DD15 pushing coolant out overflow

[tsolson]

Hi,

I know this is a Cummins forum but....

I have a 2011 Freightliner, with a DD15, was demandated by reputable person from this forum a couple years ago. It's at 1.3 mil km, so mileage is getting higher for sure

It just started pushing a bit of coolant out the overflow on the surge tank. It doesn't use any oil, doesn't seem to smoke white, and runs good as far as I can tell. I'm wondering where to start checking for the source of the pressure. Could the EGR cooler be the culprit? There's no sign of oil in the coolant, and i don't see any coolant in the oil. If its the head gasket, I don't know if its worth changing it without doing an inframe? Its not cheap, rough estimate was 32K. I don't know what just the head gasket would cost, but probly in the 5-6K range.

I had the rod and mains done not long ago, and installed new oil pump and suction manifold, because of the famous hardened oil pickup tube o-rings.

Are these things even worth rebuilding?

thanks for the advice and opinions. I appreciate the amount of knowledge available here.