Ford Mustang Buzzing Type Noise From Upper Engine Area

Some Ford Mustang owners have reported an irritating buzzing type noise coming from the upper engine area during moderate acceleration. This article explores the source of this noise and outlines the diagnostic and repair procedures.

Problem Explanation

The Ford Mustang can develop an annoying buzzing type noise from the upper engine area near the intake manifold at engine speeds between 1500-2500 rpm. This noise is most noticeable when the engine is under load, such as when accelerating or driving uphill.

The source of this noise has been traced to a failure of the synchronizer shaft upper bushing. The synchronizer shaft connects the transmission to the engine and allows smooth shifting between gears. The upper bushing provides stability and minimizes vibration. When this bushing wears out, it allows excessive movement of the shaft which creates vibration against the aluminum intake manifold, resulting in a resonant buzzing noise.

Diagnostic Procedures 

Diagnosing this issue requires basic hand tools and a trained technician. The major steps are:

• Test drive the vehicle and pinpoint when the noise occurs based on engine rpm. Attempt to replicate it repeatedly.
• Visually inspect engine accessories drives and belts for abnormalities indicating worn bearings or pulleys.  
• Use a stethoscope or long screwdriver as an improvised listening tool on the intake manifold area to isolate the noise origin.
• Remove air intake assembly for access to synchronizer shaft bushing. Check for excessive play in shaft by moving it by hand.
• If movement is greater than 3mm, the upper bushing has likely failed. Further disassembly and inspection will confirm.

Repair Solutions

Replacing the failed synchronizer shaft upper bushing will resolve the buzzing noise in most cases.

Additional steps involve:

• Inspect shaft itself for damage which may warrant replacement.
• Install new bushing and reassemble components.
• Road test to confirm noise has been eliminated through all engine rpms.

If noise returns, the lower bushing may also need replacement.

Ford Mustang Model Years Potentially Impacted

This issue has been reported in Ford Mustangs from 2010-2014 models equipped with the 4.6L V8 engine and 6R80 6-speed automatic transmission.

Vehicle Components Potentially Affected

The major components requiring inspection or replacement are:

• Synchronizer shaft upper bushing
• Synchronizer shaft
• Intake manifold assembly
• Air intake assembly

Cost of Repairing this Issue

The typical repair cost for just the parts ranges from $125-150. With professional labor and shop fees, expect a total cost between $350-500 to thoroughly diagnose and correct this noise concern. Costs may be higher if additional engine disassembly is required.