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Old 07-16-2017, 09:46 PM   #1
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Join Date: May 2014
Location: Mission BC
Posts: 310
Changing Knock sensors in an LQ4

I need to change the knock sensors and the harness in my 72 K10 LQ4 swap.
They were questionable when I installed the engine and I should have changed them then. Oh well, the question is do I need the foam rubber at the ends of the intake manifold? i have read that it's needed and also read it cause more issues than it solves..whats common practice?
1962 C10 Longbox LS 5.3 4L60E----Sold$$
2014 Ram 4x4 3500 Laramie Diesel..Momma's truck
2015 Ram 4x4 1500
1997 Boxster.
1972 K10 Custom Deluxe LS 6.0
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Old 07-17-2017, 12:49 AM   #2
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Location: Independence Mo
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Re: Changing Knock sensors in an LQ4

I dont think they really do much, but I usually put them back in anyway. I usually put some silicone around the knock sensor plugs before putting them in to keep any water from getting into the holes.
My '72 short bed build.

5.3 swap into my RUSTY '71 C10 (avatar truck)
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Old 07-17-2017, 07:40 AM   #3
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Re: Changing Knock sensors in an LQ4

I never put the foam back in . It is a dust and water shield . Does more for dust . One of the common problems for the knock sensors in the valley is water gets in and they rust . Like ls1nova said , silicone the plugs in and seal them and your good . Also in my mind the foam helps hold heat under the intake . Of coarse I am more performance oriented .
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Old 07-17-2017, 12:53 PM   #4
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Location: Saskatoon,SK,Canada
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Re: Changing Knock sensors in an LQ4

The info I got was to leave the back one out. Keep the front one to help keep crap from getting in on the front side. Build a dam on the front side of the sensors with silicone but leave an opening at the rear of the dam for the recess to drain. Silicone the grommets in and around the wires. The engine is usually angled to the rear and leaving the back out and the opening in the silicone dam lets any water that gets in drain out the back while the dam directs it around the grommet. A LOT of stuff can get past the intake runners from the sides. They are only sealed at the ports and you'd be amazed at the crap that washes down into the valley cover area under the intake.
Saskatoon, Saskatchewan
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