I've put 3000 miles on my motorhome with its "new" 1st gen Cummins and it runs really good. At the outset I've noticed a few small leaks (engine, power steering, etc.) but postponed addressing them so I could first address drivetrain performance issues.

So now i'm looking at the engine oil leak and I can see oil coming from two places (feeling/looking from under the vehicle):
1) down below - passenger side surface of the gear cover toward the bottom, and
2) Up high - passenger side top ledge of the gear cover (I can only feel the oil with my fingers).
.

It looks like the oil coming from above is oozing down into what I see down below. Of course, it's annoying as the oil ends up at the oil pan and drips on the floor/ground.

Anyway, prior to swapping the engine, I did R&R the crank front seal, religiously following the instructions, using a Cummins seal kit and Felpro gasket instead of RTV.

Other than a possible front seal leak, what other sources of leak from high up in front of the engine?

 

Oil cooler?

 

Not sure with out looking at it. But if you want I have tons of oil traced dye. If you need some pm me and we could meet up some where.

 

There's no oil seepage around the oil filter/cooler.

 

There are a couple of possibilities I can think of. One is the front timing cover to block gasket has shifted and is now leaking, I've seen it on a few occasions. I clean the area and smear some RTV in the corner where it meets and it usually stops the leak.

The other place up high is possibly the head gasket on the front driver side, I've only seen this once and it was on my own truck that was turned up.

 

High possibility, yes, oil leak also runs down the corner where the block and the aluminum timing cover meet at the left side of the engine.

As far as the front driver side head gasket is concerned, it is completely dry on the driver-side of the entire engine, from what I can tell from under the vehicle;

I will be able to confirm when i take down the entire front accessories (fan, radiator, belt, intercooler, condenser, oil coolers, etc..) :-( sigh

 

The culprit are 4 loose bolts of the gear cover, below and above the engine speed sensor - the exact location where i suspected. I must have been distracted when i was fiddling with the sensor gap 10k miles ago.

 

So you snugged up those 4 bolts and your back in buisness? Gotts love those easy fixes.

 

Indeed. I took the bolts out of their holes and cleaned them and coated the threads with rtv for good measure before i tightened them to 18 ft-lbs.

I still have not put things together as i will be replacing the belt tensioner assembly to solve the cricket/squeak noise when the engine is cold.

 

My cricket departed when I replaced the serpentine belt. I've since found debris in the grooves of my crank and alternator pulleys which may have contributed some noise.

 

The tensioner for sure makes the chirp when i rock it. Im replacing the belt too for good measure and will use the old one as my spare. I hope the cricket will forever be gone.