BenK wrote:
Thought so, then ask what is the common ambient conditions for the failures
to date?
If they are all in same/similar, another nail on the lid
By elimination, I've or my view is that the issue is with this pump
alone. Whether tiny car to full sized truck.
That then leads to cavitation as the main common attribute. Bet all
in potentially very cold ambient that can cool the tank quickly
Then why cavitation is an issue. Think combo of amines softening and/or
affecting the bonding tension to have it come apart during cavitation
to then both create debris and exposed metal on metal....to both create
more debris and lost co-efficient of friction...to...then destroy itself
to create even more debris
Does that membrane filter have a pressure threshold ? Then ask what
is the PSI's (tolerance) at that membrane? Also, it's efficiency
(percent blocked vs passed...then at what PSI's/concentrations/saturation's/etc)
Again, this seems to me to lead back to cavitation and HOW2 manage
or eliminate cavitation
Based on VW's response to the NHTSA request with data from June 2010 to Jan or Feb 2011 for failures that had been reported to NHTSA, there seems to be a correlation to heat of the summer operation starting the snowball effect of failure and contamination of the fuel by material shed by the HPFP getting in and contaminating the fuel. Then there is the lag period of 1,2 maybe 3 tankfuls of fuel, before the destruction turns to failure. Based on that alone, I would say it could be heat related, or if in humid climates, also moisture related... many failures in California, Texas and Florida, all coastal states, but not with the humidity of the midwest all summer long. Think of a spiking of failures between July and December, with Sept and October being peak periods of failures. Every year, 4 years straight, VW and Audi go into severe backorders for full "kits" instead of a parts list /Bill of Material, for a HPFP failure, during Late August through October, with 2 to 3 week waits for the parts to arrive from Germany. Bosch is also making the HPFP's the 4.1's elsewhere besides Germany now... I thought I read Hungary in a post recently? No... Czech Republic.
http://forums.tdiclub.com/showpost.php?p=3719421&postcount=2906
http://forums.tdiclub.com/showpost.php?p=3733303&postcount=3000
No one here has mentioned alignment issues of the roller in the piston getting out of alignment with the cam in the HPFP, due to harmonics of the follower spring inside the piston causing rotation of the piston at certain rpms? This causes the roller to chip both at the cam when out of alignment, wear unevenly so it no longer is cylinder in shape, and dig into the outer sections of the DHC on the roller follower.
No one has also mentioned material of the bore, being aluminum, and the piston being steel. Which is the sacrifical metal?
No one has mentioned that this pump runs higher pressures, runs on one roller versus 4 in previous iterations in the Bosch VE series pumps, and runs at crank rpms versus half speed or same as the cam rpms on a 4 stroke motor, ie 2 x the rpms as in previous iterations. That is a hell of a lot to ask of your materials to still get a MTBF of 300 to 400,000 miles on the motor.
