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3.0 Duramax DEF Leak?

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Olympus Enthusiast

Olympus

Posted
Posted

I just went to refill my DEF fluid for the first time.  I slightly overfilled it with on a dribble coming over the fill cap.  I wiped everything up from the truck and garage floor and went back in the house.  I came back out to the garage a few hours later and there was a huge puddle of half-dried DEF fluid on the garage floor on the OPPOSITE side of the truck, passenger side between the bed and the cab of the truck.  I looked underneath and saw dried DEF on the side and bottom of the frame.  I have no idea how it leaked so much and how it leaked from the complete opposite side of the truck from where I filled it.  I checked the floor and it did not run from the driver's side.  The floor and the driver's side was dry and fine.  It's like it leaked from somewhere above the passenger frame rail and ran down.  Surely that's not normal, right?

Sqrls Enthusiast

Sqrls

Posted
Posted

You are not supposed to overfill it. The manual specifies this. I do not know if overfilling it will actually cause any damage. I have filled mine just like you describe, but it was right before a 500 mile trip. Maybe there is a purge valve as I’m sure the lines leading to the def injector have fluid in them that can try to leak back into the tank. 

steve841 Enthusiast

steve841

Posted
Posted
On 11/6/2020 at 5:30 PM, Sqrls said:

You are not supposed to overfill it. The manual specifies this. I do not know if overfilling it will actually cause any damage. I have filled mine just like you describe, but it was right before a 500 mile trip. Maybe there is a purge valve as I’m sure the lines leading to the def injector have fluid in them that can try to leak back into the tank. 

LMAO

 

how are you not going to overfill it?   There’s no indicator or sound when it’s near full and my crystal ball has been useless lately.

Sqrls Enthusiast

Sqrls

Posted
Posted

When fluid reaches the top of the DEF fill pipe, stop filling. Do not top off the DEF tank. If using a bottle or
 jug to refill DEF, follow the instructions on the container label and use a dedicated fill aid.

 

That’s from the diesel supplement manual. 

Olympus Enthusiast

Olympus

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  • Author
Posted
When fluid reaches the top of the DEF fill pipe, stop filling. Do not top off the DEF tank. If using a bottle or
 jug to refill DEF, follow the instructions on the container label and use a dedicated fill aid.
 
That’s from the diesel supplement manual. 

But you can’t see the top of the fill pipe when you have a jug with a nozzle inside filling it! I read that too and that’s the stupidest thing I’ve ever heard. That’s why gas pumps have automatic shut offs. It’s impossible to know when you’re full.
  • 2 years later...
TNDuramax3.0L New Member

TNDuramax3.0L

Posted
Posted

Filled up my new 2023 Silverado 3.0L with DEF for the first time after DIC said I had about 900 miles left. Per owners manual, supposed to fill it up until you see it come to the top of the fill port. While filling, started to hear fluid leaking on the floor on opposite side of truck, looked underneath, all kinds of DEF flowing out on the floor, it never came to the top of the fill port. My friend has the same truck, this has never happened to him. I also drive a 2018 HD2500 with the larger Duramax, you fill the DEF in the engine compartment port, never had any issues with that truck earlier. Will be seeing the dealer on Monday, not impressed with initial call to the service advisor, they told me if it stopped leaking it should be fine.

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