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

[89Suburban]

I've torn these engines down and reassembled many times. I'll be pulling mine out and tearing it down to the shortblock very soon to replace the cam and lifters (AFM delete), all seals and gaskets, etc.

Valley cover gasket would be super easy and a half day job taking your time. I'd make it a full day job with all the extra studying and cleaning I'd be doing, particularly with the intake manifold. Having a "dry" intake manifold makes these things so easy to work on.


I don't know what your timeframe is looking like, but if I do mine before you do yours and if time allows, I'll try to remember to take pics of the process. I don't see myself being in a rush since I'm now planning on having my heads lightly worked over. That alone makes it a multi-week process instead of a one-weekender.


The basics off the top of my head:

Remove the beauty cover

Relieve the fuel system pressure and disconnect the lines

Remove the intake tube from the TB

Unplug the TB, all injectors and all sensors. The injector clips are about the hardest part of the whole process )

Loosen the IM bolts (they're captured so just loosen 'til they can be pulled up)

Remove the IM

Plug intake ports in heads with shop towels or painter's tape

Clean off valley cover

Remove valley cover bolts

Remove valley cover


I'd inspect the IM for oil in the back of it and thoroughly clean the TB and insides of the IM, including the runners with a baby bottle brush, engine degreaser, spray from the water hose nozzle, brake parts cleaner and blow dry with compressed air.

Thanks man!! should I replace the oil pressure switch and screen while it is apart? Do I have to worry about knock sensors in the cover? I seen that in some videos but I think that is for the vortex motors? Is there orings Under the cover? I hate typing on the damn phone!!!!

 

[wjburken]

Thanks man!! should I replace the oil pressure switch and screen while it is apart? Do I have to worry about knock sensors in the cover? I seen that in some videos but I think that is for the vortex motors? Is there orings Under the cover? I hate typing on the damn phone!!!!

Do you have AFM?

 

[89Suburban]

Do you have AFM?

Yeah the cylinder deactivation crap? Yeah. But I am running the range tech bypass thing. This motor has 319K on it.

 

[wjburken]

Yeah the cylinder deactivation crap? Yeah. But I am running the range tech bypass thing. This motor has 319K on it.

That’s the difference I believe. Your valley cover will look different. It will have a series of ridges for oil paths. The non-AFM covers are flat like the one in the video.

EDIT:
https://www.gmpartscenter.net/oem-p...MI-uPn_qTt5gIVyrzACh2JVQEREAQYAiABEgK00fD_BwE

 

[R3cord303]

Until recently, I didn't know the pf48E was a junk filter compared to the pf48. I went to the upf48 and cold starts are less noisy and my oil pressure is higher at idle, and stays around 38-42 at cruising speed. I swear my VVT is also working better too, but I don't have any official proof, unless my butt-meter counts? Haha

I haven't heard of the UPF48 before. What's the difference between the non-e PF63 vs the UPF63?

 

[R3cord303]

Thanks man!! should I replace the oil pressure switch and screen while it is apart? Do I have to worry about knock sensors in the cover? I seen that in some videos but I think that is for the vortex motors? Is there orings Under the cover? I hate typing on the damn phone!!!!

I have some AFM delete parts leftover from my new engine if you'd like to buy some of them. Totally down to let them go for super cheap. I've got a full set of rockers, a full set of lifters that are matched to a Jasper step up non afm camshaft, I think I've got a valley cover, a timing chain sproket, and I think even a full head gasket/timing cover gasket kit.

 

[trailblazer]

I haven't heard of the UPF48 before. What's the difference between the non-e PF63 vs the UPF63?

UPF is ACDelco’s premium filter. I use it in the C7. I stopped using those in my trucks when I could buy a case of Wix for $1.50 ea. I drive over 3,000/miles a month and I’ve never had a problem yet (I change oil every 3-4 mos). Buy in bulk if the price is right. Current RockAuto prices:
ACDelco PF48E $3.12, UPF48R $7.36

It’s funny how people that claim to be car snobs go to a drive-up quick lube only for them to install a $0.99 oil filter. But then I realize that it really makes no difference as long as the driver regularly changes the oil. Filter failures are so rare. I have only read anecdotes on the internet and heard many Old Wives Tales.


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[Geoffsfas10]

I feel bad interrupting all the good tech info here, BUT I installed the transfer case Z71 skid plate today....going to try and work on photos tomorrow or this week. Weather might hold out for me

 

[R3cord303]

UPF is ACDelco’s premium filter. I use it in the C7. I stopped using those in my trucks when I could buy a case of Wix for $1.50 ea. I drive over 3,000/miles a month and I’ve never had a problem yet (I change oil every 3-4 mos). Buy in bulk if the price is right. Current RockAuto prices:
ACDelco PF48E $3.12, UPF48R $7.36

It’s funny how people that claim to be car snobs go to a drive-up quick lube only for them to install a $0.99 oil filter. But then I realize that it really makes no difference as long as the driver regularly changes the oil. Filter failures are so rare. I have only rear anecdotes on the internet and heard many Old Wives Tales.


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I’ll get the UPF63 next time then! I’d be getting them anyway but I didn’t know they existed!

I feel bad interrupting all the good tech info here, BUT I installed the transfer case Z71 skid plate today....going to try and work on photos tomorrow or this week. Weather might hold out for me

I also got the skid plate for the front diff. Need the screws for it though which is the only reason I don’t have it on there right now.

Side note: I think the battery in the tahoe may have taken a shit. Slow crank this morning and it didnt start after I changed oil. Had to charge it for a few hours. Going to Autozone to have it tested now

 

[89Suburban]

That’s the difference I believe. Your valley cover will look different. It will have a series of ridges for oil paths. The non-AFM covers are flat like the one in the video.

EDIT:
https://www.gmpartscenter.net/oem-p...MI-uPn_qTt5gIVyrzACh2JVQEREAQYAiABEgK00fD_BwE

Ok I will check that out thanks friend.

I have some AFM delete parts leftover from my new engine if you'd like to buy some of them. Totally down to let them go for super cheap. I've got a full set of rockers, a full set of lifters that are matched to a Jasper step up non afm camshaft, I think I've got a valley cover, a timing chain sproket, and I think even a full head gasket/timing cover gasket kit.

I really REALLY appreciate the offer but that is a bit too much for me to handle.

 

[R3cord303]

Went to Autozone and they put their tester on the tahoe. Batterys real ****** up. Bought one of the Autozone Platinum AGM batteries. If money wasn’t so tight I’d have gotten two for a dual battery setup. Next time I will!

 

[89Suburban]

What is this oil line setup? In front of the valley pan. And what is that angled 10mm bolt right next to it sitting at an angle?

 

[wjburken]

What is this oil line setup? In front of the valley pan. And what is that angled 10mm bolt right next to it sitting at an angle?

That sure looks like your coolant crossover air bleed pipe to me.

 

[R3cord303]

What is this oil line setup? In front of the valley pan. And what is that angled 10mm bolt right next to it sitting at an angle?

That sure looks like your coolant crossover air bleed pipe to me.

+1 for coolant line. I wish I had seen this before changing that battery and I'd have looked at mine while I was out there to confirm. If it goes to the heads it is for sure a coolant line

 

[kbuskill]

What is this oil line setup? In front of the valley pan. And what is that angled 10mm bolt right next to it sitting at an angle?

The "oil line" is actually the crossover line for the steam ports on the heads.

 

[89Suburban]

Yikes

 

[iamdub]

Thanks man!! should I replace the oil pressure switch and screen while it is apart? Do I have to worry about knock sensors in the cover? I seen that in some videos but I think that is for the vortex motors? Is there orings Under the cover? I hate typing on the damn phone!!!!

If it's in the budget and especially if they're original- yes. Murphy's law says yours will fail soon after you have everything reassembled. Use an ACDelco brand sensor.

No knock sensors under the cover. The Gen 4 engine has the knock sensors bolted to each the side of the block, just above the oil pan.

Technically all of these are "Vortec" engines. What you were seeing is some Gen 3 and some Gen 4 videos. Your engine is a Gen 4.

O-rings under the valley cover? Yes. There's the main gasket and two different sizes of O-rings for the towers and solenoids. BTW, it's technically known as a "VLOM" (Valve Lifter Oil Manifold). I should mention that there's an updated VLOM. But, if you're not gonna use AFM, I'd guess your old one is fine since the solenoids aren't being cycled.

 

[iamdub]

I have some AFM delete parts leftover from my new engine if you'd like to buy some of them. Totally down to let them go for super cheap. I've got a full set of rockers, a full set of lifters that are matched to a Jasper step up non afm camshaft, I think I've got a valley cover, a timing chain sproket, and I think even a full head gasket/timing cover gasket kit.

You running aftermarket rockers on your cammed motor?

If the rockers are factory pieces, I may be interested in them if PawPaw isn't.

 

[89Suburban]

Any quick and easy fixes for this besides replacing the whole thing or using scotch tape? Any secret squirrel internet fixes?

 

[R3cord303]

You running aftermarket rockers on your cammed motor?

If the rockers are factory pieces, I may be interested in them if PawPaw isn't.

Yes! They are stock rockers. I dont know if they’re clones or oem gm ones. Whatever Jasper uses. I am running upgraded trunnion rockers. Texas Speed sells some on their site. Dont remember what brand.