Strange noise on shut down

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Jan 4, 2008 | 03:47 PM

corvetteguy

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Senior Member

Joined: Nov 2007

Posts: 163

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From: pa

Strange noise on shut down

My 97 F150 4.6 auto makes a
strange whirring noise which seems
to wind down for 30 or so seconds
after shut off.
Any idea what it is?

Jan 4, 2008 | 03:59 PM

Bluegrass

Senior Member

Joined: Jul 2004

Posts: 6,200

Likes: 39

From: Easton, Pa.

A sensor that has vaccum applied and is leakng down after the motor is shut off. Normal. Most of the time you don't hear it.

Jan 4, 2008 | 08:10 PM

Bent6

Senior Member

Joined: Jan 1999

Posts: 724

Likes: 3

From: Great Lakes

It's just vacuum in the intake. To confirm this, just floor the gas pedal after the engine shuts off. Instead of a slow leak, all manifold vacuum will be gone instantly.

Jan 4, 2008 | 11:42 PM

Pheonixx

Senior Member

Joined: Oct 2007

Posts: 579

Likes: 0

From: Buffalo, NY

mine does this too, never noticed until i put on the aftermarket air filter and modded the airbox. if you have aftermarket intake you will notice the sound alot more than if you didnt have it.

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