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Transmission Dipstick...?


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First off, I come from the Duramax world.  Simple check of the Allison along with fluid replacement regularly never bothered me.

  Ok so I have a 2021 6.6L L8T 3500DRW.  Popped the hood to fill up washer fluid decided to check the oil.  Was looking at all the space under the hood compared to my LBZ or my  now sold LML and noticed there is no trams dipstjick.  Wtf?  Or am I just blind?  Please tell me I'm blind.  How do I check and replace amd refill the rrans fluid in this truck?

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Many, maybe most cars and trucks with auto trans no longer have dipsticks.  The trans are basically sealed and require no fluid checks.  Ford and GM truck transmissions are sealed as well as most of the car transmissions.  Fluid levels can be checked but you have to get the truck high enough into the air to get under it and check it from below.  There is no need to check as long as there are no leaks.  Corvette transmissions have been this way since 1997 so it's not something new.

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I remember this being something from years passed.  Like getting under it and checking with the tip of your finger by feel because your couldn't stick your heads up there especially while physically checking it.  I'm not sold on this for Trucks, especially HD trucks meant for hard work like mine and many others or possibly even sport model cars.  Did they do this to the Duramax trucks too?

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Anyone? 

 

....Or is it a dealer secret that even the mechanics don't know, so they just tell them to replace the entire transmission anytime there is a reason to suspect degraded fluid somehow?

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If you go by the owners manual you should take it into the dealer to change the fluid or reference the service manual. Only problem I see is that I can't seem to find a service manual for a 2020 or 2021 model years.

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No dipstick.

 

Fluid level is checked via a level plug that is in the pan.  DO NOT remove the plug is the truck is OFF, you will drain fluid out.  

 

These transmissions are not "sealed for life".  They are serviceable.  Draining, filling and level check is all done from underneath.  Plug # 1 can be used to fill, plug #2 is the level check plug but can be used at the dealer as a fill port as well.  You can also use it to drain "some" of the pan.

 

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Edited by newdude
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Level check procedure.  Again, done engine ON and within a specified temperature range:

 

 
Quote

 

Transmission Fluid Level and Condition Check

This procedure checks both the transmission fluid level, as well as the condition of the fluid itself. Since the transmission on this vehicle is not equipped with a fill tube and dipstick, a tube in the bottom pan is used to set the fluid level.

More information, including an instructional video, can be found at the GM training website: Center of Learning: 17041.62V - 6-Speed Automatic Transmission Fluid Checking and Filling Procedures.

 

Caution: The transmission fluid level must be checked when the transmission fluid temperature (TFT) is between 30–50°C (86–122°F). If the TFT is not within this range, operate the vehicle or allow the fluid to cool as required. Setting the fluid level with a TFT outside this range will result in either an under or over-filled transmission. TFT>50°C=under-filled, TFT<30°C=over-filled. An under-filled transmission will cause premature component wear or damage. An over-filled transmission will cause fluid to discharge out the vent tube, fluid foaming, or pump cavitation.

 

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 trans 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. Replace the transmission oil level check plug and tighten.
    • M6 oil level check plug 9 Y (80 lb in)
    • M12 oil level check plug 25 Y (18 lb ft)
  9. Inspect for external leaks, refer to Fluid Leak Diagnosis.
  10. Reset the oil life monitor only if the fluid was changed.

 

 

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Thanks for the info newdude :thumbs:. Pretty knowledgeable stuff for a new guy😜.  Good info to have for future recollection, much appreciated

 

I can tell already. I have a lot to learn on these new trucks(and gas jobs in general as well)

Edited by THE YETI
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On 8/5/2021 at 4:15 PM, newdude said:

Level check procedure.  Again, done engine ON and within a specified temperature range:

 

 

 

Is there a way I can subscribe to wherever you got this information from?  Im sure it has any and all information I may ever need when working on this truck (or others) in the future

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He works for a Dealership, so he has everything.

 

You can subscribe to a service like Alldata.

 

Alldata has $60 for a year and $120 for 3 years. This is USD money I am talking here.

 

 

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  • 2 weeks later...

Having no dipstick is great   Until it isn't!   They discovered a few drips of transmission fluid under the truck   Thought it was probably the transfer case seal (requires pulling the tranny)  But lo and behold it is more serious than this.  Waiting for some new tranny parts and maybe a week before I have my truck back.   Would have been nice to have been able to check the fluid as I'm pretty sure this would have discovered the problem before it became more serious.    Covered under warranty now but what about in 6 years?

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