10L80 - filled transmission at wrong temp???

[BlaineBug]

What does your trans temp normally run at? I'm still trying to wrap my head around why they would want you to check it at such a higher temperature then what it normally runs at. Since I'm assuming it's normal temp is below 212.

Probably the maximum temperature they'd expect it to operate at under load or towing.

 

[jyi786]

What does your trans temp normally run at? I'm still trying to wrap my head around why they would want you to check it at such a higher temperature then what it normally runs at. Since I'm assuming it's normal temp is below 212.

It can vary greatly. On a cold day like today, if I don't do spirited driving, it doesn't exceed 145F. Spirited driving, can reach 190F. Hot day and spirited driving, can reach 215F.

It's worth noting that I have never seen my transmission exceed 220F.

 

[15burban]

They definitely don't make anything easy anymore lol. To me it would just make a lot more sense to have to check it at normal operating temp, not having to power torque or drive spiritly to reach the temp it must be checked at.

 

[Trides]

Yep. In my thread from a few months back, I detailed all of it. In short, I dropped the pan, changed the filter, inspected the magnet, refilled, and then transfused with brand new fluid.

For fluid, I'm using exactly what my manual calls for: AC Delco ULV ATF P/N: 10-4107 (19352619).

The ONLY thing I can possibly think of is that I underfilled it. No fluid comes out of the check plug when I open it, even with the transmission at 176F.

I bought 20qts more, and will do a complete transfusion again this weekend. Since I already have a pump, I also bought the little adapter that hooks up to the check plug port so that I can fill it from there without having to open the case plug, since I do not think that is the right way to do it. Alldata says to use the check plug port. I'll overfill and then let it drain, and at the proper temperature this time (203-212F).

@jyi786 Recently had 10 speed transmission warrranty valve body replacement and they used 19352620 Dexron ULV fluid.

 

[jyi786]

@jyi786 Recently had 10 speed transmission warrranty valve body replacement and they used 19352620 Dexron ULV fluid.

That's exactly the same fluid that I used: the part number you specified is just the Canadian version.

 

[jyi786]

Another thread popped up today about the 10L80 harsh shifting/shuddering.

2018 RST 10L80 harsh shifting

@NickTransmissions currently experiencing harsh shifts into 7 at 30 mph and more pronounced at 60 mph when accelerating on on ramp. Tech has confirmed harsh shifts from 7 to 10 on road test. Reset and road testEd with no change to harshness. Installed new valve body, flushed converter, lines...

www.tahoeyukonforum.com

Seems like I need to reset the computer (unhook the battery) and then drive it softly for a few months to let it learn the shift points again....

 

[jyi786]

Update: drove it around today and it got worse: it's now also shifting really hard through gears. Also confirmed it's torque converter shudder for sure. Tach bounces up and down before and during shudder. Mainly goes away after 60MPH, but under that, it's hard shifting and shudder galore. It's basically doing exactly what the OP lists in this entire thread.

2018 RST 10L80 harsh shifting

@NickTransmissions currently experiencing harsh shifts into 7 at 30 mph and more pronounced at 60 mph when accelerating on on ramp. Tech has confirmed harsh shifts from 7 to 10 on road test. Reset and road testEd with no change to harshness. Installed new valve body, flushed converter, lines...

www.tahoeyukonforum.com

Plan now is as follows, all 3:

1. Completely replace fluid; 16 qts. from what I did last time wasn't enough, you need 24 qts. Funny enough, I replaced the transmission fluid, dropped the pan, and changed the filter only 8k miles ago, but when I checked it last week, the fluid was already dirty brown. It was NOT burned; I didn't smell anything funny or burnt.
2. Inject 2 tubes of Lubegard Trans Fixx.
3. Reset computer (disconnect battery and leave disconnected for at least 30 min).

If after none of this works, I will consult with a professional.

 

[Trides]

@jyi786 I don’t think unhooking the battery resets the transmission (TCU) computer as I have read that there is an extra fee to unlock the TCU when if you are tuning the engine with a program from HP Tuners If you want to tune the transmission also.

 

[jyi786]

Update: it's "fixed". Quotes for emphasis, because I don't know if it's the procedure I did, or if it was really the Lubegard Trans Fixx.

This time, I transfused 22 quarts. Prior, I only did 16 qts., and I don't think I did enough. Old fluid was still in there. I pulled the cooler lines and drained/filled 2 qts. at a time until what was coming out the cooler was cherry red. That was 20 qts. The last 2 qts., I mixed with 2 packets of the Trans Fixx. Then I ran the fluid fill check procedure. This is where I got confused.

I brought it up to 212F, and let it run a bit, then opened the check plug and I *thought* maybe just a bit would come out. But no....almost 2 FULL QUARTS came out. Since I had no idea just how much of the Trans Fixx I lost, I had a third backup, so I mixed it with about .20 qts. of fresh ULV, injected it (spilling a little in the process, of course), and cleaned/buttoned everything up.

The result? NO MORE HARD SHIFTING. NO MORE SHUDDERING. In lockup or any other condition. It's so smooth and engages so fast I almost ran into a rail while test driving. I test drove for 30 min.

I will test again tomorrow and update again.

 

[BlaineBug]

Glad to hear that it is "fixed" and I hope that it lasts. You may want to consider doing this again with a full fluid change, pan drop, and filter replacement every 40,000 miles or so - earlier than the "recommended" intervals.