Model: WP9
Part Number: 1003321678
Brands: Weichai Power
Engine Model: WP9, WP9H, WP9G
Engine Type: Diesel
Scope of application: heavy trucks, buses, construction machinery, generator sets
Piston rings perform three jobs at once. They seal combustion gas, they conduct heat from the piston into the liner and they scrape oil back into the sump. On the Weichai WP9, set 1003321678 provides two compression rings and one oil control ring per piston, sized to the groove geometry of this nine-litre family.
Worn rings never stop an engine. They make it tired: oil consumption rises, crankcase pressure builds, the breather starts blowing vapour and performance fades as combustion gas escapes past the piston. Owners frequently blame the turbo first, which is why a compression test and a blow-by check should come before any part is ordered.
The set fits WP9, WP9H and WP9G engines in heavy trucks, buses, loaders, excavators and generator sets. Ring size matches the piston and the bore, so confirm the piston part number and whether the engine is standard or oversize before ordering. Mixing sets between variants is a common cause of oil consumption right after a rebuild.
The top ring is barrel faced and chrome plated to survive the highest temperature and pressure in the engine. The second ring is taper faced to improve oil scraping and support gas sealing. The oil control ring uses two chrome rails with an expander spring, sized for correct radial tension.
A tight gap breaks the ring when it heats; an oversized gap allows blow-by that no tuning can remove.
Oil consumption is usually the first complaint, followed by smoke at start-up and increasing crankcase pressure. On engines working at sustained load, the symptoms appear earlier because gas leakage grows with cylinder pressure.
If the bore has a ridge at the top of ring travel, replace the liner rather than fitting rings into a worn bore.
New rings cannot fix a worn piston. Measure ring groove width with the old ring and a feeler gauge; a groove that has opened lets the ring flutter, which breaks it and damages the land. Carbon packed into the groove corner also prevents seating, so clean the grooves properly rather than scraping the surface.
Check the crown for cracks around the bowl and the skirt for scuffing. A piston that has been hot may look acceptable but has lost hardness and will fail again soon after the rebuild.
New rings need cylinder pressure to seat. Gentle running glazes the bore and leaves the rings skating on a polished surface. After assembly, warm the engine and apply moderate load in cycles, varying speed rather than holding one figure. Change oil and filter after the first hours to remove metal produced while rings and bores mate.
Match the piston part number, bore size and engine rating. Standard and oversize sets look similar and cannot be interchanged. For a rebuild, order rings with liners and pistons as a matched set, which removes clearance uncertainty and shortens assembly time.
Oil that passes the rings burns in the cylinder and raises particulate emissions. In markets with emission testing this becomes a compliance matter. A failing oil ring often shows as a slight haze under load rather than visible smoke, so oil consumption records are the better early indicator.
Clean air and correct oil keep rings alive. Replace the air filter at interval, keep intake hoses sealed, use the specified oil grade and change it at the severe-duty interval. Fix overheating promptly, because heat softens ring tension and accelerates top ring wear.
One set covers one piston: two compression rings and one oil ring.
Only if the bore is within specification and still shows a proper cross hatch.
Only if the measured gap requires adjustment, using the correct specification.
Glazed bores, wrong gaps or rings fitted upside down.
Browse the Weichai piston and components category, and pair the rings with the WP9 cylinder liner 611600010011 or the WP9 cylinder head 1001677070.
Weichai WP9 Piston Ring (1003321678). These rings are the interface between piston and bore. Their radial tension and face profile decide whether the engine burns oil or blows it out of the breather.
Measure the old ring thickness and radial depth against the new set. A set that fits the groove loosely will flutter and break rather than seal.
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 WP9 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. 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: 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: WP9, WP9H, WP9G, 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 |
The top ring is barrel faced and chrome plated to survive the highest temperature and pressure in the engine. The second ring is taper faced to improve oil scraping and support gas sealing. The oil control ring uses two chrome rails with an expander spring, sized for correct radial tension.
A tight gap breaks the ring when it heats; an oversized gap allows blow-by that no tuning can remove.
Oil consumption is usually the first complaint, followed by smoke at start-up and increasing crankcase pressure. On engines working at sustained load, the symptoms appear earlier because gas leakage grows with cylinder pressure.
If the bore has a ridge at the top of ring travel, replace the liner rather than fitting rings into a worn bore.
New rings cannot fix a worn piston. Measure ring groove width with the old ring and a feeler gauge; a groove that has opened lets the ring flutter, which breaks it and damages the land. Carbon packed into the groove corner also prevents seating, so clean the grooves properly rather than scraping the surface.
Check the crown for cracks around the bowl and the skirt for scuffing. A piston that has been hot may look acceptable but has lost hardness and will fail again soon after the rebuild.
New rings need cylinder pressure to seat. Gentle running glazes the bore and leaves the rings skating on a polished surface. After assembly, warm the engine and apply moderate load in cycles, varying speed rather than holding one figure. Change oil and filter after the first hours to remove metal produced while rings and bores mate.
Match the piston part number, bore size and engine rating. Standard and oversize sets look similar and cannot be interchanged. For a rebuild, order rings with liners and pistons as a matched set, which removes clearance uncertainty and shortens assembly time.
Oil that passes the rings burns in the cylinder and raises particulate emissions. In markets with emission testing this becomes a compliance matter. A failing oil ring often shows as a slight haze under load rather than visible smoke, so oil consumption records are the better early indicator.
Clean air and correct oil keep rings alive. Replace the air filter at interval, keep intake hoses sealed, use the specified oil grade and change it at the severe-duty interval. Fix overheating promptly, because heat softens ring tension and accelerates top ring wear.
Browse the Weichai piston and components category, and pair the rings with the WP9 cylinder liner 611600010011 or the WP9 cylinder head 1001677070.
One set covers one piston: two compression rings and one oil ring.
Only if the bore is within specification and still shows a proper cross hatch.
Only if the measured gap requires adjustment, using the correct specification.
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.
