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Will a high pressure washer (1750 2 gpm) washer be effective in cleaning the engine and suspension on a fairly well gunked up 123? I was planning to spray soak with simple green, 409 or some other cleaner (recommendations??), let it soak in for a bit then wail away at it with the washer. Then do it all again about 2 or three times. Intent is to clean it up enough to make doing some needed work a little more pleasant.
Advise appreciated.

I'd stay away from the pressure washer- don't want to break a fuel line, fuel return line or damage your radiator.

Yes, stay away from that high pressure washer... only bad things can come from that...
Use more ' dissolving power' and less force....
I get a one gallon can of ' Gunk concentrate" and mix with about 6 gallons of kerosene.... then spray on and let soak overnight.... then I just use my thumb over the end of the hose to knock what I can off...
If more is left, let dry, ( doesn't take long in Central Texas ) and spray, let soak and spray off again...

I use simple green, purple stuff, power orange etc. (whatever is on sale at the time) on a cold engine with the car up on ramps spray everything on top and under and let soak for 20 minutes or so then hit it with a small electric pressure washer. I think it is rated at 1500 psi and I can fan the spray so it is not as strong in one spot. Works great and I avoid really blasting the fuse box and alternator. This has been the best way I have found to keep things clean and always do before I have to do any work that would normally be real dirty. The kerosene based cleaners stink and the whole car would smell like raw fuel for days after I used them. Also don't think they work as well as the heavy degreasers do.

You can probably guess that there's two camps on this. I suggest you try the search feature again and read all you can about washing engines. Then, search for threads from those who experience "all of a sudden" problems after washing engines. I think washing engines is a bad idea.

How about steam cleaning? I have an old steam jenny that I have never used to clean anything. I fired it up once. It puts out a bunch of steam. Any harm in cleaning an engine with steam?

One more thing to look out for when cleaning your engine is to be keep water away from the very rear of the engine/front top of the trans. There is a vent on the top of the trans and when rinsed water will run down the back there and can get into your transmission. On most of these old MB's the trans has sort of a channel that directs water into the vent cap. Water does not do any good inside the tranny either.

I prefer the "hose end" type of pressure washer with the small detergent resavoir. It gives me just enough pressure to clean things up without as much risk of damage to engine components and finishes with a rinse. I would be careful about using "harsh" chemicals on the engine. The wiring in the engine area of my car has brittle insulation in many areas, I feel was caused by this. If it is really dirty, more passes is a better idea.
However, I have been thinking of using your pressure washer idea on the undercarriage. I think as long as you used "distance" in that area, you would have a tough time damaging something.

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Sam

84 300SD 350K+ miles ( Blue Belle )