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Knock Sensor Replacement

Discussion in 'How-to Guides' started by KyleZ71, Jul 13, 2013.

  1. KyleZ71

    KyleZ71 New Member 100 Posts

    Hey everybody, as you have all seen I've had trouble with my knock sensor so as I replaced my knock sensors and sub harness I decided to take so pictures.
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    Lets start with my 5.3L engine
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    Take the engine shroud off and remove your air intake snorkel.
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    Remove the bolt holding in the sensor shown above. This is a 8mm bolt on my 2003 silverado
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    I found it easier to remove the intake manifold when the fuel rail with the injectors attached are removed. These bolts are 8mm as well
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    Disconnect the absolute pressure sensor
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    Remove the hose attached to the rear of the intake. It will has a red fitting onto which it attaches
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    Disconnect the knock sensor sub harness. When replacing the knock sensors it is wise to replace the complete sub harness as well as the replacements seal much tighter
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    Disconnect the harness leading to the throttle body
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    Disconnect the mini vacuum tube on top of the throttle body
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    Sorry for this being upside down. Disconnect antifreeze lines leading into the throttle body. My 03 5.3L had 3 lines running into it.
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    Showing the disconnected antifreeze (coolant) line
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    Loosen but do not remove the intake manifold fasteners. There are ten total, five on each side. You will need a 10 mm socket. I found it to be easiest using a wobble extension for the front three but using a knuckle with a regular extension for the rear two (on each side)
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    With the intake manifold loosen, shimmy and shake it loose by pulling it up and out. This is a good time to clean out the entire intake manifold with some intake cleaner. I would advise to replace your gaskets if they are old. Clean off the heads with a razor blade and some simple green.
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    I was surprised how much water was sitting in the back port for the knock sensor. After removing the knock sensor and replacing (would recommend) both sensors, attach the harness and run the fitting to the end of the block. Seal the rubber covers with black rtv to prevent water damage.
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    Here are two images. The first is a good knock sensor and the second is the severely corroded sensor that was throwing codes.

    Hope this helps anyone who runs into my problem. To re-install the manifold, just follow these procedures but in reverse.

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