What did you do to your NNBS GMT900 Tahoe/Yukon Today?

George B

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Sooooooooo took the belt off, the AC doesnt have a tensioner so I left that alone and the noise is still very present. its very much sounding like cylinder 1 area as well. Its also super weird since the rhythm at which it makes sound, doesnt seem to match RPMs or belts or anything. so wildly confused still.
I bet its a turned lifter scrubbing. There was another recent thread with the same sort of sound. Will take some digging to find it.
 

George B

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Here’s another from my engine after a cheap lifter tray let a lifter twist in it’s bore just enough to scar the cam and chip the roller.

When you’re ready for the cam swap and start putting your parts list together, lots of people around here will help you out. I ended up with a cam motion stage 2 truck cam and I’m really happy with it.

Geotrash had the issue.
 

George B

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Sounds totally different to my old ears. @Geotrash's was ticking right along with the rpms; this one doesn't seem to do that.

Was the main belt removed, too, when you removed the A/C belt?
It does sound different and I agree on the rhythm being in tome with rpm. But, my mind imagines the roller turning or not turning randomly. I hope I am wrong and it’s something else!
 

Geoffsfas10

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Sounds totally different to my old ears. @Geotrash's was ticking right along with the rpms; this one doesn't seem to do that.

Was the main belt removed, too, when you removed the A/C belt?
So main belt was the only one i got off, this truck doesnt have the tensioner for the AC belt and i dont have the tool so it stayed on. The video sounds way more high pitched and in rhythm with the motor, where as i was letting it run yesterday the rhythm changes as the engine rpm stays constant. Hence the even more confusing it makes this. Its pretty loud, like embarrassed to drive it around loud, which is good thing Im not. Using my parents LBZ silvy for now.



I was looking thru the Texas Speed DoD kit, and there are some good cam options, my biggest thing is tuning, surprisingly few LS tuners around here, but I think I found a good one. Texas speed lists the stock 6.2 cam as compatible...which that outta be worth a couple smiles and butt dyno points.
 

Geotrash

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So main belt was the only one i got off, this truck doesnt have the tensioner for the AC belt and i dont have the tool so it stayed on. The video sounds way more high pitched and in rhythm with the motor, where as i was letting it run yesterday the rhythm changes as the engine rpm stays constant. Hence the even more confusing it makes this. Its pretty loud, like embarrassed to drive it around loud, which is good thing Im not. Using my parents LBZ silvy for now.



I was looking thru the Texas Speed DoD kit, and there are some good cam options, my biggest thing is tuning, surprisingly few LS tuners around here, but I think I found a good one. Texas speed lists the stock 6.2 cam as compatible...which that outta be worth a couple smiles and butt dyno points.
I’d still check that starter. One of the failure modes on these is the return spring on the starter gear breaks and allows the gear to bounce against the flywheel teeth. Pulling the starter on one of these is easy enough, and you can verify whether or not that gear is loose in there.
 
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Rocket Man

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I’d still check that starter. One of the failure modes on these is the return spring on the starter gear breaks and allows the gear to bounce against the flywheel teeth. Pulling the starter on one of these is easy enough, and you can verify whether or not that gear is loose in there.
Agree with this as well as the others who suggested pulling the ac belt to rule out the compressor. It sounds external to me as well. Sounds can bounce around the engine bays in these and you’d swear they’re coming from one place but they’re not.
 

Geotrash

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Swapped my bench seat for buckets in the 2012. @zmusclow drove all the way up from North Carolina with 2 kids in tow to do the swap. Thankfully it was raining cats and dogs which gave us a chance to practice our frustration tolerance. Lol.

Zack is a super nice guy, and an active duty Marine. Thank you for your service, sir!

29D7A95B-04D3-4DD8-AD51-B3BE54296AEA.jpeg
 

CaptainAmerica1

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Swapped my bench seat for buckets in the 2012. @zmusclow drove all the way up from North Carolina with 2 kids in tow to do the swap. Thankfully it was raining cats and dogs which gave us a chance to practice our frustration tolerance. Lol.

Zack is a super nice guy, and an active duty Marine. Thank you for your service, sir!

View attachment 386513
Looks awesome!
 

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