So I just got back from town in the 300D and I opened the door when I pulled in the driveway while it was still running and it sounded like I had an exhaust leak so I popped the hood and the sound was coming from the #3 injector. There is compression coming out around the middle part of the injector. I want to get a little insight before I dig into it.

The copper seal at the bottom of the injector will need replacing. If it has been leaking for some time it can be difficult to get the injector out with the carbon build up. When the injector is out it all needs to be cleaned and sometimes the seat in the head re-cut if damaged.

dont forget to heat up the cooper shim before mounting , it will hold much more