george7941

The bottom of my 1999 24v Cummins always has some oil on it. The front crank seal was leaking badly, so I replaced it and about 90% of the oil leak is gone but there still seems to be a bit of oil coming out and I will have to live with it. The crank wasn't scored where the seal rides and I installed the seal dry as per Cummins instructions so I don't think I did anything wrong. I took out the gearcase cover to replace the seal.The Haynes manual says that you can replace the seal with the cover in place, I don't think it is really practical since it is really difficult to drive the seal into place from the front and if one side goes in too far there is no way to pull it back out. The seal goes in easier driven in from the inside of the case. I did it with the rad and the fan shroud in place. Are leaky front crank seals a common problem with the 24 valvers? After I replaced the crank seal I noticed a small leak from the power steering mount, so I replaced the gasket there and that eliminated that oil leak. I would like to have a oil tight engine, it looks like I am not going to have it with the Cummins. My oil cooler also seems to be leaking a bit, enough to keep its outside moist with oil. I tightened the bolts on the oil cooler. I currently have 160,000 miles on the truck. We have a Mercedes 906 engine in a Freightliner truck at work. It is a 6.4l inline six, so it is comparable to the Cummins, and it is totally dry at the bottom. Admittedly it is a much newer engine being a 2004 with only 40000mi. And no, the oil on the Cummins is not from the draft tube. I used a large socket to drive the seal in, I don't think it damaged the seal in any way.

Geico266

Cummins don't leak oil, they are marking their territory.

Mine has never leaked a drop. I do get some blowing out of the vent tube, but only if I over fill it.

yarddog

Mine only leaks out of the vent tube but it was designed to do that.