where is the most common place for the mighty Cummins to spring a leak? I have some oil all over the bottom half of the engine. it doesn't drip though.

thanks!
Lance

 

There's a good chance that it could be blow-by from the vent tube. I would check to make sure that wasn't the culprit.

 

If the blowby tube isn't it, some of the 12 valves have been developing leaks in the line that runs to the vacuum pump. Check that out..

 

The front cover on mine has been leaking. It does not drip though. Plan on fixing that next week.

 

In addition to the locations already mentioned, check the gasket between the timing cover and block. Mine failed and it didn't drip just coated the suspension and oil pan after driving. Could not find the actual leak location at idle you had to run it up a little bit and watch closely because it was up high. The timing case was not damaged. Tech told me that the cover bolts had just worked loose slightly after 150k

 

What I did to keep the blowby from oil painting the bottom of my '95 is just slip a piece of 3/4'' ID hose over the stock one to extend the end a few inches from the ground. Paint the pavement not the truck. I didn't clamp the extension at all, figured if it ever got caught on anything it would pull off easily. Well it's been on there for eight years now...

 

It looks like it might be coming from between the head and the block, is that possible? it leaks out on the passenger side, toward the rear of the engine under the manifold.