EGR Cooler "Nightmare Nut" Removal

You can check @Mendel Leisk posts as he has links on how to do that job in the signature line of all his comments. His suggestion for that nightmare nut is to work on getting that one loose prior to the day of doing the job. I'm about to dive down into the Gen3 EGR rabbit hole and start doing them regularly and my plan is to have a clean EGR and cooler ready to go so I just swap them rather than having to soak and wait for them to be clean... Seems like that's the strategy of more than just me, lol...

 

As I recall, it is an external torx net, either an E8 or an E10.

External torx nuts are commonly used in German cars like BMW and Mercedes.

 

It's a run-of-the-mill hex nut.

The stud it goes on has an external Torx end, so that you also have a way of removing the stud.

 

You take the nut off first and then remove the threaded stud with an E8 external torx socket on a 1/4" drive. Pulling the orange cables out of the way is reported to help gain access.




The hex nut has to come off first. Recently one guy managed to break the stud off trying to use the torx socket without loosening the nut.

 

You could get the nut loose by a turn or two and then remove the stud with the nut still on it using the E8 bit.

You just shouldn't try turning the stud when the nut is jammed down tight.

 

I would leave both the nut and stud off, permanently. If selling or trading in the car, “maybe” reinstall. With them off, the cooler can be extracted without removing the two studs at exhaust manifold, which keeps the gasket there from falling, and makes alignment during reinstall dead simple. You do need to loosen the mounting bracket of a tube running above, channeling gas tank vapour back to intake manifold iirc. It slightly obstructs the cooler as you pull it forward.