There are only two places I would use a torch on a Benz -- getting old bushing out of control arms (only enough heat to melt the rubber, a propane torch works fine) and on the bottom nut on a kingpin ONLY when the kingpin is being replaced. Never on anything else.

If you heat the control arm hot enough to get the ball joint out, it will be distorted and the new one won't stay in.....

There are a couple ways to get that ball joint out. A brass or aluminum drift and a 5 lb sledge has always worked for me, but if that doesn't, Harbor Freight sells a removal/installation tool. Get it set up to push the old one out, crank as much pressure as you dare on it (the "clamp" will bend, by the way....), THEN use the drift and 5 lb sledge to "start" the ball joint. If it still won't come out, replace the control arm, you will surely bend it otherwise, and the new ball joint is unlikely to stay put if the old one is that corroded.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!