24 GMC 1500 3.0 transmission fluid change

Dani Sanghera · March 17

I have a 2024 GMC 1500 3.0 diesel max trailering. I am planning to do a transmission fluid change( remove pan and replace filter). I had a question about filling the tranmission fluid back. i watched some videos but got differnt methods. i listed the steps below if someone can confirm if these are right

1. once drained and pan and filter are put back/ replaced, fill until it starts to drip out

2. turn the truck on and keep filling and go through the gears P,R,N,D (not driving) and continue filling until it drips out again and put the fill plug in

3. Once the fill plug is in let the transmissions temp go to above 196(and then let it cool down to 167-176 degree , turn the truck off while i waot to drop in this range) once it has cooled down to this range I turn the truck on and i take out the fill plug out. once I take out the fill plug the fluid will come out a quite a bit like 1/2 qt to 1 qt bc it has expanded but this is normal right? Once it starts to trickle I put the the fill plug back in.

newdude · March 17

A must. The filter bolts are one time use. Use 24050764 bolt kit which will have the two filter bolts and then a couple others you won't need. The filter bolts happen to also hold the valve body in place, hence their one time use-ness.

Pan bolts are 93 lb in torque spec.

Filter bolts are :

First Pass:(44 lb in)

Final Pass: 128 degrees

There is a note per GM on diesel 1500 10 speeds:

For diesel applications, the transmission fluid level should be checked only after the TFT has reached or exceeded an operating temperature of 105°C (221°F). Once the TFT has reached or exceeded 105°C (221°F), let the temperature cool back down to 75-80°C (167-176°F) before checking the fluid level.

The level check plug is on the driver's side of the case, towards the rear. You can fill it from there with the engine OFF at first until it starts to pour out and get as much as you can in then so its not a dry start. Put the plug back in, fire it up and shift through the PRND and back (spend about 5 seconds or so in each position to properly fill). After that I would fill it until it comes out while running and then drive it and cycle the temps as indicated. After that, engine running again, PRND and back and then set the level again.

Edited March 17 by newdude

Dani Sanghera · March 17

1 hour ago, newdude said:

A must. The filter bolts are one time use. Use 24050764 bolt kit which will have the two filter bolts and then a couple others you won't need. The filter bolts happen to also hold the valve body in place, hence their one time use-ness.

Pan bolts are 93 lb in torque spec.

Filter bolts are :

First Pass:(44 lb in)

Final Pass: 128 degrees

There is a note per GM on diesel 1500 10 speeds:

For diesel applications, the transmission fluid level should be checked only after the TFT has reached or exceeded an operating temperature of 105°C (221°F). Once the TFT has reached or exceeded 105°C (221°F), let the temperature cool back down to 75-80°C (167-176°F) before checking the fluid level.

The level check plug is on the driver's side of the case, towards the rear. You can fill it from there with the engine OFF at first until it starts to pour out and get as much as you can in then so its not a dry start. Put the plug back in, fire it up and shift through the PRND and back (spend about 5 seconds or so in each position to properly fill). After that I would fill it until it comes out while running and then drive it and cycle the temps as indicated. After that, engine running again, PRND and back and then set the level again.

thanks for the reply, noticed u said TFT said to be at 221°F then cooled down but my transmission usually sits around 192-196 and the highest around 201. how would I get it that hot if it it barley goes to 201 on the hottest ive seen it. and at the end u said"engine running again, PRND and back and then set the level again. " by level are u saying to let the fluid come into a drip and that will be level?

newdude · March 18

13 hours ago, Dani Sanghera said:

thanks for the reply, noticed u said TFT said to be at 221°F then cooled down but my transmission usually sits around 192-196 and the highest around 201. how would I get it that hot if it it barley goes to 201 on the hottest ive seen it. and at the end u said"engine running again, PRND and back and then set the level again. " by level are u saying to let the fluid come into a drip and that will be level?

So after you intially fill it off, and then fill it running and then drive it to temp. When it comes down to the temp they actually want it set at, engine running, cycle the gears, you'll pull the plug again and if it needs more fluid, fill it until it runs. When the run changes to a trickle, its the proper final level.