Swapping in 40k 4.8 in Moms '05 Z71 Tahoe

[CapitalTruck]

I got my truck back about a week ago. Runs great. Rev's are up on the highway obviously, its about 2100 at 65mph. However, I can deal with that. This thing feels like a pack mule now, which is exactly what I needed. Additionally, its really cool to have such better grade braking when downshifting now. I am quite glad I made this change. I bought a Hypertech speedometer calibrator. That only allowed for 4.10 as an option (not 4.11). That is dang close and it worked fine as is indicated by near perfect agreement between my cell phone GPS and the speedometer. Anyone have any failure or success stories with Yukon gears? I have about 250mi on the job, shop told me to bring it back at 500 for an inspection/break in fluid change. I'm going to ask them if it would be okay for me to do the diff oil changes (front and back) so I don't lose the truck for a day. I've done that job already twice on this truck in the past.

 

[Jarlaxle]

This Monday, will be swapping in a low mileage (40k) 4.8 Gen III LS, LR4 to be exact into Mom's 2005 Z71 Tahoe. Tahoe was a southern truck and has 240k miles. Last 3 years in New York, oiled yearly, and in great shape.

The 240k 5.3 in it has bad lifters, makes some violent upper end noises and is definitely down a couple of cylinders. I bought this little 4.8 for my Regal, but figured for her daily driving and use, a SBE low mileage motor would be perfect. Plus time was never on my side for getting this project going.

Since the motor is out, will be replacing:
- new serpentine
- valley cover gasket, knock sensors, knock sensor sub harness, knock sensor gaskets
- plugs and wires
- thermostat
- exhaust manifold gaskets with ARP hardware (stock LS bolts love to break)
- upper and lower radiator hoses (did heater hoses and those connectors earlier this year)
- oil pressure sensor
- manifold flange gaskets, studs and nuts
- PCV
- intake gaskets
- oil pan gasket
- oil pickup tube o-ring

Have a local tuner that will be able to flash a 4.8 Tahoe tune to the PCM. From what I've read, a 4.8 will run on a 5.3 tune but use lots of fuel.

This 240k 5.3 uses a quart or so over 5-6k OCI, has strong 40PSI of oil pressure at hot idle and has no bottom end noise. So I will pull the heads, new LS7 lifters, boost cam, pushrods, MLS head gaskets and we will be hitting it with a nice healthy 15lbs of boost and it'll go into the Regal. The rings have got to be worn about perfect for some boost. I'd feel a lot less bad about scattering the guts of a 240k motor versus a young gun. But I doubt that'll happen. Probably will make some good power out of that old girl.



Should be fun!

Maybe re-ring the 5.3 before boosting it?

 

[Jarlaxle]

I do more differential builds than most Mechanics.....You may have been given the "Go Away" price

If you want to run cheap parts....Go for it. I use & stand behind Yukon & OE only.

I replace ALL bearings & seals with top shelf stuff, Again.....My name is going on it & that means a lot more to me than being the cheapest guy in town.

Strange, Zoom, Motive, Richmond, Precision, I'd trust any of them. I recall my Gremlin ran Precision gears, and that car was pretty hard on the rear end even as lit as it was. (Caddy uses stock gears.)

While I have never used them, G2 seems to be popular.

 

[Jarlaxle]

I got my truck back about a week ago. Runs great. Rev's are up on the highway obviously, its about 2100 at 65mph. However, I can deal with that. This thing feels like a pack mule now, which is exactly what I needed. Additionally, its really cool to have such better grade braking when downshifting now. I am quite glad I made this change. I bought a Hypertech speedometer calibrator. That only allowed for 4.10 as an option (not 4.11). That is dang close and it worked fine as is indicated by near perfect agreement between my cell phone GPS and the speedometer. Anyone have any failure or success stories with Yukon gears? I have about 250mi on the job, shop told me to bring it back at 500 for an inspection/break in fluid change. I'm going to ask them if it would be okay for me to do the diff oil changes (front and back) so I don't lose the truck for a day. I've done that job already twice on this truck in the past.

I would get a magnetic fill plug for at least the rear differential.

 

[clinebarger]

Strange, Zoom, Motive, Richmond, Precision, I'd trust any of them. I recall my Gremlin ran Precision gears, and that car was pretty hard on the rear end even as lit as it was. (Caddy uses stock gears.)

While I have never used them, G2 seems to be popular.

Yukon "laps" their gears in.....They catch any noise concerns before the gear set leaves their facility.

 

[Jarlaxle]

Yukon "laps" their gears in.....They catch any noise concerns before the gear set leaves their facility.

Never had noisy axle gears unless someone had run them with very low oil.

 

[clinebarger]

I've had some noisy Motive's & Richmond's in the past, Not to say every one will have issues or I had issue with every one I installed.