which shows as vibration at speed and early main bearing wear.
Rods are packed in a rigid carton with the big end protected and caps wired to their rods. If the shipment includes pistons, tell us so they can travel together.
Before the piston and rod go into the bore, confirm that the ring gaps are correct for that cylinder, the pin rotates freely in the bush and the circlips seat fully in their grooves. A circlip that is not seated will come out under load and score the bore within minutes of running.
Check that the rod number matches the journal it came from. On an engine rebuilt for the first time the numbers may not be present, so mark them yourself during disassembly. Mixing caps between rods is a reliable way to destroy a big end bearing in the first hundred hours.
Rod bolts are the most highly stressed fasteners in the engine. They are tightened to a stretch figure or to a torque plus angle, and they must be replaced every time a rod is opened. A reused bolt has already passed its elastic limit and can fail under load, which usually destroys the block as well as the rod.
Use a calibrated torque wrench and follow the specified sequence. Guessing at torque on rod bolts is the single most expensive shortcut in an engine rebuild.
Browse the Yuchai piston and components category, and pair the rod with the YC4108 piston ring D30-1004016 or the YC4108 crankshaft B8800-1005001B.
New rod bolts are supplied where the design uses stretch bolts.
Yes, if the crank and other rods are undamaged. Match the weight class.
Mount on a surface plate with pins in both ends and measure with a dial gauge.
Low oil pressure, contaminated oil or detonation.
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.
