What size socket fits the crankshaft?
There isn’t a single universal socket size for the crankshaft. The correct socket is whatever matches the specific bolt you’re working on on your engine. For the typical crankshaft pulley bolt on many modern cars, 22 mm or 24 mm sockets are the most common, but there are exceptions. Always confirm with the vehicle’s service manual or by inspecting the bolt head.
Understanding what you’re working with
The term "crankshaft" refers to the main rotating shaft of the engine. When people ask about the socket size for the crankshaft, they usually mean the fastener that secures the crankshaft pulley or harmonic balancer. Other crankshaft fasteners—such as main-cap bolts or flywheel bolts—often have different head sizes or drive types (including Torx, hex, or internal Allen), and may require specialized tools.
Common sizes you might encounter
In practice, you’ll encounter a few sizes most often on crankshaft-related bolts. This list highlights the sizes you’re most likely to see across a range of makes and models.
Crankshaft pulley bolts
The pulley bolt is the most frequent target for socket sizing when servicing the crank area. The sizes you’ll commonly encounter are:
- 22 mm (7/8 inch) — widely used on many late-model cars; typically requires a 6-point or impact-rated socket.
- 24 mm (15/16 inch) — used on a number of European and Asian models; may require a deep socket.
- 19 mm (3/4 inch) or 21 mm (13/16 inch) — less common, but appear on some smaller engines or specific OEMs.
- Other variations — some engines use non-metric bolts (and in rare cases Torx or external hex), so the exact tool can differ.
Checking your owner's manual or a factory service manual is the best way to be sure, since the pulley bolt size can vary even within the same model year depending on the engine option.
How to verify the correct size for your engine
To determine the right socket size for your engine, follow these steps. The goal is to identify the bolt head size without forcing the wrong tool onto the fastener.
- Consult the service manual or parts catalog for your exact engine and model; the bolt size and tool requirement are specified there.
- Inspect the bolt head: measure across the flats with a caliper or ruler to determine the correct size in millimeters or inches.
- If you’re unsure, try the most common sizes first (22 mm and 24 mm) with a 6-point impact-rated socket, ensuring a snug fit before applying torque.
- Use the appropriate tool for the situation: a breaker bar for loosening by hand, or a pneumatic/electric impact wrench with the correct socket and proper safety precautions. Never use the wrong size socket; it can strip the bolt or damage the tool.
- When loosening, ensure the engine is secured from rotating: place the transmission in gear with the parking brake engaged or use a crankshaft locking tool if available.
Once you have verified the size, always re-check the torque spec and follow proper procedures as outlined by the manual.
Important safety and tooling notes
Working on the crank area carries significant risk: turning the engine can injure you or cause components to strike you. Always wear eye protection, ensure the vehicle is secure, and use the recommended sockets and torque tools. Use impact-rated sockets for high-torque bolts and take care around the serpentine belt and other moving parts.
Summary
There is no single universal socket size for the crankshaft. The size depends on the bolt you’re removing or installing. The most common pulley-bolt sizes are 22 mm and 24 mm (about 7/8" and 15/16"), but variations exist across makes and models. Always verify via the service manual or by measuring the bolt head, and use the correct, safety-focused tools and procedures.
