I think MB designed and installed the trap oxidizer mainly as a stop-gap measure so they could continue selling diesels in California in 85-87. It was known to require extra maintenance and was also known to probably not be a final solution to excessive soot generation with the the current diesel designs -- probably when the 603 isn't in current production as there isn't anything seriously bad about the design. The newer CDI/TDI engines make less soot and more power.

When the trap goes bad, it sends chunks of creamic material through the turbo, killing it. MB always planned on replacing the system if it failed, since California requires lifetime emissions control, so when the catalyst was worked out, they changed over. There is a performance boost as well, and there is no restriction on the use of additives. The catalyst will not harm the turbo. Replacing it with a straight pipe will do essentially nothing for performance, and will void the warrenty on the turbo, it any.

The head design problems have been solved, but the aluminum head will still crack if severely overheated. One is well advised to use only MB orange coolant and to keep an eye in the upper radiator tank nipple, expecially on Behr rads - it gets brittle, particularly if green coolant is used (the anti-corrosion compounds are different and affect the plastic). If the nipple breaks off at speed, you will fry the head pronto. Not good! You should also watch for oil in the coolant tank, indicating a leaking head gasket. Head gaskets will fail more frequently with the aluminum head than with a cast iron one -- roughy every 150,000 miles.

The bent rod problem is sporadic, if fatal to the engine. The 3 L suffers from bent rods, too, usually #1 or #6, but not like the 350. The rebuilds are fine -- the rods are about 3 or 4 oz heavier! Rebuild will require all new rods, sleeves, and new pistons -- about $5000 in parts. Used good condition engines are just about non-existant.

My advice is to keep the thing in tip-top shape, do the maintenance religiously, and don't worry.

Both of ours run like a dream, 174,000 on one (new head) and 130,000 on the other (had trap oxidizer changed last fall!)

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!