CM2350 Oil Cooler Leaking

[JimT]

So, having recently replaced my oil cooler I can say that oil wouldn't be leaking out around the outside of the cooler housing. Those bolts secure the housing into a coolant channel on the block. So torquing them down won't fix an oil leak. If it's coolant then maybe. The front of the cooler could be leaking where the thermostat sits. That might need removal of the cooler housing or the AC/alternator accessory bracket (any maybe water pump too). FYI, the EGR cooler sits over and uses 4 of the same studs as the oil cooler so you'd need to remove the EGR cooler to get the oil cooler out.

Before playing around with the oil cooler though, take a good hard look at the front of the engine. The gear cover tends to leaks at the top passenger side or you could be leaking oil from the valve cover or the head from the front or front/passenger corner. Also could be leaking from between the head and gear box. In these cases it's possible and likely that the oil would travel down and find it's way to where you see it.

Agreed that the first step should be to clean that entire area off really well. Also inspect and clean the front of the head and gear box. Take a really good look at the top passenger side of the gear cover and look down around the area where the 2 head bolts are at the front of the head. (I spilled some oil there when reassembling after my inframe and the oil made its way down to the thermostat and front of oil cooler).

Then, if you don't find anything new, run the engine looking for leaks, probably drive it around a bit and keep watching. It really doesn't take much oil to cause a wet spot like you have there.