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

[Fubar0715]

I get about 13 In thecopcar, but I do have AT tires and extra weight.

Still too early to tell with thethirdtwin.

Maybe that is the major difference...I am 4x4 on 20" wheels with ATs which contributes to the lousy mileage I suppose.

 

[89Suburban]

Ok toady's mission in this 90* humid ass swamp ass shit show is doing preventative maintenance and replacing the heater core tee's. Damn good thing I am, the outer straight connector nipple completely crumbled to dust in my hands. DAMN lucky on that one that it didn't happen on the road!!! Got brand new AC Delco replacements going in.

 

[iamdub]

How in the Sam Hell are you guys getting that kind of MPGs. When I drove to Florida, running 75ish all the way down, I got no more than 16. I would not give up my truck but a few more mpgs would be nice.

Drag is your biggest hindrance. Mine's 2WD (less weight), lowered and on stock-size street tires on lighter-weight wheels. The engine's also modded and tuned accordingly. All the engine mods were selected to work together. The higher compression increases power/torque. The tighter quench promotes more complete burn (efficiency) and reduces chance of detonation which allows for higher compression and more aggressive timing. The cam increases efficiency (read: power) notably at cruising RPM, reducing engine load at that RPM. Because of the improved power at the cruising RPM, I can get the same MPG at 72 as I do at 65 despite the higher RPM and increased wind resistance. Of course, it starts dropping considerably after 75 and 80 MPH- something like 1 MPG for every 2 MPH increase. The semi-tuned exhaust reduces pumping losses but maintains scavenging. The 3.xx"/4.xx" drop while maintaining a rake (although slightly reduced from stock) greatly improves aerodynamics. The removed roof rack helps a little. Removed third row seats so that's probably 100 lbs of weight reduction. This is also with a 3.73 axle gear.

 

[89Suburban]

Ok, here is a good example why taking pictures and studying them pays off instead of rushing the new parts on!!!

 

[Doubeleive]

How in the Sam Hell are you guys getting that kind of MPGs. When I drove to Florida, running 75ish all the way down, I got no more than 16. I would not give up my truck but a few more mpgs would be nice.

Just drive mine about 1000 miles almost all highway and all I ever get is about 11

 

[89Suburban]

Is it supposed to be black on the outside and white on the inside?

 

[Geotrash]

Is it supposed to be black on the outside and white on the inside?

I was going to make a silly remark about always being pink on the inside but decided not to. Sort of.

You’ll notice that there is a slight difference in diameter of one of the pipes so they’ll only fit either the inlet or the outlet of the heater core. On mine, it’s black on the outside and white on the inside.

 

[gooffeyguy]

Is it supposed to be black on the outside and white on the inside?

Not sure off the top of my head which one is which, but they do have a different angle for the small rear line to connect to.

 

[Fless]

On my '04 the white tee is closer to the engine, and the black tee on the passenger side.

Is that black o-ring (or what is that) supposed to be on the passenger side heater core fitting?

 

[gooffeyguy]

On my '04 the white tee is closer to the engine, and the black tee on the passenger side.

Is that black o-ring (or what is that) supposed to be on the passenger side heater core fitting?

I don't think all the pieces are off of them in that pic. Looks like parts of the inner clips still on the core pipes

 

[89Suburban]

Welp fuggit.

 

[George B]

Welp fuggit.


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I need to do this too. Almost fee like I should at least have the tees in the tool box, in the truck.

 

[RooTBeeRthe1st]

I need to do this too. Almost fee like I should at least have the tees in the tool box, in the truck.

Yeah, I've had those replacement hoses and fittings in the back for months now, haven't gotten around to it yet. Think now I'm just going to order a new coolant expansion tank and then do all of them at the same time... At that point, I think the only coolant hoses that could potentially give me a problem would be the ones for the rear heater all the way at the back.

 

[13UpInSmoke]

New to me 22" wheels with burnt copper dip. More pics & info on my build page

 

[Just Fishing]

I gave my almost 16 yr old son a go at a 5 speed manual knowing he will likely never have to drive one.

Not bad for the first time. Stalled, jerked, didn’t brake, stalled. Lol all good.

13 yr old daughter told me she wanted a 1994 Convertible mint green Bronco.

Ok… none of those all go together in OEM form in a single statement.

The girls looked online and found $60k-$250k for their line items.

Ummm… next.

Maybe a Jeep dad?

Atleast they are excited for it.

Blows my mind with kids these days having their drivers licenses as not being a priority.

Then with my dad, my sisters could have a nice car but he made them share.

Me, i got my own but it had to be a project.

I got the rx-7 that my sister beat on, i could have held out for a 4x4 truck or a jeep but i loved that car.

Sister was still mad because she couldn't get the mustang her fiends thought was cool because her 12 year old brother had to sign off on it as a project car.
Late 70s and early 80s mustangs were not cool.

I almost got a 67 mustang as the project, but i was 30min to late... lol

Good memories right there.

 

[gooffeyguy]

Just noticed the driver's side rear-most exhaust manifold bolt head is gone. There's no apparent leak yet, or at least one that I can hear.

Guessing I'll replace all the bolts sometime with ARP.

Has anyone kept the header bolted to the rest of the system and just removed the bolts attaching it to the head? Does that allow enough space to get the broken bolt out? I have vice grips and a mig welder, lol.

Plus a new gasket

 

[Just Fishing]

How in the Sam Hell are you guys getting that kind of MPGs. When I drove to Florida, running 75ish all the way down, I got no more than 16. I would not give up my truck but a few more mpgs would be nice.

I averaged 19 going up a canyon @ 70mph, but this is the new engine and full roller valve train.

Doing about 2k rpm the whole way, never needed to downshift!

Tune testing last year i got 22mpg going up that same canyon With a more aggressive tune from a 2500hd..

I'm curious how much better it will do with the 6.2 timing.

I'm running a 6.2 stock cam with 1.8 ratio full rollers.

Then that quench thing i keep going on about..

I loosened it from .037 to .040.

So far it seems like power was slightly affected, and my gas mileage suffered slightly.

When i swap out those lifters, I'm going from .040 quench to .050...

That will allow me to run regular 87 octane (i hope).

But i might not be very happy compared to how it is now.

I think i need to go back to the 2500hd timing and do the exact same canyon for a nice compare.

 

[Just Fishing]

Just noticed the driver's side rear-most exhaust manifold bolt head is gone. There's no apparent leak yet, or at least one that I can hear.

Guessing I'll replace all the bolts sometime with ARP.

Has anyone kept the header bolted to the rest of the system and just removed the bolts attaching it to the head? Does that allow enough space to get the broken bolt out? I have vice grips and a mig welder, lol.

Plus a new gasket

I never even noticed the broken bolt on my 5.3 until i pulled the heads.

I had my friendly neighborhood welder tack on a bolt head to extract it.

I tried using an easy out to start, but that bolt was in there..

after i broke the extactor i folded and called my welder up.

Lots of videos on youtube covering it, i sent him links before dropping the stuff off.

easy enough to pull the manifold, use an impact from underneath.

You will probably need to remove the o2 sensor.

I think part of what helps the removal was the heat when he tacked on the nut.
He said it came out with very little effort.

I used arp bolts and copper antisieze when reinstalling everything.

 

[gooffeyguy]

I averaged 19 going up a canyon @ 70mph, but this is the new engine and full roller valve train.

Doing about 2k rpm the whole way, never needed to downshift!

Tune testing last year i got 22mpg going up that same canyon With a more aggressive tune from a 2500hd..

I'm curious how much better it will do with the 6.2 timing.

I'm running a 6.2 stock cam with 1.8 ratio full rollers.

Then that quench thing i keep going on about..

I loosened it from .037 to .040.

So far it seems like power was slightly affected, and my gas mileage suffered slightly.

When i swap out those lifters, I'm going from .040 quench to .050...

That will allow me to run regular 87 octane (i hope).

But i might not be very happy compared to how it is now.

I think i need to go back to the 2500hd timing and do the exact same canyon for a nice compare.

How do lifters effect quench

 

[Just Fishing]

Is it supposed to be black on the outside and white on the inside?

Do you need pictures?
I should have some from when i did those tees.
When reinstalling I found my self scratching my head a little.
And i think it was the black the that seemed a bit loose fitting.
Made me question if i had it right.