I am in the process of installing a used 6.2L diesel into my truck and after removing the air cleaner have found the intake plenum chamber and runners have a coating of what I call sludge on it and the air filter is extremely nasty suggesting possible poor maintenance by the preivous owner. Sludge is about 1/4" deep and I was wondering if this means it is excessively burning oil and the blow by is being sucked through the intake as I am new to diesel rebuilding/troubleshooting? I have also removed the oil pan and found it to be very clean with none of this sludge present in the lower end and pan. Any suggestions as I don't want to have to take this out shortly after I install it? :confused:

I am guessing that the engine you aquired had/has egr. Egr makes a mess out of the intake runners. At a bare min. you need to remove the intake, clean it very well, disable the egr or find a heavy duty non egr intake and clean the intake runner to the cyl heads.

I hope you removed the rear main rope seal and replaced it a Fel Pro 2 piece neoprene oil seal. With those miles on the engine then the seal should be leaking. I replaced our rope rope seal at 176K miles and only a one inch long fragment of it was left.

I am in the process of replacing the oil pump and rear main seal at the moment. Once I complete with that I will remove the intake, clean intake runners in heads, and replace the manifold with a clean J-series manifold I recently bought on eBay. Thanks for the advice, really appreciate you guys...