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

[Charlie207]

FWIW, I'm giving serious consideration to doing exactly this, as my 187k mile Yukon with original AFM (disabled in tune, but parts present) engine is one day closer to failure every day. Except, I will buy a junkyard motor and do the work on a stand, while I continue to daily drive my Yukon. The short block on these can last quite a long time. If the compression and leakdown numbers look good, I say send it.

That's what I did last year. My 5.3 was still working fine, but it had ~180k on it, and was starting to consume some oil.

I stripped a Marketplace engine down to the block in my basement, and had a machine shop look it over. They are robust engines, and don't seem to need much to keep working.

 

[Charlie207]

what do you guys think this little seepage might be? oil pan or oil cooler line seal?
i'm thinking the oil cooler line seal and the oil is getting blown around.
View attachment 470649View attachment 470650

If you can get a 10mm on those two EOL cooler bolts, try to see if it's loose. Mine was like that and my mechanic buddy pulled the gasket out, cleaned all the surfaces and reinstalled the gasket after flipping it around (the Prime Directive didn't apply in this situation, because it was already seeping), and it's actually staying dry.

 

[j91z28d1]

I just figured I'd dump even more money into this damn truck instead of buying a Navigator. I wanted to do an AFM hardware delete because it is getting close to 200k miles and it had all the original parts so I could stop worrying about it. I wanted to supercharge it so it would be more competitive with something newer, but I sure wasn't going to do that with the original cam, lifters, valve springs, oil pump, timing chain tensioner, etc. I went with a mild aftermarket cam since I always regretting doing a stock cam when I did the AFM delete on our old Yukon and I let Matt Gower talk me into deleting the VVT as well. I also put LSA heads and head gaskets on it plus a trunnion upgrade, GMPP timing chain with LS2 dampener, Melling 10296 oil pump, BTR valve spring, BTR pushrods. I am having second thoughts about supercharging a 200k mile engine though, although I didn't see anything glaringly wrong with it, just the normal wear I expected to see, I didn't like how dirty the engine was inside even though I've been changing the oil every 3-5k miles with Red Line since I got it at 166k and I've had the oil pan off before to change the oil pan gasket. The Magnuson isn't crazy with only 6 PSI from a 1900 blower, but I can't help but feel like I should have found a used engine with at least half the miles. It looks nicer now with all the new parts and the LSA heads only had 42k miles and were super clean.

View attachment 470850

looks like an aluminum block. was it a 6.2 with rec port heads. and you went to lsa Cathedral port? that's an interesting swap.

feels like you've handled all the common failure points of the ls and 6psi shouldn't even stress the bottom end. as along as you don't butt the rings with crazy boost, I feel like this thing will last forever.


on a side note, I just hurt something in my ls3 car last trip, odd one I can't guess what it is, but probably valve train is my guess. only a 100k on the engine, no afm but it has lived a hard life. I only say that to say it's the cleanest engine inside. not a spec of varnash anywhere and it's never been apart and never run any cleaner thru it. but it's still tapping. so it doesn'te really matter. they either eat themselves or they don't. I honestly can't find any rhyme or reason for why some look clean and eat themselves others can look like mud and last for 300k.


enjoy the boost

 

[Charlie207]

I honestly can't find any rhyme or reason for why some look clean and eat themselves others can look like mud and last for 300k.

Mud protects from heat.

 

[91RS]

The engine is an L94 6.2L, the LSA heads are rectangle port.

 

[j91z28d1]

Mud protects from heat.
View attachment 470859

hahaha!

 

[Doubeleive]

If you can get a 10mm on those two EOL cooler bolts, try to see if it's loose. Mine was like that and my mechanic buddy pulled the gasket out, cleaned all the surfaces and reinstalled the gasket after flipping it around (the Prime Directive didn't apply in this situation, because it was already seeping), and it's actually staying dry.

I am going to pull it up on some ramps and see what's up when it stops raining

 

[j91z28d1]

The engine is an L94 6.2L, the LSA heads are rectangle port.

oh OK. I was thinking lsa was an older ctsv engine for some reason. I guess I never looked up lsa heads. I was thinking all rectangle port heads were the same till the ls7 jump. huh.

learned something new. I always think these ls engines are simple but so many little details.

 

[the_tool_man]

The engine is an L94 6.2L, the LSA heads are rectangle port.

What are the LSA heads worth over stock LS3 heads? I have a buddy who offered to port a set of LS3 heads. But if there's a better option I'm all ears.

 

[91RS]

Probably little to nothing, especially on an NA engine. A good CNC job would net more power. They’re basically the same except the intake valve has a slightly different angle and the casting is better. I bought them because they were available, super clean, came with rocker arms that already had the trunnion installed, and LSA valve covers I will be using on my SS. I wanted to buy another set of heads to clean up and swap the valve springs and have ready to go when I did the cam swap to save time. Now, I will sell my original heads.

 

[CMoore711]

@91RS If you didn't think you were "all-in" before, you definitely are now!

Did you complete the AFM delete and new cam install? How's it running?

 

[Rocket Man]

I finally fabricated a solution to something apparently only @mikez71 and I care about:

View attachment 470736

See the original post and my update here!

You’re supposed to hold the washer fluid button for a few strokes of the wipers, not just the first one. Why are you concerned that the washer fluid is being applied from the trailing side of the stroke, when on the down stroke it’s being applied on the leading side anyway? Hold the button down until there’s plenty of fluid on there, and then let the wipers work like they’re designed! Sheesh talk about a solution to a problem that doesn’t exist. That might be why nobody else cares. I don’t mind stating the obvious.

 

[91RS]

@91RS If you didn't think you were "all-in" before, you definitely are now!

Did you complete the AFM delete and new cam install? How's it running?

Yeah, I got it all back together and have been driving it for the tune. I’m happy with how it feels, 30hp doesn’t make much difference in a truck as heavy as this. Matt seems to have been correct so far, I’m not noticing much as far as the VVT being gone. It’s a pretty mild cam as I didn’t want it pushing too much with the stock LSA converter or super lopey. I wish the valve train wasn’t so noisy but I’m thinking I can only hear it so well since I didn’t do headers like my other two vehicles have so the exhaust isn’t as loud.

 

[mikez71]

Why are you concerned that the washer fluid is being applied from the trailing side of the stroke

Because you drag all the dry crap, scratching your windshield and embedding it into your wiper. Thought that was obvious.
Apparently GM and everybody else doesn't care. It's only a problem for the afflicted, like me and @Scrappycrow.

Granted, the wipers work. Perhaps the dry wipe is more effective, and it's just a placebo effect, idk..
But wiper blades seem happier when wet, imho.

 

[Charlie207]

Granted, the wipers work. Perhaps the dry wipe is more effective, and it's just a placebo effect, idk..
But wiper blades seem happier when wet, imho.

Yeah, it's weird that people think dry blades on a dry piece of glass, dragging dirt, bug guts, and other damaging debris across the thing is fine.

I've never had a car (out of like 15) that let the blades drag across a dry surface. It's a bad idea; ask your significant other, and see what they say.

 

[Scrappycrow]

You’re supposed to hold the washer fluid button for a few strokes of the wipers, not just the first one. Why are you concerned that the washer fluid is being applied from the trailing side of the stroke, when on the down stroke it’s being applied on the leading side anyway? Hold the button down until there’s plenty of fluid on there, and then let the wipers work like they’re designed! Sheesh talk about a solution to a problem that doesn’t exist. That might be why nobody else cares. I don’t mind stating the obvious.

I run the squirters for multiple swipes, but thanks for the "education," I guess.

"Leading" is relative to the motion of the wiper on the first swipe, not to the motion of the vehicle. That should have been obvious. I don't mind stating the obvious.

 

[kbuskill]

Got bored again... lol

Kbuskill's 2008 Burb LTZ "MOD" Thread

Pretty cool looking and I bet at a fraction of the cost of the Boost Auto new LED doorhandles they just unveiled. The turn signal flash of the handles is a winner! Like looking at my twin, minus some of the cool mods you have with the lighting. Very nice!! :peace: Yeah, the cost for the...

www.tahoeyukonforum.com

 

[14Tahoe]

Replaced the front and rear differential oil this past weekend. I first changed the factory fill at 100k miles using Valvoline Full Synthetic (squeeze pouch) OEM fluid was very dirty. This time, I went with their Premium Full Synthetic Extended Performance. The old fluid still looked nearly new, even after 65k miles of use.

 

[Charlie207]

It was a balmy 30°F this morning, so I opted to use the remote start while I pulled my suspenders on, and when I came out I noticed the rear defroster had been doing defroster stuff.

This was weird, because as long as I've owned the rig the rear defroster hasn't worked. I tested for continuity, blown fuses, relays, corroded connections, and/or signs that any ROUSes had munched on anything, but it all checked out fine.

I'll take the small victories.

 

[mikez71]

Hope I'm wrong... but I think your exhaust was doing the defrosting.