• Zach

Dodge V10 Magnum Rocker Arm Bolt Failure

This post will cover the root cause of broken rocker arm bolts and how to repair and prevent future failures.


Cause:


The root cause of this common issue is a simple lack of maintenance not a design flaw as many forums speculate. A well maintained engine should never experience this issue. Broken rocker bolts may also come with bent pushrods and collapsed/damaged lifters. These failures are all a result of not following the manufacturer specified intervals for oil changes. As oil breaks down in an engine from heat, shear, and contamination, it forms into sludge/varnish. This sludge will eventually collect inside of the hydraulic lifters along with other locations inside the engine. When this happens the lifters can stick in a collapsed or extended state and even clog the internal oil passages. When the lifter sticks in a collapsed state the valve train will tap and engine performance will be reduced. In an extended state there is high chance of bending a pushrod or breaking the rocker bolt. This happens as there is too much lift for the valve spring and it bottoms out. When the lifters clog they do not allow oil to pass up the pushrod to oil the rocker pivot. This causes the respective rocker and pivot saddle to run dry or with very little oil. Eventually the oil film breaks down and the rocker runs metal to metal quickly wearing the surfaces. Once the wear gets bad enough the rocker will start to bind on the pivot and the bolt will bend until it fails in bending fatigue. Below are some examples of valvetrain damage from sludge.




Repair:


Please refer to the Factory Service Manual (FSM) for full instructions.

To repair a broken rocker bolt the upper/lower intake manifold valve covers must be removed from the engine. This process is detailed in the FSM. Once you have access to the rocker arms remove them and inspect for wear as pictured below.

If wear is present on the rockers and lifters they should either be replaced or repaired. The pivots are discontinued from Dodge so used parts are currently the only source. Aftermarket roller rockers are also available from Crower. Detailed instructions on repairing the rocker arms and pivots can be found here. Replace any damaged pushrods.


To remove the lifters from the engine block the head gasket must be trimmed back to the head to allow room for the lifters to be pulled out. Lifters should either be replaced or cleaned depending on time and budget. Detailed instructions on cleaning lifter can be found here.


Reassembly should follow the process in the FSM. Failure to replace or repair the rockers and lifters will likely result in future valvetrain failure.

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