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Discussion Starter · #1 ·
loud knock noise and vibration when hard stop occurs, only stops when shifted into neutral, but come back when shifted into drive and sitting. doesn't happen when driving. any idea?
 

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Where is the noise coming from exactly?

Wonder if this is related to your other post saying the truck stops running after about 20-30 minutes.

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1987 ford bronco
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23 Posts
Discussion Starter · #4 ·

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1987 ford bronco
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23 Posts
Discussion Starter · #5 ·
Where is the noise coming from exactly?

Wonder if this is related to your other post saying the truck stops running after about 20-30 minutes.

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this noise was happening pretty much since the day after I bought it, the engine dieing has only been happening for a little bit, im not sure thought.
The noise sounds like it could be coming from the front passenger side, almost as if the exhaust manifold was banging off the motor but there is no wiggle on it.
 

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Yo Kirk,
"loud knock noise and vibration when hard stop occurs, only stops when shifted into neutral, but come back when shifted into drive and sitting. doesn't happen when driving."
IF you can catch "it" knocking when "shifted into drive and sitting", have a helper behind the wheel with parking brake engaged, their feet on the brake pedal and preferably front bumper up against a wall or stout tree; and you with a mechanics stethoscope or garden hose section using it to find the perpetrator. Be wary of fan, belt(s), pulleys, hot engine, etc.

A WAG; Could be the smog pump, based on this in later year Broncos, but isn't directly related to your issue;
"Knocking Noise May Occur when Engine is Cold and under Acceleration could be coming from the Secondary Air Injection (AIR) Pump: TSB 96-7-27 for 95-96 Bronco, Econoline & F Series; "...Verify the knock noise is coming from the AIR Pump and install the correct AIR Pump Service Kit for the application. Refer to the following diagnosis and service procedures for details. Test drive the vehicle cold. The knock noise is most noticeable while the engine is under load at approximately 1500 rpm. The concern may be verified on automatic transmission-equipped vehicles by first setting the parking brake, and with the wheels chocked, starting the engine and placing the vehicle in gear. Verify the knock noise is coming from the AIR Pump by using a technician’s stethoscope while the engine speed is approximately 1500 rpm. THE NEW AIR PUMP IS ORIENTED IN A POSITION 180 DEGREES OPPOSITE TO THE PRODUCTION AIR PUMP. "


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Yo Kirk,
 
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