I have no idea what a part washer is, but maybe consider using an ultrasonic cleaner.
You can then either load it with surfactants (e.g. SLS) in a water phase or with apolar solvents like cineol, terpentine or limonene, which have similar solving capabilities as diesel, but are bio based and not as flammable.
Using surfactants alone without ultrasound won't work, but using solvents alone won't keep the particles in phase, as they would just sink to the bottom.
If you tell me exactly how this washer looks like/ works and what exactly you wanna clean, I can help you more.