is normal for 602 and 603 engines. it is generally agreed it comes from the egr. many disable it. also most folks seem to think that synthetic oil helps avoid the tar buildup.

clean it, out disable the egr, and live happily ever after.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.