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04 Chevy Tahoe 129k. 4.8L eng. Intake plenum and knock sensors.

  • Dtnel
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10 Oct 2019 03:47 #34134 by Dtnel
Well I finally got around to pulling the upper intake plenum last night to replace my knock sensors. Generally I don't like to go into vehicles but I said hey nothing ventured nothing gained as I like doing more of that Diagnostics side of things.

So I have some pictures I'm going to upload and my question is with the upper intake plenum is there anything I can do to get that crud cleaned out of there? Can I put it in a commercial steam Parts washer if I remove injector crossover Rail, the injector rails and the injectors? I'm sure I would definitely have to remove all sensors which that's not a problem.

Second question should I pull the Valley Pan and replace the gasket since I have already came this far down into it or just let it be?

3rd question is as you can see on the intake Runners there's a lot of build up from the fuel but you can also see the lines where the injector nozzles spray. Is that a typical spray pattern going down through the intake port on the heads to the valves or do the injectors need some serious cleaning?

I planned on running the GM fuel injection cleaning solution through the OTC tool after I get this done and then when I'm done with that replacing the plugs and wires as I should have replaced them about 30,000 miles ago

I know pushing them Rags down there and probably knock some credit loose so I do plan on blowing it out with a blowgun and then finding a fine-tooth adapter to put on my shop vac and sucking as much credit as possible out of there or use a toothbrush with a rag wrapped around it to get down there and clean things out.

I know in the number 2 cylinder a couple small pieces of dirt got down into the intake valve so I will definitely need to get them out.

Also is it worth it to go ahead and use a wire or soft bristle brush and throttle body or brake parts cleaner to clean the openings down in the head?

I don't believe it has any head gasket issues but I should have thought about it ahead of time and did a leak down test that way since I was going to be in there if it did fail I could just pull the head or heads if needed.

Also can I use a carbon scarper lightly in the areas that the intake gasket will mount to the head or just use a gun cleaning plastic bristle brush, roloc wheel lightly as to not damage the sealing surface on the head? Maybe use some spray cleaner to help with thy brushing or roloc wheel?

I've had this 15 , almost 16 yrs and never had engine issues and don't want to create any.

I also if possible plan on doing some before and after photos of the inside of the Piston cylinders when I do the cleaning as it would be interesting to see what's going on in there plus get a read on the plugs before I do the cleaning as well as the cylinder condition as it has had a little bit of a rough idle around 1900 RPMs but also keep in mind that I just put a new bank 1 sensor 1 O2 sensor in this because the heater voltage was out.

What promoted all this? I'll include the pictures of the knock sensors and you'll see.

Any advice would be greatly appreciated.

Photos are at the dropbox link below as the file sizes are to large for uploading to the forums post.


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