'83 300 TD

I just purchased my first MB and it's an '83 TD. Overall it's in pretty decent shape, with just two minor problems; the rear is really bouncy and the steering wheel has some play in it. Before I even begin tinkering with my new driver, I want to pressure wash the engine bay since is has about 178K miles of grime and grit. Is there anything I should be carefull of when pressure washing the engine bay. This is my first time with a MB and a diesel and don't want to soak something that just isn't meant to be wet.