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!!!  

[Z45]

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.  

[gmatx]

I know this is an old post but I'm adding some additional (corrected) information on filling with the correct amount of transmission fluid.

 

The transmission fluid level must be checked while the transmission fluid temperature as displayed on your truck DIC (driver information center) is between 167°F and 176°F. If the fluid is too cold, you will have too much fluid (over-filled), causing "fluid to overflow from the vent tube, possibly causing a fire that may result in serious bodily injury or severe vehicle damage, fluid foaming, or pump cavitation". If the fluid temperature is too hot, you will be under-filled, which will "cause premature component wear or damage".  Getting the transmission fluid to the correct level involves heating up the transmission to proper temperature (167°F-176°F), and then removing the pan plug on the bottom of the pan, while the engine is still running and the vehicle is level and in park. If fluid should start to flow out of the pan plug, let it flow until the flow reduces to a drip, then replace the plug.  If fluid does not flow out, add additional fluid through the side fill plug until fluid starts to flow out of the pan plug, and then wait for the flow to slow to a drip, and then replace the plug.  All of this information and more can be found in the following post, including some instructions/photos taken directly from the GM service manual:

https://www.duramaxforum.com/threads/10l1000-servicing.1010029/

[A Chap]

Even when I'm hauling a truck camper on mountain roads while towing a trailer mine stays in the mid to high 140's.  

 

[mihuntn]

6 hours ago, A Chap said:

Even when I'm hauling a truck camper on mountain roads while towing a trailer mine stays in the mid to high 140's.  

 

It doesn't take too many converter stalls to reach the 167-176 F temperature range. I drove around a bit and got my temp up to 145 F. Pulled in my garage and did 3 converter stalls (hold brake and keep RPM under 1500 for 10 seconds) to to reach 172. 

[Black02Silverado]

56 minutes ago, mihuntn said:

It doesn't take too many converter stalls to reach the 167-176 F temperature range. I drove around a bit and got my temp up to 145 F. Pulled in my garage and did 3 converter stalls (hold brake and keep RPM under 1500 for 10 seconds) to to reach 172. 

Yeah, that is what transmission shops do to get the temp up.  Mine runs 145°F max when ever I drive it, Never see it go any higher.

[Grumpy Bear]

With the 6L80 at then 192 TBV the check target was above that temperature. 

With the 6L80 with the 70C thermostat the target temp was just above that temperature. 

Kind of says that the trans just needs to be at operating temperature.  

[Newduramaxh*ar]

I just did mine 2 weeks ago. Fairly easy job. Hardest part to get proper level. It took about 12qts to fill. 

[Black02Silverado]

11 hours ago, Newduramaxh*ar said:

I just did mine 2 weeks ago. Fairly easy job. Hardest part to get proper level. It took about 12qts to fill. 

I take it you have a diesel?  Because the exhaust  that runs under the transmission can be a pain unless you drop the exhaust.

[Drainplug_fan]

1 hour ago, Black02Silverado said:

I take it you have a diesel?  Because the exhaust  that runs under the transmission can be a pain unless you drop the exhaust.

The 2022 2500 HD Duramax trans pan is largely unobstructed and there isn't an exhaust under it. 

 

I'm in a 2022 High Country with about 45,000 miles of fairly light duty on the odometer. I have lost confidence in the folks who did this owner's manual so I decided I would do the maintenance rather than wait like the schedule shows.

 

I am glad I did not wait. Based on this cycle and reading all the accounts of infant mortality and valve body back-orders, I will not wait long to do this again. 

 

The job is a pain because there is no drain plug for the pan, which means you have a pan full to the brim when you lower it. I used an assistant on a floor jack while doing this on the driveway. So, just for the folks who have never run the job, the link in the post above is going to show you the service manual procedures, including the need to do the torque stalls to get the unit to temp. I will just add a few things on what else to expect.

 

When I first got started, on a cold truck, I pulled the lower plug to see if there was fluid above the standpipe level. I got close to 2 quarts doing this, so that step saves it from spilling over when you lower the pan.

 

When the pan is lowered, because the volume of the flooded parts and filter stay up as the pan lowers, the fluid level in the pan lowers such that there is about a 1/2" gap to the top of the pan. If you keep the pan level, nothing spills. Some folks stop here and suction off some of that level. I just carefully lowered and removed the pan. You will need to lower and move slightly forward to avoid the obstructions to the rear. The recovered fluid totals out roughly 9 - 10 quarts.

 

Skipping forward to putting fluid back... 

Filling the unit using the fill plug in the case means you are well above the pan seam. It will now require about 13 quarts to see it start to leak out of the fill-plug hole, but when you start the motor it will allow you to add more for a total of 15 quarts that most of the better filter kits are giving you. The extra volume ends up being the fluid exchange that flushes the remaining volume that was sitting in the rest of the places like the torque converter, cooling lines, etc.. 

 

When the 15 quarts have been added, with the plug placed temporarily in the case and the motor running, I brought the system to normal (about 140), I then ran just a few stalls and brough the temp to between 168 and 172F and pulled the pan plug to allow the fluid to drain to the stand pipe. This happens quick enough that the dashboard TFT stays at about 172F.

 

The color of that fluid should look nice and red, not dirty or brown. If you get a chance to catch all that excess fluid in a clean container, you should see what looks like new fluid. If it is very dirty, looks like coffee, or full of chips, I would say you are in trouble. This procedure will spill back about 5.5 quarts, which means roughly 9.5 to 10 quarts have been retained out of the 15. 

 

Dear GM, not sure what the thought process was to omit a drain plug in the pan, or dipstick/fill tube so this could have been a civilized procedure, but tell that committee to think twice next time.

Edited September 12, 2024 by Drainplug_fan

[64BAwagon]

Superior solutions makes a drain plug kit that you can add if you drop the pan. 

I already have one ready for when I do mine. I plan to use a copper crush washer in place of the nylon one and then put a tack on the nut inside the pan to lock it onto the body of the drain. https://transpartswarehouse.com/k032-transmission-drain-plug-kit-made-in-the-u-s-a-universal-ford-gm-superior.html