06 Cat C-15 coolant leak

You have 2 coolant hoses going to the pre-cooler, 1 is very hard to get at. That are both above the oil cooler. Goes from the pre-cooler to the oil cooler (the easy to change one). The other is goes behind the cooler to the water pump manifold. You have have a short hose from the water pump to the thermostat housing that's tough to see the whole thing on an Acert.

If it seals up when it warms up, it could just be a cold water leak, meaning tighten the clamps.

 

Cold leak. Big o-ring in the front of the oil cooler would be my guess. Fairly common problem. Mine is leaking a tad too if I leave it sit in the cold. Plugged in or apu running which also powers the block heater keeps it warm enough it doesn't leak. I'm replacing mine when it's in the shop this week for an overhead tho.

 

Yup, I have a C15 here that just started the same leak. As stated, it's a cold water leak, and a cash cow for dealerships as pretty much all of them do it. Since the leak is hidden and so much stuff has to come off to get to it, a lot of extra bits get replaced.

 

we have a 2004 accert likes water pumps for some reson

 

I know this is an old thread but anyway I've got a cold weather leak that popped up on my MBN recently that seems to be coming from the freeze plug in front of the oil filter just below the oil cooler. When the ambient temp is around 25* or lower it drips. Anyone ever seen that before? I'm pretty sure it's coming from the freeze plug (pic below) and not the oil cooler. Can I just knock the old freeze plug out with a punch and then use a socket/hammer on top of a new one to seat it in?

 

You can get the plug, but it is oil it is sealing not coolant. I would guess it is the bonnet o-ring.

 

Well this is coolant leaking and so from the diagram # 22 is where the leaky o-ring is running down and dripping onto that freeze plug? Right now it's not leaking. I suppose being based and mainly running in the southeast I could probably wait until next winter to get on this?

 

I wouldn't put it off that long. Leaks like that seem to bite you hard @the worse times.