Transmission fluid and filter change, temperature to check fluid level??

[XY74]

Coming up on 45K on my truck and it's time to change the transmission filter.  I read through the filling procedure and it says get the trans temp up to 165.  I barely ever recall seeing the trans temp as high as 165 in the summer towing my camper, so I am not too confident I can get it to warm up that much in the winter idling in the driveway.  Planning to measure what comes out, but that plan can always go awry if I bathe in the pan contents.    

 

Does anybody know how critical that temperature is to getting the fluid at an acceptable level?  I am assuming the warmer the fluid gets, the higher the level goes???  Would an extra pint really make much difference?  

 

Those pesky dipsticks, obviously they had to go!!!  

[elcamino]

I do not know for certain but when i had the GM dealer flush my this summer they mentioned it had to get up to 145° F to check it and that was taking more time.  I am sure that's an approximate.

 

2021 1500 10sp

Edited December 22, 2022 by elcamino

[64BAwagon]

I saw a technical bulletin a while back that gave the temp but I didnt save it and I dont recall exactly where I saw it. I believe it was something over 160 degrees. On most vehicles without a dipstick this is the time consuming part of the job. Plus once the trans is hot so are the cat's, one of which is near the side of the trans fill plug. The entire process is an epic fail in my opinion. The 1000 series was a breeze to service along with all the 3000 and 4000 series Allisons I ever worked with. Its my opinion that this is a strong indicator of GM's design. Take something that has always worked and make it much harder to maintain in order to save pennies. 

[redwngr]

I'm thinking the did away with the dipstick because there were so many that didn't check the level in the 6 speed using the instructions and ended up with incorrectly filled transmissions. 

 

Unfortunately removing dipstick inconveniences/harms those that do the servicing, level checks / adjustment correctly. 

 

 

It wasn't straight forward and simple. 

A cold check to confirm there is enough oil to run it to warm for the hot check. 

A hot check between 160 and 200F 

( I get that in many/most situations the cold check is likely skipped)

 

I don't know if this helps or hurts the discussion, but some may not be familiar with the procedure from the Allison used prior to intro of the 10 speed in 2020

 

From the 2018 Duramax supplement:  (this was the 6.6L with the speed Allison)

 

start cut and paste

 

How to Check

Because this operation can be a little difficult, the decision may be made to have this done by your dealer.

 

If the decision is made to perform this operation, be sure to follow all the instructions here, or a false reading on the dipstick could result. 

 

Caution
Too much or too little fluid can damage the transmission.

Too much can mean that some of the fluid could come out and fall on hot engine parts or exhaust system parts, starting a fire. Too little fluid could cause the transmission to overheat.

Be sure to get an accurate reading if checking the transmission fluid. 

 

Wait at least 30 minutes before checking the transmission fluid level if the vehicle has been driven:
. When outside temperatures are above 32 °C (90 °F).
. At high speed for quite a while.
. In heavy traffic — especially in hot weather.
. While pulling a trailer. 

 

Checking the Fluid Level

 

Prepare the vehicle as follows:
1. Park the vehicle on a level place. Keep the engine running.
2. With the parking brake applied, place the shift lever in P (Park).
3. With a foot on the brake pedal, run the engine for at least one minute and shift to D (Drive).

Then shift to N (Neutral) and then R (Reverse) to fill the hydraulic system.

Then, put the shift lever in P (Park).
4. Allow the engine to run at idle (500 – 800 rpm).

 

Slowly release the brake pedal.

 

Then, without shutting off the engine, follow these steps: 

 

Cold Check Procedure 

 

The purpose of the cold check is to determine if the transmission has enough fluid to be operated safely until a hot check can be made. The fluid level rises as fluid temperature increases. DO NOT fill above the COLD band if the transmission fluid
is below normal operating temperatures.

 

1. Pull out the dipstick and wipe it with a clean rag or paper towel.
The transmission dipstick is near the center of the engine compartment.

See Engine Compartment Overview pg 85 for location.

 

2. Push it back in all the way, wait three seconds, and then pull it back out again.

 

3. Check the fluid level reading.
Repeat the check procedure to verify the reading.

 

4. If the fluid level is within the COLD band, the transmission may be operated until the fluid is hot enough to perform a hot check. If the fluid level is not within the COLD band, add or drain fluid as necessary to bring the level into the middle of the COLD band. 

 

5. Perform a hot check at the first opportunity after the normal operating temperature of 71 °C (160 °F) to 93 °C (200 °F) is reached.

 

6. If the fluid level is in the acceptable range, push the dipstick back in all the way.

 

Hot Check Procedure

 

The fluid must be hot to ensure an accurate check.

The fluid level rises as temperature increases.

 

1. Operate the transmission in D (Drive) until the normal operating temperature of 71 °C (160 °F) to 93 °C (200 °F) is reached.

 

2. Pull out the dipstick and wipe it with a clean rag or paper towel.

 

3. Push it back in all the way, wait three seconds, and then pull it back out again.

Repeat the check procedure to verify the reading.

 

4. Safe operating level is within the HOT band on the dipstick.
The width of the HOT band represents approximately 1.0 L  (1.06 qt) of fluid at normal operating temperature.

 

5. If the fluid level is not within the  HOT band, add or drain fluid as necessary to bring the fluid level to within the HOT band.

 

6. If the fluid level is in the acceptable range, push the dipstick back in all the way.
Consistency of Readings Always check the fluid level at least twice using the procedures described previously.

Consistency is important to maintaining proper fluid level.

If inconsistent readings persist, check the transmission breather to be sure it is clean and unclogged.

If readings are still inconsistent, contact your dealer. 

 

end cut and paste

[redwngr]

On 12/22/2022 at 9:44 AM, elcamino said:

I do not know for certain but when i had the GM dealer flush my this summer they mentioned it had to get up to 145° F to check it and that was taking more time.  I am sure that's an approximate.

 

2021 1500 10sp

Should be easy to reach that temp with the 1500. 

 

[XY74]

Just turned 45K  I've been putting this off until summer and will just do the best I can to get it warm.  Knowing some of the people that call themselves dealer mechanics, it surely has to be close enough.  (no offense to the very competent ones!)  

 

We just traveled down I-77 in WV and VA and the highest the transmission ever got was 169, but was mostly staying in the low 150's.  The truck didn't care it had a lumbering 9000lb box tagging along.