When tearing down my son's engine for rebuilding, we suspected that perhaps it wasn't just a head gasket that led to all the gunk inside the engine, since there was so much of it around the oil cooler area. So we decided to bubble-leak pressure test it for peace of mind. Luckily it tested fine. A new oil cooler is north of $700 = Crazy!
I couldn't find any other threads about how to go about doing this, so here's how we did it. Made a couple of blockoff plates out of some flat steel that were rtv siliconed in place. One I tapped and threaded a HVAC Schrader valve onto. This I hooked up to my air compressor, since I found my nitrogen tank to be totally empty, but in this case pressure is pressure. I tested it up to 75 psi, figured that was enough.
I couldn't find any other threads about how to go about doing this, so here's how we did it. Made a couple of blockoff plates out of some flat steel that were rtv siliconed in place. One I tapped and threaded a HVAC Schrader valve onto. This I hooked up to my air compressor, since I found my nitrogen tank to be totally empty, but in this case pressure is pressure. I tested it up to 75 psi, figured that was enough.