What Causes a Bent Pushrod

A bent pushrod in an internal combustion engine is typically a result of mechanical stress or a failure in the engine’s valve train system. Pushrods are components that transfer the motion from the camshaft to the valves, allowing them to open and close at the right times in the engine’s combustion cycle.

When a pushrod becomes bent, it can lead to poor engine performance and potentially severe engine damage if not addressed promptly.

Here are some common causes of bent pushrods:

1. Valve-to-piston contact:

The most common cause of bent pushrods is when a valve comes into contact with the piston during the engine’s operation. This usually happens due to a timing issue, such as incorrect camshaft timing or a malfunctioning timing belt or chain.

When the valve timing is off, the valves can open or close at the wrong time, leading to interference with the pistons. This can result in a bent pushrod, damaged valves, and even piston damage.

2. Over-revving the engine:

Running the engine at excessively high RPMs (revolutions per minute) can cause the valves to float, which means they don’t fully seat or close during their cycle. This can lead to the pushrods bending due to the high-speed contact between the valves and pistons.

3. Mechanical failure:

Pushrods can also bend due to material fatigue or other mechanical issues within the engine. This can include manufacturing defects, wear and tear over time, or issues with the pushrod’s design or material quality.

4. Incorrect pushrod length:

Installing pushrods that are too long or too short for the engine’s configuration can cause them to bind or experience excessive stress, potentially leading to bending.

5. High-performance modifications:

When modifying an engine for higher performance, such as installing a more aggressive camshaft or using aftermarket components, it’s crucial to ensure that all the components in the valve train system are compatible. Incompatibilities or incorrect installation can result in bent pushrods.

6. Hydraulic lifter malfunction:

In engines equipped with hydraulic lifters, a malfunction in the lifter can lead to excessive valve lash or lash adjuster failure. This can cause the pushrod to experience abnormal stress and potentially bend.

7. Valve spring issues:

Weak or broken valve springs can lead to valve float, which can result in bent pushrods when the valves open and close too rapidly.

To prevent bent pushrods, it’s essential to maintain the engine according to the manufacturer’s recommendations, ensure proper installation of components during repairs or modifications, and regularly inspect and adjust valve timing and clearances. If you suspect bent pushrods in your engine, it’s advisable to consult a qualified mechanic to diagnose and address the underlying issue promptly.


Credit: mechanics.stackexchange.com

Bent Pushrods In A Lawn Mower Engine! What Causes Them?


The bent pushrod is a common issue faced by engine owners, and several factors can lead to it. In this blog post, we have covered several reasons that can cause this malfunction in an engine. The most common culprits can be traced back to oil starvation, severe camshaft wear, and improper valve adjustment.

However, the damage caused by a bent pushrod can wreck an engine and put a hole in the wallet. Therefore, it’s essential to keep a regular check on the engine’s oil levels, ensure a functioning valve system, and have the timing belt checked frequently.

Preventive maintenance is crucial, and being mindful of the right engine function can save you a lot of time, money, and stress in the long run. So, don’t overlook the signs of a bent pushrod and take the necessary steps to maintain the excellent health of your engine.