if you have a good welder weld it **** it should be air tight. yes some coolant will get into it but if you actually sit down and think about it its going to take a long time for that cooler to fill up with coolant. and you would have to have that truck running for a long *** time for that radiant heat to heat up that coolant to a boiling point.

welding it is a safer way of doing it due to that fact that there is a bellows on that up pipe and that inlet was placed in that spot for a reason. it was also a brace for that up pipe, now you take that brace away and now every time you accelerate your motor shifts. not as its shifting that pipe is bedning back and fourth. once it bends back and fourth a lot that pipes life is over. now you got a major exhaust leak.

just my 2 cents

 

If its welded shut it shouldn't fill up with coolant unless you have a pinhole or a crack. There is no way it would get hot enough to manipulate that weld and if it ever did I wouldn't be close enough to that truck to find out. Clean it good with some acetone or burn everything off with a torch.

 

The internals of the EGR cooler can still fail (though there's no hot exhaust gasses going through it now). That's where the coolant would come from and it wouldn't take a long time at all, but once it's filled with coolant... so what it can't go anywhere else.

All of those exhaust components you're referring to are hard mounted to the engine, so if the engine is moving, those pieces are moving with it. There is a flex section in there to ensure you can connect all of the hard pieces and get them sealed properly. Same idea as putting a gasket in between the block and heads, need something to take up for misalignment and imperfections. Removing the cooler does indeed leave the up-pipe flexing in the breeze so to speak though, so it is wise to use a solid up-pipe if the cooler is removed.

It can be welded and still fill with coolant... the welding of plates on the end is only sealing off the exhaust from traveling through there. Coolant is still flowing through it like normal and it can still crack inside the EGR cooler. Especially if your oil cooler is clogging. It's less likely, as the hot exhaust is no longer going through, but don't think it can't still fail. Again, if it does, it just fills with coolant inside the cooler and can't really go anywhere harmful.