What did you do to your NBS GMT800 Tahoe/Yukon Today?

[Rocket Man]

Probably so, nothing would surprise me now after seeing this crap.
Here's what my pan looks like now after a few minutes of scrubbing it with some LA Awesome from Dollar Tree. That stuff is the ****. I'm not done with it though, I'm gonna give it at least one more scrub. I need to find my wire brush so I can get the spots in the corners that I missed.
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What a difference !

 

[ScottyBoy]

What a difference !

Yep. And seriously, all I used was some LA Awesome, some hot water, and a stainless steel scrubbie. I did scoop out all the thick mud like sludge first though with my gloved hand.

BEFORE:

AFTER:

 

[ScottyBoy]

Also, the tool Gods blessed me today. I found a 10mm Snap-On mid length socket wedged between my oil pan and the wiring harness that run right alongside it. Must be from the transmission shop that worked on my truck a little over a year and a half ago, because I can't remember anyone else besides myself working on my truck in the last few years. If it was a USA made Craftsman, then I would assume it to be mine, lol Because that's what most of my sockets are. They are all from the 90's and early 2000's when Sears actually still had them made in USA.

 

[ivin74]

They didn’t fill at all or they didn’t raise the truck? If they filled until they feel solid (squeeze test) but didn’t raise it, either the ride height sensors aren’t telling it to raise it more or the compressor is bad.

They did not fill at all, the compressor tried filling them, then shut down right after.

 

[clandr1]

I purchased the truck in 2005 with 51k miles on it. Since then I have ALWAYS ran either Mobil1 full synthetic, or Amsoil XL series synthetic. No high mileage formulations. Longest I've ever gone was 7500 miles on an oil change, but when I saw how bad the oil looked I stopped doing that and changed it about every 5k miles ever since. It currently has 160k miles on it. I don't put a lot of miles on it, so a few times I've gone a year on the same oil because I didn't even put 5k miles on it. I wonder if sheer age of the oil is causing sludge?
Oh, and I've probably put about 40k miles on it since I last had this oil pan off in 2017. I also replaced the valve cover gaskets around the same time, and the top end of the engine appeared to be pretty clean.

That's very strange. I'm the original owner and have been running Mobil 1 High Mileage since around 75k miles, and I do not change the oil until the truck computer tells me to (generally 6-8k miles, depending on driving conditions). I've sent oil samples at least annually to Blackstone Labs since the truck had around 130k on it, and they've always come back looking good.

I dropped my pan and replaced my pickup tube o-ring in December 2017 when the truck had around 170,000 miles on it, and at that time it was sludge free.

I just can't figure out what's going on with yours - it seems the only difference is I've been using high mileage oil and you haven't, but I can't imagine it would cause sludge buildup like you're experiencing.

 

[clandr1]

I'm a day late, but yesterday I returned from a trip to San Antonio to visit the Riverwalk and Sea World with my wife and sons. It was around 650 miles round trip, about 5 hours each way. The truck cruised between 70-85 mph without any issues at all.

In fact, I rolled 232k on the trip. Guess I need to update my signature again...

 

[ScottyBoy]

I just thought about something. I installed a K&N air filter about 2yrs ago. I've been hearing mixed things about them. Now I'm wondering if maybe it "allows more dirt" to get into the engine, therefore creating more sludge? I dunno, just wondering about every possible scenario that could cause that crap to build up in my engine like that...........

 

[Walchit]

Probably so, nothing would surprise me now after seeing this crap.
Here's what my pan looks like now after a few minutes of scrubbing it with some LA Awesome from Dollar Tree. That stuff is the ****. I'm not done with it though, I'm gonna give it at least one more scrub. I need to find my wire brush so I can get the spots in the corners that I missed.
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Did you put that pan back on yet? I wish I would have changed the little oil level sensor when I had mine out. Because now I get a check oil level message sometimes.

 

[ScottyBoy]

Did you put that pan back on yet? I wish I would have changed the little oil level sensor when I had mine out. Because now I get a check oil level message sometimes.

No, I probably won't get it back together until this weekend. This is a multi day job for me. I still have to pull the timing cover and replaced the oil pump. Yeah, I could probably get away with just changing the pickup tube/screen but I already bought the new oil pump and timing cover gasket set. Plus my timing cover is leaking. So I may as well go ahead and change it all like I originally planned to. And yes I'm planning on replacing the oil level sensor as well, I already bought a new one as I was getting random "Check oil level" messages on my dash. But now I see with all that sludge and gunk in there, the sensor was just gummed up and sticking. So the sensor is most likely fine, but like l said I already bought the new sensor.

 

[clandr1]

I just thought about something. I installed a K&N air filter about 2yrs ago. I've been hearing mixed things about them. Now I'm wondering if maybe it "allows more dirt" to get into the engine, therefore creating more sludge? I dunno, just wondering about every possible scenario that could cause that crap to build up in my engine like that...........

I think there'd have to be a gaping hole in the filter to get enough dirt to cause that much sludge. I would recommend using a high mileage oil (I would suggest Mobil 1 brand since it's worked well for me) and see if your sludge issues continue. That's the only difference obvious to me between your sludge issue, and my lack of sludge.