The only failures that WE have seen with Bosch rebuilt are when the fuel system is contaminated already! Bosch uses new "tips" the actual nozzle on all of the rebuilds.
IN the 80's when MB was selling over 60% diesel cars we were allowed to rebuild these nozzles under warranty, & they didn't last 20,000 miles.
MOST of these problems are due to POOR quality fuel!! over; dirt & water.
On many cars we had to install water separators in the fuel system so that the injectors would last at least 50,000mi.
ASK yourself WHY did the first injectors fail causing you to replace them in the first place???
Have seen many diesel motors with 300,000 and original INJECTORS!
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)