Oil Leak front end

jyragui

New member
Nov 13, 2025
9
5
3
Kenai, Alaska
Hello, I recently purchased an older 01' 2500 hd LB7. Everything ran fine until last week when I went to install some nerf bars, i noticed a large amount of engine oil leaking from the front end of the truck. I popped the hood and there was oil spray covering the front of the engine. I got it into a shop, pressure washed the engine clean and ran the truck for ~ an hour. No leaks. As soon as I drive it home and pop the hood there is oil spray everywhere again. It wont leak until i'm driving down the road. The fan blade is picking it up from somewhere and spraying it. I just replaced the 2 PCV's hoping that they were faulty and causing an over pressure scenario, does not seem to be the case. Any other ideas for me to try? Thanks for your time.
 

mojito5000

Member
Aug 20, 2019
51
5
8
Oregon
What color is the oil? If it happens only when driving could be a fitting on the trans cooler (or the cooler it's self) is leaking.
 

jyragui

New member
Nov 13, 2025
9
5
3
Kenai, Alaska
Its dirty by the time i find it. Blackish/dark even though the oil was just changed under 1k miles ago. Yes it only leaks when its driving down the road. I've ran it for hours in the driveway reving it up etc... to try and find the source and it cant find a drop.
 

mojito5000

Member
Aug 20, 2019
51
5
8
Oregon
Grab a paper towel from the kitchen and wipe some of it. That will typically show any colors.
Could also be power steering, which would be clear, but could be dark if the dirt and muck from the engine contaminated it on it's travel down.

These engines are pretty tight. I've had leaks from everything other than engine oil.
 

jyragui

New member
Nov 13, 2025
9
5
3
Kenai, Alaska
Found it. Not sure why after looking for a week i find it as soon as i post here but thats the way it worked. Its coming from the oil fill tube. Is there supposed to be some sort of rubber seal where i'm pointing or is it just mechanical? I forced the throttle open to about 2k rpms and saw it coming from there pretty forcibly. Straight clean engine oil pooling up. thats the oil fill tube.
 

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TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
16,919
3,422
113
Mid Michigan
Yep, should be an oring there. Always fun buying someone else's unfinished work.