Pushrod

A pushrod is a long, slender steel tube used in overhead valve (OHV) engines, also known as pushrod engines. While modern overhead cam (OHC) engines mount the camshaft directly in the cylinder head above the valves, OHV engines place the camshaft down inside the engine block. The pushrod is the mechanical link that bridges this distance.

Inside the engine, as the camshaft rotates, its lobes lift the valve lifters. The lifter pushes up on the bottom of the pushrod, which travels up through channels in the engine block and cylinder head. The top of the pushrod pushes against the rocker arm, which pivots to push the engine valve open. Most pushrods are hollow, allowing pressurized engine oil to travel up through their center to lubricate the rocker arms and valve stems.

Pushrods are highly durable but can bend or wear under extreme conditions. If the engine is over-revved, or if a valve sticks open and collides with a piston, the pushrod will bend to absorb the impact, protecting other engine components. A bent pushrod causes a loud clicking or ticking noise from the valvetrain, engine misfires, and a loss of power.

Replacing a bent pushrod involves removing the valve cover and rocker arms. It is a straightforward repair, but diagnosing the root cause (such as a stuck valve or over-revving) is critical to prevent the new pushrod from bending immediately.