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Something is leaking

2K views 8 replies 5 participants last post by  lb7dirtymax01 
#1 ·
I have an 04 duramax with a plastic fuel tank, something is leaking down the fuel tank but it does not smell like diesel. It has turned into a good sized puddle under the truck. I don't want to pull the tank yet to find out what it could be. Anyone have any ideas?
 
#2 ·
The only thing that could be leaking down your tank is diesel, or possibly brake fluid. You may have a cracked or rusted out brake line. Im assuming its leaking out overnight while your truck is parked, so its probably diesel. Are you noticing lower mpgs? is your brake fluid getting low. Check all your fluids , top them off, and figure out whats coming out. Or maybe you got snow in your bed this past week and its melting haha.
 
#3 ·
I ended up getting a chance to look into it again after a lot of fluid had drained out of it today and checked the brake fluid... Turns out its the brake line popped right above the tank. What a great design Chevy did on designing that placing the line where water and snow will sit up there forever. It did throw me off how much was leaking after it had just sat there.
 
#5 ·
I'm glad to see you've pinpointed your problem. First off, whether your fixing it or having it fixed, brake fluid is EXTREMELY corrosive. Clean where it was leaking, especially painted surfaces, after one day of sitting on my old junker (powerstroke) I could remove the paint by rubbing it with my fingers. So be careful haha. Also that brake line may be easier to replace by removing the bed. (8 bolts underneath and a few wiring connectors.) Good luck!
 
#6 ·
bed removing ftw..so easy
 
#7 ·
I bought a 5-6 foot piece of brake line and two compression fittings to fix this problem on my truck. Apparently using compression fittings on brake lines will fail PA inspection if it is seen, but being between the bed and fuel tank they can't be seen and I have not had any problems with them for over a year.
 
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