Trans fluid drain and fill (2018 8-speed)

[dakotadodge80]

I am getting ready to do my first drain and fill on my 2018 1500. Dropping the pan doesn’t look too bad, but I was thinking about using a fluid extractor. Either way, it looks like a pain to fill since the fill plug is right above the pan and there is no dipstick tube. My main question is do you all go through the specific procedures after refilling it to check the level, or do you just put the same amount of fluid in that came out? I know I need to use the mobile one synthetic blue label.

[newdude]

1 hour ago, dakotadodge80 said:

I am getting ready to do my first drain and fill on my 2018 1500. Dropping the pan doesn’t look too bad, but I was thinking about using a fluid extractor. Either way, it looks like a pain to fill since the fill plug is right above the pan and there is no dipstick tube. My main question is do you all go through the specific procedures after refilling it to check the level, or do you just put the same amount of fluid in that came out? I know I need to use the mobile one synthetic blue label.

 

 

You could do it that way (same amount out, same amount in) but transmissions are very sensitive to fluid level for their operation so I would 100% check the level.

 

The fill port is where the dipstick would be if it had one.  Right hand side of the case, has a plug that you pull out.

 

Fill Tube Plug Method

1. Based on accessibility, transmission fluid may be added through the fluid fill tube plug assembly (1) hole or through the oil level check plug (2) hole in the bottom of the transmission fluid pan.
2. Clean around the fluid fill tube plug (1).
3. Unlock the fill tube plug by lifting the plunger. Once the plunger is lifted, remove the entire plug assembly (1).
4. Determine the approximate amount of fluid needed to fill the transmission, based on the repair performed. Refer to Approximate Fluid Capacities. To avoid an under-fill condition, slightly overfill the transmission, and then allow the extra fluid to drain out through the oil level check plug during the transmission fluid level and condition check procedure.
5. Using a pneumatic air fluid dispenser pump tool or a suitable hand pump, add transmission fluid through the fill tube plug opening.
6. Check the fluid level. Refer to Transmission Fluid Level and Condition Check.

 

 

Level check instructions.  You do have the thermostat so follow the note in red below to properly set the fluid level: 

 

• If vehicle is equipped with a thermal bypass valve, the transmission fluid level should be checked only after the TFT has reached or exceeded an operating temperature of 90°C (194°F). Once the TFT has reached or exceeded 90°C (194°F), then turn OFF the vehicle and allow the TFT to cool back down to 35–45°C (95–113°F) before checking the fluid level as required.  Reaching or exceeding an operating temperature of 90°C (194°F) opens the bypass valve and allows the cooler to fill up with fluid, which will result in a more accurate fluid level check.

 

Caution: THE ENGINE MUST BE RUNNING when the trans oil level check plug is removed or excessive fluid loss will occur, resulting in an under-filled condition. An under-filled transmission will cause premature component wear or damage.

Note: Continue to monitor the TFT. If the TFT is not within the specified values, reinstall the trans oil level check plug and repeat the previous steps.

Caution: Refer to Fastener Caution.

1. Observe the TFT using the driver information center (DIC) or a scan tool.
2. Start and idle the engine.
3. Depress the brake pedal and move the shift lever through each gear range. Pause for at least 3 seconds in each range. Move the shift lever back to PARK. Ensure the engine RPM is low (500–800 RPM).
4. Allow the engine to idle for at least 1 minute.
5. Raise the vehicle on a hoist. The vehicle must be level, with the engine running and the shift lever in the PARK range.
6. Remove the transmission oil level check plug (1) from the transmission fluid pan. Allow any fluid to drain.
   • If the fluid is flowing as a steady stream, wait until the fluid begins to drip.
   • If no fluid comes out, add fluid until fluid drips out. Refer to Transmission Fluid Fill Procedure.
7. Inspect the fluid color. The fluid should be red or dark brown.
   • If the fluid color is very dark or black and has a burnt odor, inspect the fluid and inside of the bottom pan for excessive metal particles or other debris. A small amount of “friction” material in the bottom pan is a “normal” condition. If large pieces and/or metal particles are noted in the fluid or bottom pan, flush the oil cooler and cooler lines and overhaul the transmission. If there are no signs of transmission internal damage noted, replace the fluid filter assembly, repair the oil cooler, and flush the cooler lines.
   • Fluid that is cloudy or milky or appears to be contaminated with water indicates engine coolant or water contamination. Refer to Engine Coolant/Water in Transmission.
8. Reinstall the transmission oil level check plug and tighten to 9 Y (80 lb in).
9. Inspect for external leaks. Refer to Fluid Leak Diagnosis.

[dakotadodge80]

Thanks so much! This is a bit confusing though. I need to start the engine and let it come to temp, then turn it off to cool down, then restart it to do the actual check? Is the check plug removed during the initial warm up?

[mikeyk101]

21 hours ago, newdude said:

 

 

You could do it that way (same amount out, same amount in) but transmissions are very sensitive to fluid level for their operation so I would 100% check the level.

 

The fill port is where the dipstick would be if it had one.  Right hand side of the case, has a plug that you pull out.

 

Fill Tube Plug Method

 

1. Based on accessibility, transmission fluid may be added through the fluid fill tube plug assembly (1) hole or through the oil level check plug (2) hole in the bottom of the transmission fluid pan.
2. Clean around the fluid fill tube plug (1).
3. Unlock the fill tube plug by lifting the plunger. Once the plunger is lifted, remove the entire plug assembly (1).
4. Determine the approximate amount of fluid needed to fill the transmission, based on the repair performed. Refer to Approximate Fluid Capacities. To avoid an under-fill condition, slightly overfill the transmission, and then allow the extra fluid to drain out through the oil level check plug during the transmission fluid level and condition check procedure.
5. Using a pneumatic air fluid dispenser pump tool or a suitable hand pump, add transmission fluid through the fill tube plug opening.
6. Check the fluid level. Refer to Transmission Fluid Level and Condition Check.

 

 

Level check instructions.  You do have the thermostat so follow the note in red below to properly set the fluid level: 

 

• If vehicle is equipped with a thermal bypass valve, the transmission fluid level should be checked only after the TFT has reached or exceeded an operating temperature of 90°C (194°F). Once the TFT has reached or exceeded 90°C (194°F), then turn OFF the vehicle and allow the TFT to cool back down to 35–45°C (95–113°F) before checking the fluid level as required.  Reaching or exceeding an operating temperature of 90°C (194°F) opens the bypass valve and allows the cooler to fill up with fluid, which will result in a more accurate fluid level check.

 

Caution: THE ENGINE MUST BE RUNNING when the trans oil level check plug is removed or excessive fluid loss will occur, resulting in an under-filled condition. An under-filled transmission will cause premature component wear or damage.

Note: Continue to monitor the TFT. If the TFT is not within the specified values, reinstall the trans oil level check plug and repeat the previous steps.

Caution: Refer to Fastener Caution.

1. Observe the TFT using the driver information center (DIC) or a scan tool.
2. Start and idle the engine.
3. Depress the brake pedal and move the shift lever through each gear range. Pause for at least 3 seconds in each range. Move the shift lever back to PARK. Ensure the engine RPM is low (500–800 RPM).
4. Allow the engine to idle for at least 1 minute.
5. Raise the vehicle on a hoist. The vehicle must be level, with the engine running and the shift lever in the PARK range.
6. Remove the transmission oil level check plug (1) from the transmission fluid pan. Allow any fluid to drain.
   • If the fluid is flowing as a steady stream, wait until the fluid begins to drip.
   • If no fluid comes out, add fluid until fluid drips out. Refer to Transmission Fluid Fill Procedure.
7. Inspect the fluid color. The fluid should be red or dark brown.
   • If the fluid color is very dark or black and has a burnt odor, inspect the fluid and inside of the bottom pan for excessive metal particles or other debris. A small amount of “friction” material in the bottom pan is a “normal” condition. If large pieces and/or metal particles are noted in the fluid or bottom pan, flush the oil cooler and cooler lines and overhaul the transmission. If there are no signs of transmission internal damage noted, replace the fluid filter assembly, repair the oil cooler, and flush the cooler lines.
   • Fluid that is cloudy or milky or appears to be contaminated with water indicates engine coolant or water contamination. Refer to Engine Coolant/Water in Transmission.
8. Reinstall the transmission oil level check plug and tighten to 9 Y (80 lb in).
9. Inspect for external leaks. Refer to Fluid Leak Diagnosis.

Question, I know this is the procedure for transmission fluid check for the 90⁰ C thermostat bypass valve. Let's say you have installed the updated 70⁰ C (158⁰ F) valve or even did the pill flip, how would the instructions be changed or modified to account for this?

[newdude]

On 12/21/2024 at 9:05 AM, dakotadodge80 said:

Thanks so much! This is a bit confusing though. I need to start the engine and let it come to temp, then turn it off to cool down, then restart it to do the actual check? Is the check plug removed during the initial warm up?

 

 

Yes.  That's so it fills the cooler lines and the transmission cooler so the level is properly set.  When the bypass valve opens up it will flow to the cooler.  When you shut off and it cools down, the valve closes so there will be fluid in the cooler and the lines that has to be accounted for.

 

The level check plug only needs to come out once its cooled off and you then set the level in the 95-113F temp range.  Leave it in for the initial temp warm up.  Do not remove it with the engine off as it will drain quite a bit of fluid out.    

 

 

On 12/21/2024 at 9:21 AM, mikeyk101 said:

Question, I know this is the procedure for transmission fluid check for the 90⁰ C thermostat bypass valve. Let's say you have installed the updated 70⁰ C (158⁰ F) valve or even did the pill flip, how would the instructions be changed or modified to account for this?

 

 

The procedure and temps above are for the 8 speed 2015-2018.

 

6 speed 2014-2018 and 2019 LD has a cold check and a hot check, the hot check being the preferred check.  Both apply regardless of what you've done to the TBV (stock, updated or pill flip/surecool).  Cold check should be done 80-90F transmission temp.  Hot check is 160-200F.  

 

 

  

Edited December 22, 2024 by newdude

[dakotadodge80]

I removed the fluid and filled it back up and trying to get the trans temp over 195 but it’s taking FOREVER! I know driving it will heat it up faster but isn’t that risky having not checked the level? It’s been running idle for at least 30 min now and still have a ways to go. 

[mikeyk101]

What you can do is while motor running, have it in "D", foot on brake, and slightly press and hold accelerator a bit. You obviously shouldn't do it for 20-30 minutes but a few minutes should be enough. 

[dakotadodge80]

Thanks! That’s definitely moving it along faster. (Ugh. What a PITA this is...)

[brent ward]

Having the shudder problem. Took to get filter and flush. still shudders. I noticed the synthetic fluid they replaced is NOT the Mobil 1 LV HP ATF blue label. My truck has a fill tube. Can I pump out of fill tube and replace with fill tube and do this 2 or 3 times to get a flush?