A weichai crankshaft is the main rotating part of the engine. It converts the up-and-down movement of the pistons into the rotary motion that turns the flywheel and drives the truck. Because it works under extreme load for thousands of hours, the crankshaft and its main bearings are among the most important parts to check during any engine service.
WP12 and WD615 engines power many heavy trucks, buses, and construction machines around the world. When these engines develop knocking noises or low oil pressure, the crankshaft and bearing area is usually the first place to inspect. This guide explains how these parts work, how they fail, and what to consider before you order a replacement weichai crankshaft.
Why the Crankshaft and Main Bearings Matter
The crankshaft spins inside the engine block, supported by main bearings. Each bearing carries a section of the shaft and keeps a stable oil film between the moving surfaces. The weichai main bearing shells are precision parts. If they are worn, scored, or the wrong size, the crankshaft itself can be damaged beyond repair.
This is why workshops always inspect the crankshaft journals and the bearings together. A crankshaft that looks fine at first can still be out of round or scored after high mileage. Measuring the journals with a micrometer is a normal step in any serious engine rebuild, and it tells you whether the old shaft can be reused or must be replaced. Bearing shells are cheap compared with a crankshaft, so there is no reason to take the risk of reusing them.
Signs of Crankshaft and Bearing Wear
Knocking or thumping noise
A deep knock that gets louder under load usually points to loose or worn main bearings. Do not ignore it. Continued driving can crack the crankshaft and destroy the engine block.
Low oil pressure
Worn bearings let oil escape from the clearance, so oil pressure drops even when the oil level is full. If pressure stays low after an oil and filter change, check the bearing area before ordering anything else.
Metal particles in the oil
Shiny metal flakes in the oil filter mean bearing material is breaking away. Stop the engine and inspect the sump and filter. Catching this early can save the crankshaft and the whole bottom end.
Choosing the Right Weichai Crankshaft
The first step is knowing your engine family. A wp12 crankshaft, for example, is not the same as a WD615 crankshaft. The WP12 crankshaft supplied by EPID matches the WP12 engine specification and lists part numbers such as 612630020038A and 612630020193A for easy reference.
Buyers often ask about the weichai crankshaft price. The price depends on the engine model, whether the part is original or a quality replacement, and the supplier’s shipping and warranty terms. A low price is not a bargain if the part arrives with no documentation or does not fit correctly, so compare value instead of price alone.
For a complete bottom-end service, consider related parts at the same time. The WP12 camshaft works alongside the crankshaft, and both should be checked when the timing area is open. Replacing both at once avoids a second teardown a few months later.
Main Bearings: The Partner Part
Never install a new crankshaft with old bearings. The WD615 engine bearing bush set includes the bearing shells used for a standard WD615 rebuild. A fresh weichai main bearing set protects the new crankshaft journals and restores the correct oil clearance.
When you order, tell the supplier your engine code and whether you need standard or undersize bearings. Undersize shells are sometimes used after a crankshaft has been reground, and mixing sizes is a common cause of early failure. If you are unsure, ask the workshop that measured the crankshaft to write down the journal sizes.
Buying Tips for Fleet Owners and Workshops
- Always order by engine code, not just by engine family name.
- Ask for photos and the packing list before making payment.
- Check that the part numbers match your engine specification.
- Confirm the warranty and return terms with the supplier.
If you are unsure whether you need a crankshaft or only bearings, send your engine details to the supplier. A professional seller will help you confirm the correct parts instead of pushing a larger order than you need.
Frequently Asked Questions
Can a weichai crankshaft be repaired instead of replaced?
In some cases a crankshaft can be reground and fitted with undersize bearings. The decision depends on the damage and the cost. If the shaft is cracked or heavily scored, replacement is the safer choice.
How do I confirm the right weichai crankshaft for my engine?
Check the engine code and the part number stamped on the old crankshaft, then compare them with the product listing. The WP12 crankshaft page, for example, lists the matching part numbers for that engine family.
Does a new crankshaft require new main bearings?
Yes. Always install fresh main bearings with a new crankshaft. New shells restore the correct oil clearance and protect the journals from the first start.
When you need a crankshaft, main bearings, or other rotating parts for your Weichai engine, EPID Diesel Engine Parts offers parts for the WP12, WD615, and other Weichai engines with clear part numbers and export support. Visit the Weichai engine parts page to compare products and request a quote.
