Old-style injector nozzles seem superior

[DieselAddict]

I recently did an experiment with the injectors in my 87 300D. I had been battling a significant combustion knock at idle for over a year and just about trying everything. The only thing that temporarily killed my knock was bringing the car down to a lower elevation (over here I'm at 4500-5000 ft) or running the car on Diesel Purge. Twice I inspected and balanced my injectors to no avail.

Recently I was also rebuilding the injectors in my two W123 diesels and I noticed the nozzles used in those engines are different from the ones used in the OM60x engines. The OM616/617 engines use Bosch 240/ nozzles that have a crosshole on the side of the tip of the pintle and an exit hole on the tip of the pintle. The OM602/603 engines use Bosch 265 nozzles whose pintles have no holes and they just have a longer tip. From my testing I found the 240/ nozzles produce a very fine spray while the 265 nozzles spray more like a garden hose with a thumb placed over the opening and I tested both used and new 265 nozzles. So I decided to use the 240/ nozzles even though they are not the right part for this vehicle, but I'm quite pleased with how the car runs now. The combustion noise at idle has been noticably subdued and it's a lot more steady and consistent. The car has about the same acceleration as before. The only possible downside that I noticed is that during deceleration just before the engine reaches idle speed the diesel clattering now comes and goes but I think I'm hearing it less as I drive the car more and it's possible it was caused by carbon buildup which may be getting cleaned out.

My question is, why did MB or Bosch get rid of the crossholes while designing the 265 nozzles? IMO they are essential for producing that fine spray that the 240/ nozzles have.