75K tranny / transfer case service 2011 Tahoe

[Clive]

Serviced the Hoe on the weekend, transfer case flush/fill and tranny pan drop/flush. 75,000 miles, assume it's the first time. Figured someone might be interested to see the condition of the magnet shavings at 75K, imho it was needed based on the colour of the ATF. DEXRON VI btw, both tranny 6L80 and transfer case (NQH). Has the Z82/HD package, plus oil cooler/KNP.
Pan removal was aided with the use of a long clamp to pull the exhaust down that 1" to allow the pan to *just* clear the cross-pipe. Pan+magnet cleaned, new filter/gasket. Reinstall, then pushed total of 14qts through using a 3/8" pipe stuffed in the cooler exit pipe at the top of the radiator. Hold it in - it's under a fair bit of pressure and *will* pop out.... :-(
Good for another 50K !

Transfer case drain plug:-


Old ATF + dirty magnet:-

Clamp position to lower the cross-pipe to gain clearance:-

 

[swathdiver]

Good deal, now did you do the differentials? That girl is going to buck to and fro with clean fluid in the middle and dirty at the ends!

Now I know what to do with those wood clamps for things other than woodworking! Thanks!

 

[Clive]

Yep, diffs up next. 5 qts 75W-90 synthetic I think should be enough ? GU6/G80 on the rear. Unsure if 10 or 14 bolt yet...
What's the scoop regarding not using RTF with synthetic?

 

[swat2380]

Synthetic gear oil eats normal RTV. Permatex makes a synthetic gear oil sealant but alot of people reuse the factory gasket dry without issue. I just did a drain and fill but chose leave my rear cover sealed and pump the fluid out of the fill hole.

 

[swathdiver]

RTF? 10 bolt axles for 1500s. The rear takes 2.15 quarts or 2 quarts and 5 ounces. The front takes 80W-90 regular, not synthetic @ 1.51 quarts.

I've opened my rear differential twice this year and put the original gasket back on without sealant of any kind, just dried it with a rag. No leaks.

 

[NGAneer]

Synthetic gear oil eats normal RTV. Permatex makes a synthetic gear oil sealant but alot of people reuse the factory gasket dry without issue. I just did a drain and fill but chose leave my rear cover sealed and pump the fluid out of the fill hole.

x2

I used the permatex black RTV smeared on a replacement fiber gasket with no issues. Just let the permatex tack up a little before putting it on.

 

[Clive]

So did the front and rear differentials at 75K. A little over 4qts total Mobil-1 75W-90 Synthetic, 5+pts rear, and 3pts front. Rear diff has the fill plug in the cover rather than in the main housing by the driveshaft. 10 bolt, so 8.6", right? Mine took more than the 2.1qts/4.2pts listed - around 2.5qts or so... Reused the gasket which was in good condition.
Fill plugs had typical level of metal fillings. Not concerned, but glad I didnt wait until 100K to service them.

 

[CobraKing]

@Clive How'd the truck drive after also changing the differential fluids vs. just the transmission?

 

[JasonPAtkins]

RTF? 10 bolt axles for 1500s. The rear takes 2.15 quarts or 2 quarts and 5 ounces. The front takes 80W-90 regular, not synthetic @ 1.51 quarts.

I've opened my rear differential twice this year and put the original gasket back on without sealant of any kind, just dried it with a rag. No leaks.

I just got off of the phone with the dealership this morning, having called because I need to do my front. They said the old non synthetic 80w90 part number for front diff oil has been superseded by p/n 88900401, which if you search, is just full synthetic 75w90, same as the back.

 

[JasonPAtkins]

RTF? 10 bolt axles for 1500s. The rear takes 2.15 quarts or 2 quarts and 5 ounces. The front takes 80W-90 regular, not synthetic @ 1.51 quarts.

I've opened my rear differential twice this year and put the original gasket back on without sealant of any kind, just dried it with a rag. No leaks.

I'm not doubting your numbers, but curious where you got them? I ask because I just got done doing rear diff pinion seal and an axle seal/bearing. I put 2qt and 15oz in the diff after draining it, because I had read on some other forum that it needed almost 3 qts. I'm sure I overfilled it, I'm sure their number was wrong, because it filled all the way to the fill hole to take that 2qt 15oz. Now, however, the pinion seal is leaking more than it was before I changed it (it was minor before) and I'm wondering if it's just leaking, not because I had a bad seal or installed it wrong, but just because the oil level is too high, making the oil slosh against the seal. If that were true, maybe once a bit leaks out (down to the proper fill level) it might stop leaking on its own?