Several weeks back my 300sd had been running very poorly. This is after about 75-80K on a 2 tank WVO set up. It was idling rough and lacked power on the highway. It felt like a clogged filter so I changed both filters. It continued to run poorly. It was difficult to maitain 80mph. One day while leaving work I decided to try and clean it out. I filled the wiper resevoir with water, removed the hose connection from under the hood. I poped the top off the air cleaner and stuffed the hose down the intake. Most of the ride home I kept hitting the wiper/washer switch. You can feel the motor bog slightly(have to be careful not to hydrolock it with too much water). This was all done at highway speeds. When i got home the resevoir was empty. I replaced the hose etc.
I was very surprised to find that it now runs as good as ever. I really didnot expect such good results. If I didnot do this myself I would not believe it. I must caution though that I am at the point where I am considering replacing this car because of rust and age issues and really felt like I had nothing to lose. I don't think I would have attempted this on a better vehicle.

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81 300D Turbo 190K sold
83 300sd 319K best $500 I ever spent-daily driverw/ 2 tank WVO set up