cm2250 egr cooler leak need advice

[Rawze]

Assuming you live on a country where that stuff is legal, buy a new one, or weld shut the exhaust side of it (not the coolant passages),.. do not block coolant flow through it.

You could also just buy a new one and count the blessings that you have no more EGR issues (hopefully you have programming that has been verified/done by someone recommended on this forum so that your not trading dpf problems with repeating engine failure problems) ... It is rare that the OE cooler will leak (unless abused or installed incorrectly), that it is probably worth buying another just to keep the truck as stock as possible.