How often is everyone blasting the carbon build out of the engine via the infamous "Italian tune up." Before I blocked the egr I used to run in 3rd gear at 60-65mph (70 is top speed for 3rd in an 83 300sd) for about ten minutes, every 1,500 miles. It made a huge difference. There was a good deal of carbon buildup; as the coolant temp. rose to 100c I would occasionaly see a quick belch of black smoke. Imediately following the blow out's my engine was transformed. Since blocking the egr, 10,000 miles ago, I haven't noticed any sort of performance deterioration (ie. carbon build-up). So I'm wondering; Do you guys think it's still necessary to perform an "Italian tune up" on an egr blocked diesel?

I would say yes. A MB diesel engine frequently driven at high rpms does better than those that don't, with or without EGR.
-Joe

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

What Joe said. If you putter around town or in traffic, you'll build up soot that an Italian tune-up will clear. If you frequently drive with the engine over 3000 rpm for extended periods there's less need for/benefit from Italian tune-ups.

Sixto
95 S420
87 300SDL

Just go find a nice long hill and keep it in the power band...let it get nice and hot
Around here, hills come with curves so it puts the whole car into a full body workout

wols0003,

But an Italian tune up does not clean out the main problem caused by EGR. That is the crap buildup in the intake manifold. The intake manifold can only be cleaned by removing it from the engine and manual or hot tank cleaning.

P E H