hd66: I have found NO info on this filter on internet. Only mention of it is in Operators Manual under 2000 hr maintenance. (Section 7-45?) No mention of what it is or what it does...... it is located on the lower right on back of engine, on what I believe is timing gear cover. There is a "picture" of the cover to be removed in op manual. You need to remove turbo air cooler & hoses above radiator, the radiator & hoses, fan shield, and fan blades to get to it. (3) 10 mm nuts holding on cover. I did not remove attached hoses on cover, it pushes out of way pretty well. I took mine out this morning, (wasn't too bad a job getting to it other than all the oil all over everything from it spitting it out dipstick!), Filter is held in place by a decent sized snap ring on a spindle. Had to invest in a heavier duty snap pliers. Hope to get the snap ring reinstalled tomorrow, and start putting the radiators back on. Going to wash and flush out everything with solvent to try to get the oil out of air system.
Filter I took out is obviously part of the oil system, as it looks like an old dirty oil filter after a period of time. It does not look "plugged", Element seems to be a polyester fiber. Is not very big, coffee cup diameter, maybe 1.5 in. thick.
If I get it replaced and back together, going to run it up to temp incrementally, checking oil and coolant regularly, before working it hard.
If this does not work, it has been suggested that I try a motor flush cleaning treatment by Amsoil, Cenpeco, or the like. Might consider doing it anyway, as obviously something is gumming up the system, and needs to get out. Why they put this "blowby filter" in such an inaccessible area to check and service is a mystery......
Will let you know if this works. Good luck on yours. Thanks for starting this thread.