D8 36a Diesel in the oil

Good morning, getting diesel in the oil. Thought it was the drain tube on the lift pump because it was plugged. Unplugged the line and went to change the oil. I left the drain plug out overnight and noticed the next day diesel was still dripping 24hrs later. Removed the covers on the oil pan and diesel is dripping thru the oil pump. When i drained the oil there was a significant amount of diesel. Probably a few gallons. It leaks even when the engine is off. Has anyone had this issue before and where would the diesel enter the oil pump?

You need to change the 8B4967 fuel gallery seal. #9 in picture.

Great. Thank you! Is this fairly common on older Caterpillars?

Yes, common to units that have the integral fuel passage between housings. Later units had external connections that would not result in internal leakage.

I don't have experience with the D8 or larger machines but on the D2 andD4 that I have worked on have the same o ring seal at the other end of the tube also. The one pictured is usually the one thats bad but its not a lot more work to replace both o rings since you're that far into it. It will look different from years of compression but is in fact an o ring.

Only one seal used on these D8's 8B4967 = trade size dash 318.