Chevy406

iTrader: (12)

Have any of you seen this kind of corrosion pitting in the valley cover around the knock sensor? Weird thing is, I checked it with a magnet, and it isn't magnetic. I'm suprised aluminum would pit like this. Maybe some type of galvanic corrosion caused by dissimilar metals? This was on an LQ4 from a 2001 PU. Where does the gasket seal off on the cover? I think I'll use another cover and can this one...

vettenuts

iTrader: (4)

What did the knock sensor look like?

There was a bulletin some time back about knock sensor issues with regards to water. The bulletin required a dam of RTC be made around the knock sensor hole to keep out water, especially if the motor ever gets washed.

01ssreda4

iTrader: (96)

wow, mine didnt look like that

budhayes3

iTrader: (19)

Very common, there's a TSB in reference to this for the trucks, so I'm assuming that the TSB applies to the cars also. GM wants you to seal off where the knock sensor connector goes into the valley cover with RTV and build a dam. I'd clean off the corrosion with some scotch brite and make sure that the connectors and knock sensors aren't corroded, you may want to replace the knock sensor sub-harness if it's in bad shape.

*EDIT* Just realized that vettenuts posted this exact info, sorry...