Model: WP7 / WP8 / WP9
Part Number: 1004961918
Brands: Weichai Power
Engine Model: WP7, WP8, WP9, WP7H, WP8H
Engine Type: Diesel
Scope of application: trucks, buses, construction machinery, generator sets
A diesel piston absorbs heat from combustion, transfers most of it to the rings and liner, and must keep the ring grooves in shape while doing so. On the Weichai WP7, WP8 and WP9 family, part 1004961918 is the piston used across these ratings, with a cooling gallery through which oil is sprayed to control crown temperature.
Piston design details matter more than they look. The crown bowl shape controls how the fuel burns, the ring groove lands control how long the rings seal, and the pin bore controls noise. A piston that is close but not correct will run, and then fail quietly through oil consumption or a cracked crown.
The piston fits WP7, WP7H, WP8, WP8H and WP9 engines in trucks, buses, loaders and generator sets. Confirm the engine plate and the old piston number: compression ratio and bowl shape changed between some ratings, and the correct piston must match the injector and the ECU calibration.
Pistons ship with protective wrapping and, where applicable, the pin and circlips. Tell us if you need the complete assembly with rings fitted.
When one piston is damaged, find the cause before replacing it. An over-fuelling injector or a blocked cooling jet will destroy the new piston in the same way.
Match the part number, the engine rating and the piston bowl shape. The same bore can carry pistons with different bowls for different emissions levels. Send us the old piston crown photo and the engine plate and we will confirm before shipping.
Correct injection timing, clean fuel and adequate cooling are what keep pistons alive. Replace fuel filters at interval, keep the cooling jets clear and never run the engine with a failed turbo that is passing oil into the intake. Fix overheating promptly, because piston crown temperature rises quickly when coolant flow drops.
Diesel pistons are cooled from below by oil jets aimed at the underside of the crown. If a jet is blocked or missing, the crown overheats and can crack or melt at the bowl edge, even when the rest of the engine is healthy. Before fitting new pistons, check every jet for flow and confirm the correct nozzle is fitted, because some rebuilds end with the wrong jet installed.
Piston pin fit also matters. A floating pin in a worn bore makes a hollow knock at idle that fades with speed. Check the pin bore diameter and the small end bush together. If the pin rocks visibly in the piston, the piston is worn and replacement is the only reliable repair.
Every failed piston tells you something about the engine. A melted crown edge points to over-fuelling or late injection. A cracked crown centre points to overheating or a blocked cooling jet. Scuffed skirts on one side indicate a bent rod or a misaligned bore. Scoring around the whole skirt points to oil starvation or overheating of the piston itself.
Read the evidence before ordering parts. Replacing a piston without fixing the cause produces the same failure again within a few thousand kilometres, and repeat failures are far more expensive than a careful diagnosis the first time.
It is supplied bare by default. Complete assemblies with rings fitted are available on request.
Yes. Pistons in one engine should be from the same weight class to keep the crank balanced.
Yes, if the liner and the rest of the set are undamaged. Check ring gaps in the actual bore.
Usually over-fuelling, incorrect injection timing or a blocked cooling jet. Diagnose before rebuilding.
Browse the Weichai piston and components category, and pair the piston with the WP7 and WP8 cylinder liner 610800010503 or the WP7 and WP8 connecting rod 610800030073.
We offer OEM quality and excellent after-sales service as a complementary option. Engine brands supported include Weichai, Baudouin, Yuchai, Caterpillar, FAW Xichai, Sinotruk, Cummins and other engine parts. Specifically engine overhaul kits, pistons, cylinder liners, crankshafts, camshafts, fuel pumps, water pumps, lube pumps, injectors, and other performance parts.
If you are not sure about the part number that you need, please provide all the information you have, such as the equipment nameplate, engine nameplate or engine number, or real photos.
A diesel piston absorbs heat from combustion, transfers most of it to the rings and liner, and must keep the ring grooves in shape while doing so. On the Weichai WP7, WP8 and WP9 family, part 1004961918 is the piston used across these ratings, with a cooling gallery through which oil is sprayed to control crown temperature.
Piston design details matter more than they look. The crown bowl shape controls how the fuel burns, the ring groove lands control how long the rings seal, and the pin bore controls noise. A piston that is close but not correct will run, and then fail quietly through oil consumption or a cracked crown.
The piston fits WP7, WP7H, WP8, WP8H and WP9 engines in trucks, buses, loaders and generator sets. Confirm the engine plate and the old piston number: compression ratio and bowl shape changed between some ratings, and the correct piston must match the injector and the ECU calibration.
| We Are 30 Years Diesel Engine Parts Supplier | |
| Brand | EPID |
| Warranty | 12 Months |
| Condition | 100%New |
| More Models | Weichai: WP7, WP8, WP9, WP7H, WP8H, 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 ship with protective wrapping and, where applicable, the pin and circlips. Tell us if you need the complete assembly with rings fitted.
When one piston is damaged, find the cause before replacing it. An over-fuelling injector or a blocked cooling jet will destroy the new piston in the same way.
Match the part number, the engine rating and the piston bowl shape. The same bore can carry pistons with different bowls for different emissions levels. Send us the old piston crown photo and the engine plate and we will confirm before shipping.
Correct injection timing, clean fuel and adequate cooling are what keep pistons alive. Replace fuel filters at interval, keep the cooling jets clear and never run the engine with a failed turbo that is passing oil into the intake. Fix overheating promptly, because piston crown temperature rises quickly when coolant flow drops.
Diesel pistons are cooled from below by oil jets aimed at the underside of the crown. If a jet is blocked or missing, the crown overheats and can crack or melt at the bowl edge, even when the rest of the engine is healthy. Before fitting new pistons, check every jet for flow and confirm the correct nozzle is fitted, because some rebuilds end with the wrong jet installed.
Piston pin fit also matters. A floating pin in a worn bore makes a hollow knock at idle that fades with speed. Check the pin bore diameter and the small end bush together. If the pin rocks visibly in the piston, the piston is worn and replacement is the only reliable repair.
Every failed piston tells you something about the engine. A melted crown edge points to over-fuelling or late injection. A cracked crown centre points to overheating or a blocked cooling jet. Scuffed skirts on one side indicate a bent rod or a misaligned bore. Scoring around the whole skirt points to oil starvation or overheating of the piston itself.
Read the evidence before ordering parts. Replacing a piston without fixing the cause produces the same failure again within a few thousand kilometres, and repeat failures are far more expensive than a careful diagnosis the first time.
Browse the Weichai piston and components category, and pair the piston with the WP7 and WP8 cylinder liner 610800010503 or the WP7 and WP8 connecting rod 610800030073.
It is supplied bare by default. Complete assemblies with rings fitted are available on request.
Yes. Pistons in one engine should be from the same weight class to keep the crank balanced.
Yes, if the liner and the rest of the set are undamaged. Check ring gaps in the actual bore.
Usually over-fuelling, incorrect injection timing or a blocked cooling jet. Diagnose before rebuilding.
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.
