The knock sensor replacement project....
 

Finally on the home stretch..... taking a break for a few. I've done this before on my GMC Sierra but in a less involved way. On looking closer at the engine on this truck I came to realize that at some point in its life a prior owner maybe was confused about where the oil should go so they just poured it over the top. :confused: So I had a LOT of cleanup work to do as well while I'm in here. To just do the intake gaskets and knock sensors I could do the whole project in about 4 hours without bothering with much cleanup or anything.

I'm over 12 hours into it now but I am doing quite a bit more...

I also have an oil leak which could be any number of things. After basic cleaning of the engine a couple of weeks ago I concluded that the valve covers were likely leaking some. But there could be other places that are common on the LS engines like the oil pressure sender (behind the intake), cam position sensor (right next to the oil pressure sender), valley cover, valve covers, rear main seal, crankshaft position sensor, oil pan and a couple of other spots.

So I figure while I'm going in deep enough to replace the knock sensors I may as well go a tiny bit deeper and pretty much cover the top end to the head. So I got a gasket set that included valve cover gaskets, valve cover bolt seals, intake manifold gaskets, injector o-rings, and the valley pan gasket. Still had to get the valley pan knock sensor seals, knock sensors, knock sensor harness, etc.

Once I had everything off (about 2.5 hours) I figure the valve covers look terrible so I may as well give em' a coat of paint and purty them up a little. VHT metallic red engine paint sounded good and would match my fat new red spark plug wires.

So anyways - here are a couple of pics. I'll post a couple more later after I'm done. It does help having a 4000sf shop with all the tools I need too. This will finally get rid of the check engine light for the knock sensor thank god. Should also get a very nice improvement in performance and fuel economy. I've been averaging right at 9mpg with the bad knock sensor. :( The rear one was just as I had expected too. Full of water and rusty crud. The last shot shows after some reassembly. You can see the new knock sensors are nor completely sealed in from any future water intrusion.

https://www.hummerforums.com/forum/a...1&d=1489881800

https://www.hummerforums.com/forum/a...1&d=1489881800

https://www.hummerforums.com/forum/a...1&d=1489881800

Finally finished it up last night...... Had to make a 150 mile round trip this morning to go meet another H2 owner who had a set of original chrome H2 wheels (including the non-chrome spare) for $400.

Reset my average economy before I left and am happy to report that my average economy has gone from 9.1 mpg to 11.8 mpg. Granted I'd still like to improve that some more but I do tend to drive a bit fast averaging right about 80 mph. With the aerodynamics of a brick, the faster you go the worse the economy is going to get. Its just physics. Had I averaged 70 mpg I likely would have been well over 12 mpg.

That being said - when I had everything apart I also cleaned out the intake manifold. I removed everything from it and dropped it into about 7 gallons of new purple power and soaked it, flipped it, brushed with long brushes, etc throughout about a 6 hours period. The purple power ended up pure black and the amount of crap that came out of the intake was just amazing. Anyone that says a catch can only really benefits the newer direct injection engines has never looked very deep into the first few generations of the LS engines....

Not only is that crap clogging up your intake and heads its also heavily coating your valves. The thickness of the crud was easily 1/16" in places and is thick, gooey and sticky. Another thing is what does not stick to everything, you are burning which (albeit very slight) further reduces your economy due to the reduction in octane and combustability.

I cleaned out what I could in the runners in the heads but thats not easy to do without knocking crap down on top of the valves. It was also very obvious that my fuel injectors are very dirty. The nozzle plates were dark brown and more crud was all caked around the edges of them. I'm going to order a professionally cleaned and flow matched replacement set soon. That should also help some. I'll post an updated pic soon.

That looks great. The painted valve covers look nice.