Pushrods must be removed from the vehicle before they can be inspected.
During inspection, some pushrods may be found to have a groove worn in the area in which they pass through the cylinder head, and some may have tip wear. Also, the ends of the pushrods should be checked for nicks, grooves, roughness, or signs of excessive wear. Bent pushrods can be the result of valve timing, valve sticking, or improper valve adjustment.
Bent or broken pushrods indicate interference in the valve train. Common causes are the use of incorrect valve springs or an installed height less than specified, which can cause coil bind. Also, insufficient valve-to-piston clearance can cause a collision between the valve and piston at high engine speeds.
Visually inspect the two tip surfaces for wear. Normal wear results in a smooth and polished finish. Wear on the side of the pushrod indicates the pushrod guide is defective and it too must be replaced.
The pushrods can be visually checked for straightness while they are installed in the engine by rotating them with the valve closed. With the pushrods out of the engine, they can be checked for straightness by rolling them over a flat surface such as a surface plate. Total pushrod run-out should be less than 0.003 in. (0.08 mm). If a pushrod is not straight, it will appear to hop as it is rolled.
Clean the oil passage with a piece of wire and solvent. The oil passage should be circular and have a well-defined edge. If the hole is oval shaped or the edge is chamfered, replace the pushrod.