* In the interest of locating your under-hood fluid leak sources, it would be very useful to pressure wash the engine compartment. From above and from below. The engine, both fender wells, oil hoses and cooler, everything you can get to. Diesels clean up very well, particularly if they've been leaking fluids, unchecked, for a while. When it's clean watch it very carefully over the next days or week of driving and you shouldn't have any trouble pinpointing all your leak sources. Without the cleanup, everything is coated with grime and appears to be leaking everywhere.
* Take a little care around the relatively few electrical switches, sensors and don't hit them with a direct hi-pressure spray.
* You can use degreaser if you want but I've never found it to be that necessary. The main thing is a good hi-pressure stream. Warm water is better.
* Aside from the pressure washer (much better than a car wash) I bought a cheap rain suit at KMart. Water boots and some safety-type goggles and you're ready to power wash. If you don't get the raingear, plan on not being able to clean anything you wear. It sounds like an involved operation, but it's not. The hardest thing can be finding a suitable place to do the cleanup.
* The repair time, effort, and effectiveness as well as the appearance, IMO, make the cleanup well worth the effort. Don't forget to put a little oil or grease in all the pivots that just got washed.

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ASE Master Tech
Quality Enterprises
Mercedes Svc. & Restoration
Sheridan, IN
317.769.3536