With what's stated before, I wouldn't pour any liquid that's petroleum based into the intake or engine of a diesel..seafoam or not...or else your going to have a major issues like the guy who did it with the seafom in his dmax. Other then a smoke machine or building a leak tester (since you don't have a compressor at access), good-ole soapy water and spray bottle and spray around the couplers, turbo, charge pipes, etc. and have someone rev it and see. And for exhaust leaks, check for black smoke marks on the fire wall or in the surrounding area.
I know you stated before your not going to use seafoam, but again I wouldnt put any type of liquid in to the engine...more than likely something is going to cause problems. There's yet of anything i've seen on the market that would be or is considered to be a viable source for a diesel engine.