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2025 3500 cummins zf8 oil leak

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woodrow

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I found this oil residue under my 25 ram cummins when changing my oil. It has 8k miles on it, has anyone else had this issue
 

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Wipe it off, and keep an eye on it. None of my vehicles ever did that. But, not to throw you into a paranoid episode, I have seen leaky rear main seals do that, as well as leaky transmissions. Use a white paper towel, wipe the fluid up, give it a look and a sniff, to see is it is engine oil or transmission fluid.
 
I had the same thing today.
It was green oily fluid on the floor.
25 Dually with ZF and 10000 miles.
Are we sure it's this CATS thing that's described above?
 
I just found out today, it was my rear main seal leaking.
 
Service department ordered the seal Friday and said they should recieve it tomorrow, install will take a day
 
My 2026 also showed oil. It was a drip on the bottom of the cover and moisture like yours. But, no oil dripping on the floor. I wiped it all clean and have not had any show of new oil.
I would not let the dealer replace that seal just yet. I question how the mechanic can tell the difference between assembly lube leakage and engine oil leakage.
Replacing the rear engine seal requires a minimum of removing the oil pan and most likely removing the transmission and oil pan.
Just clean it up and see if it returns. Mechanics, even good ones, can make things worse.
An engine rear main seal leak is going to be dripping on your garage floor. If it is not leaking onto the floor no seal needs to be replaced.
 
That's what I was thinking the last thing I want to do is have a dealership pull a tranny to just to replace the main seal. I feel like that's going to cause five times more problems later on. I'll have to trade the truck before I let that happen.
 
slideandride said:
That's what I was thinking the last thing I want to do is have a dealership pull a tranny to just to replace the main seal. I feel like that's going to cause five times more problems later on. I'll have to trade the truck before I let that happen.
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Removing and reinstalling a trans is stupid simple and not really much to screw up and cause other issues…. You sound a bit ridiculous with that statement.
 
H3LZSN1P3R said:
Removing and reinstalling a trans is stupid simple and not really much to screw up and cause other issues…. You sound a bit ridiculous with that statement.
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First half of your statement is true, second half not so...... Definitely not to say all mechanics will screw-up, but many can/do.
Case in point, how many new diesels go out the door with the engine heater cord disconnected, even with a RAM TSB stating not to do that. And, I can quote many more serious examples.
 
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I didn't wipe it with a rag, thats not normal to have that oil film. They also told me they replaced a flange. The service guy didn't know to much what he was talking about. I asked him to make sure I had the latest flash on my tcm and he was clueless. I pick the truck up tomorrow evening and will post what was all replaced.
 
Thanks for the follow up. Let’s hope that problem is behind you.


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