jtfcons wrote:
A couple of thoughts.
I would put a catch pan under the drip area and try to determine whether this is motor oil or diesel oil. If motor oil, the following is a possibility.
The 8.3C mechanical engine has an injector pump driven via a chain drive (possibly gear) at the rear right corner of the engine. The housing enclosing the drive has a gasket that mates with the engine block at the rear of the housing. This gasket is a known to leak a small amount of engine oil when it ages, hardens, etc. This leak would show up at the mounting flange area of the pump and could be viewed from below depending on the amount of junk in the way. There might also be some oil visible at the top rear of the engine along the line where the head and block meet. In my case, this leak never seems to make it to the ground, at least I have not observed any accumulated oil. Replacing the gasket is a pain requiring removal of the pump, etc. $$$$, therefore I live with it.
About 7 years ago I paid Cummins West $220 for a diagnosis to repair this leak. Their estimate was north of $2,350 plus the $220 or $2,570.
I fixed the Gear Cover Leak based upon the following post by a member of RV.net.
The fix was a small spray can of Permatex Form-A-Seal Leak Repair - NAPA #765-2650 @ about $5.00. I sprayed the area (couldn't even see the leak behind the pump) with brake clean several times (soaked it real good) and then applied the Leak Repair exactly as the directions said by letting it run down the crack from above the leaking area (actually used a watch to make sure the timing was perfect).
This has continued to be a successful repair.
