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

[swathdiver]

Y’all remember the airbag issue/seat position sensor I’ve been trying to figure out for the past month? Well i finally gave in and took it to the dealership. So apparently somewhere in the harness there’s a shortage. Go figure.

On another note. When i get my truck back I’m going to install this rear view mirror with camera myself. The rear camera is going where the oem camera is going under the tailgate. Should i just drill the camera directly or there or make so kind of plate to put the camera on, then mount under the tailgate.

If you take the piece off, you will see the indentations for the camera, the mount and the holes, or where they should be. They were fused in with melted plastic, no screws. I used RTV on my replacement panel and it still changed the view a little from the original position.

 

[Mickey_7106]

anyone know if we have CK or standard wiring? want to order some switchbacks and they have 2 versions. Tried going on to check but im not messing around in this cold weather lol

Do I have CK or Standard Wiring?

www.gtrlighting.com

 

[08z71bgm]

I did some oil passageway matching and flowing in the block.
Matched the pan to the block as well.

This last attempt, i also added some oil flow passages to the thrust bearing surface
that was per the instructions from the manufacture of my mains (mahle iirc)

I also have the high-pressure high-volume Melling oil pump (low pressure spring installed).
if anything, it has too much oil flow/volume.

One thing to note, oil pressure is nice and above 40psi at hot idle with a fresh main.
when the thrust surface starts to get worn, i notice the hot oil pressure starts to dip under 40psi.
but i can nearly pin the pressure gauge over 4krpm.

And even with the updated valve cover, and the 3/4in valve cover spacers.
I still get some oil in the catch can.
but only when the oil pressure spikes during a run.
Leading me to think i'm either flooding the heads with oil, or more likely it's spraying up and making it into the pcv.


Also noting that the high flow pump warning was included in the cylinder head manufacture instructions (AFR).
They mentioned that it's possible to flood the valve seals unless the heads were flowed for oil return.
No information on how to do that, however comparing the stock 799 heads they looked like the oil return was a tad better.

And on that, i did modify the lifter trays to help with the oil return, I didn't go crazy as i wanted to keep some oil in the trays.
but they have a path to balance oil between the lifters, and a quicker return path pointed in the center of the block.
In theory, it looked like a good idea.
If the engine comes apart again, i'm going to dump the high flow pump.
And probably go back to an unmodified tray setup.

I do recall that my oil pressure started going weird during engine break-in when trying to do an engine breaking cycle down a hill.
rpm went a little too high, but i ran with it until i saw the oil pressure fluctuate a little.

My issues probably started right around that time, i also had my engine breaking cut to near nothing right about then as well.
blaming that for the trans cooler passageways since engine breaking seems to have returned...
I haven't looked at flow paths in the 6l80, but it's a thing in the 4l60's.
Mostly it's that trans fluid gets cut off to the rear clutches or something along those lines.


I sorta want to pull the engine apart, it would be nice to see how it's doing...

I did get a good look at the cylinder bores from the underside view, and it looks fantastic.
Nice oiling, all cylinders look good.

I also have a spare set of head gaskets on hand.
I ran with a .037 quench instead of the safer ".040".

On one hand,
If it comes apart, i can lower the compression a little more.
(it's like 10.32 right now)

on the other hand, the engine runs great as is, throttle response is quick even with a cobbled together tune.
No real noticeable pinging, even with that low octane fuel i had in the tank.
Probably because of the tight quench...

So, if the engine comes apart, i'll loosen the quench, and lower the compression slightly with that...
Per my lil calculator, it drops it to 10.25 with the different gasket.


I don't really want to change the current setup, just make it work.
Low-end is fantastic, it's the perfect cruiser.
I also ran the 6.2 timing table for a quick run before the issues started, it's "OMG" good.
I'm worried if i lower the compression and loosen up the quench, i might lose some of that awesome low-end power i got.

(Sorry you got morning Chris thoughts/rambling )





Also, for anyone that builds engines might know if this is a problem
My crank has what i felt was a rough crank polish.
it's probably like 400-600 grit.

Then i used "race" bearings (tri metal).
the coating pretty much completely came off of the bearings.
still has the soft surface underneath.
I don't see any real thickness change, so i don't think it's an issue.

Just looking at my oem bearings, the coating is still there.
The crank seemed to also polish with the oem bearings.

My crank surface has no change...
I'm wondering if i needed a high polish on the crank for those race bearings.
Or am i just overthinking things?

I just finished building a 6.6L and I have close to 200 miles on my build. No noises or anything. I however didn’t reuse anything except my oil pan. Everything is new. Block crank rods the whole nine. My build when finished tuning should make around 750ish to the wheels.

If the surface on the polish is rough or turned the wrong way the crank journals now have like a circular saw blade effect on the bearings. It has teeth going into the turn instead of laying on the turn. This will most definitely eat up a bearing.

Think of like sharpening a knife. The tip rolls on the opposite side of the sharpened side right? Now has what we call a burr. Same applies to crank polishing. The burrs still exist after polishing but you need them to be roll over on the rotation not against the rotation.

There are tons of videos online that show this in great detail.

This is why when shopping around for machine shops you need to be mindful of experience and word of mouth not lowest price. Just making a statement. Don’t read into it.

I hope you get this fixed.

 

[Just Fishing]

Could that super-duper-mega-pressure-and-volume pump be sucking the sump dry, causing momentary loss of pressure that somehow affects that thrust bearing? Off the top of my head, this doesn't make sense since the lifters and all above get and lose pressure first. Still grasping at straws here.




What would be the benefit of lowering the CR and loosening the quench? Maybe a slightly larger window for a degree or three of timing at most. There's just no difference in that .003" extra piston space or 7 tenths of a point of compression to bother pulling the heads. Unless you have it apart for something else and those are the gaskets you have on hand. If those are your true CR numbers, you wouldn't even notice the difference.

It certainly has no relation to your thrust bearing woes.

I thought i saw signs of that during engine break-in.
when i still had the straight 30 weight break-in oil, oil pressure fluctuating badly.
I think it might have been an air suction situation due to how badly it fluctuated.
Only did that once, and for a very short time.

I also noticed about that time my engine breaking for the transmission going downhill was not nearly as effective.

I didn't notice the oil issue after i went to 5w30, maybe it flows better when hot?

#2 thrust bearing, i never ran the engine at a very high RPM, and the only oil pressure fluctuation i noticed was at hot idle.
And that was when i would pull the filter to check it, gut feeling told me it might be getting plugged.


For compression and quench,
I agree, No benefit for the lower cr and loosed quench.
I don't want to change it.

If it lowered a bit more, I might have a chance of running regular gas.
but it's not enough to make a difference.

So I'm hoping to avoid pulling the heads.
+ I have 60$ worth of brand-new coolant in that engine.

I'm sure I could catch most of it in a 5-gallon bucket, but here is hoping I don't need to pull the engine.

I also installed the heads with brand-new clean surfaces, I really don't want to mess with it.

Now if i wanted to change the camshaft for something more AFR head friendly (to make use of the flow a bit more), then it would be a good opportunity to do that.
But i really like the way it runs right now...

I also have those 1.8 ratio roller rockers i would have to factor any added lift to the 6.2 camshaft I installed.
(iirc i still have more wiggle room for even more lift if i did that)


anyways, wife ditched me today.
i have nothing to do.

So the plan is to get some propane filled, heat up the garage, and get that front axle removed!

then I'll see where the motivation takes me.


I also really miss my hoe.
my butt has been ruined by seats that are actually comfortable.


It's also funny,
I owe more $$ on the parts i spent to fix the hoe, than i do on the hoe itself.
Had it for a year, and it's more half paid off.
Should own it by this summer...

I'm tempted to talk to the bank about a refi, get those parts on a lower interest loan...
CC is like 6%
Hoe loan is 1.8%



When we bought the wife's car, they really wanted to sell us on a house refi to pay for her car, the hoe, and current debt.
Nice 10 year loan...

 

[Just Fishing]

I just finished building a 6.6L and I have close to 200 miles on my build. No noises or anything. I however didn’t reuse anything except my oil pan. Everything is new. Block crank rods the whole nine. My build when finished tuning should make around 750ish to the wheels.

If the surface on the polish is rough or turned the wrong way the crank journals now have like a circular saw blade effect on the bearings. It has teeth going into the turn instead of laying on the turn. This will most definitely eat up a bearing.

Think of like sharpening a knife. The tip rolls on the opposite side of the sharpened side right? Now has what we call a burr. Same applies to crank polishing. The burrs still exist after polishing but you need them to be roll over on the rotation not against the rotation.

There are tons of videos online that show this in great detail.

This is why when shopping around for machine shops you need to be mindful of experience and word of mouth not lowest price. Just making a statement. Don’t read into it.

I hope you get this fixed.

Yeah, I'm thinking about going with a different machine shop this time around.
The owner mentioned something about the nicks in the crank and how they got them most of the way out.
In my head I was thinking "there were no nicks in my crank?!"
I guess his Son did the machine work.

And looking at the journals, I could see signs of these "nicks"
Looked almost like someone took a punch to my crank.
Overall, I don't think it would cause an issue.
Decided to just trust them.

But this will be a balance only if the engine comes apart again.
And I will say, my engine is dead smooth running.
The balance job seemed good...
I also weighed each piston using a food scale, and double checked their numbers.

And I choose this machine shop since I have had prior experience with them, and i know a butt load of people that used them
Good reviews too.
Granted the experience I'm aware of, was high school for the years I was in the "advanced" auto class.
What was that 24 years ago?


But this makes me want to pull the engine even more...

I also remembered that I did buy a transmission pressure gauge a few years back, one that is meant to install permanently in the vehicle.
Bought it for the corvette, but I didn't like how big the gauge was.
So, in the vette, i went with an oil pressure gauge that maxes @250psi (close enough) in a smaller size to fit in an a-pillar gauge pod.

I need to figure out where i put that gauge.
It's totally getting installed in the hoe.

And my main reason for wanting to roll in a new bearing vs taking the engine apart, is I don't want to mess up a brand-new ($350) crank until I know the issue has been resolved.

 

[iamdub]

#2 thrust bearing, i never ran the engine at a very high RPM, and the only oil pressure fluctuation i noticed was at hot idle.
And that was when i would pull the filter to check it, gut feeling told me it might be getting plugged.

Yours has a #2 thrust bearing? We might've found your problem. lol

For compression and quench,
I agree, No benefit for the lower cr and loosed quench.
I don't want to change it.

If it lowered a bit more, I might have a chance of running regular gas.
but it's not enough to make a difference.

So I'm hoping to avoid pulling the heads.
+ I have 60$ worth of brand-new coolant in that engine.

I'm sure I could catch most of it in a 5-gallon bucket, but here is hoping I don't need to pull the engine.

I also installed the heads with brand-new clean surfaces, I really don't want to mess with it.

Now if i wanted to change the camshaft for something more AFR head friendly (to make use of the flow a bit more), then it would be a good opportunity to do that.
But i really like the way it runs right now...

I also have those 1.8 ratio roller rockers i would have to factor any added lift to the 6.2 camshaft I installed.
(iirc i still have more wiggle room for even more lift if i did that)

Even the stock LMG, at 9.6:1 compression, benefits from 89+ octane. At least, during hot weather. If you lowered the CR of your 6.0 to something more suited for ~87, you'd lose a lot of the peppiness you have now, even with the tune optimized.

You can change the cam without removing the heads by removing the rockers and spinning the cam a few times to push the lifters up into the trays, then sliding dowels (5/16" works fine) into the oil galleys to hold them while you swap the cam. Since you already have your rockers removed, you could slap on them 1.8s. Just be sure of your geometries. Oh, larger than stock cams tend to sacrifice small amounts of low end for mid-and upper-RPM power. That's just physics. They need a higher SCR to achieve a net DCR to make up for the losses. So, keep your CR and quench where you're at, unless them 1.8 rockers put you in the PTV danger zone.

 

[Rocket Man]

Yours has a #2 thrust bearing? We might've found your problem. lol




Even the stock LMG, at 9.6:1 compression, benefits from 89+ octane. At least, during hot weather. If you lowered the CR of your 6.0 to something more suited for ~87, you'd lose a lot of the peppiness you have now, even with the tune optimized.

You can change the cam without removing the heads by removing the rockers and spinning the cam a few times to push the lifters up into the trays, then sliding dowels (5/16" works fine into the oil galleys to hold them while you swap the cam. Since you already have your rockers removed, you could slap on them 1.8s. Just be sure of your geometries. Oh, larger than stock cams tend to sacrifice small amounts of low end for mid-and upper-RPM power. That's just physics. They need a higher SCR to achieve a net DCR to make up for the losses. So, keep your CR and quench where you're at, unless them 1.8 rockers put you in the PTV danger zone.

Word on the cam swap. I’ve done it twice like that, once in The Beast and I didn’t have to pull the blower or heads. So much easier.

 

[swathdiver]

Check your Drip Weatherstrips fellas!

The top portion is just friction fit, you can pull them up and clean under there and put them right back, wish I'd known this years ago.

 

[Rocket Man]

Check your Drip Weatherstrips fellas!

The top portion is just friction fit, you can pull them up and clean under there and put them right back, wish I'd known this years ago.View attachment 357711View attachment 357712View attachment 357713View attachment 357716

Holy sh*t that salt gets everywhere. I don’t have that problem here but I did find out about pulling that weatherstrip many years ago when I removed the side trim on the windshield in order to paint it. That looks like it’s gonna be a challenge to fix but at least you caught it before it’s too late.

 

[swathdiver]

Holy sh*t that salt gets everywhere. I don’t have that problem here but I did find out about pulling that weatherstrip many years ago when I removed the side trim on the windshield in order to paint it. That looks like it’s gonna be a challenge to fix but at least you caught it before it’s too late.

The only thing I could do from home quickly was to grind away the bad stuff and paint over it. Should buy a few more years. Eventually, a new section of drip rail will have to be fabricated and welded in.