Ford's answers to the NHTSA 6.7 Investigation
There was a request for a link to Ford's answer's to the NHTSA investigation posted on a previous thread, since closed. Here is the link: Ford's NHTSA Answers to the 6.7 investigation This PDF i...
Forum Discussion
Some other thoughts.
It has been discussed before, but it's worth repeating. Bosch claims that their cam roller / follower is self aligning due to spring tension. That may be true under static conditions, it may not be true under dynamic conditions. Anyone that has watched what springs can do to a valve train under a rocker arm can see the dynamics of the spring causing the valve, via a rocker arm, to rotate, at various rpms, due to spring construction variances, harmonics, oscilllation frequencies, what ever. This design has no alignment mechanism designin place to keep the cam roller in alignment and squared up with the cam surface in dynamic conditions. The piston is free to rotate in the bore, taking with it, the cam roller follower.
The question begats an answer as to what is causing the piston to rotate in the bore? Is it fluid dynamics and vortices inside the pump, due to the location of inlet or outlet valves? Could they at higher flows, higher rpms, or under cavitational conditions cause the roller and piston to rotate? Where on the cam and roller is the cavitation taking place? Is the pressure differential creating a temporary sucking motion too, to draw the roller in at the side, instead of equally across the cam surface? A lot of diesel fluid goes through this pump lubricating it and keeping it cool. My fly fishing experiences on a river is what had me thinking this, how hard it is to present a fly, with complex velocity changes in eddies and flow on a river.
Just some more things that make you go "Hmmmm?"
It has been discussed before, but it's worth repeating. Bosch claims that their cam roller / follower is self aligning due to spring tension. That may be true under static conditions, it may not be true under dynamic conditions. Anyone that has watched what springs can do to a valve train under a rocker arm can see the dynamics of the spring causing the valve, via a rocker arm, to rotate, at various rpms, due to spring construction variances, harmonics, oscilllation frequencies, what ever. This design has no alignment mechanism designin place to keep the cam roller in alignment and squared up with the cam surface in dynamic conditions. The piston is free to rotate in the bore, taking with it, the cam roller follower.
The question begats an answer as to what is causing the piston to rotate in the bore? Is it fluid dynamics and vortices inside the pump, due to the location of inlet or outlet valves? Could they at higher flows, higher rpms, or under cavitational conditions cause the roller and piston to rotate? Where on the cam and roller is the cavitation taking place? Is the pressure differential creating a temporary sucking motion too, to draw the roller in at the side, instead of equally across the cam surface? A lot of diesel fluid goes through this pump lubricating it and keeping it cool. My fly fishing experiences on a river is what had me thinking this, how hard it is to present a fly, with complex velocity changes in eddies and flow on a river.
Just some more things that make you go "Hmmmm?"
