.
thanks mate I finnaly got that right ... i google some pictures and find that small cap called delivery valve
my pump had to be PES5mw 55/320 RS16 I guess it has no significant difference with RS15 model
anyone happens to know bosch part number for those d valves?
and yes,you are quite right about those guys but I have to stick with them
for a few days more and if they don't resolve issue after rebuilt I have good ground to engage lawyer
edit; I regret not seeing this post before
http://www.peachparts.com/shopforum/diesel-discussion/310112-symptoms-bad-ip-delivery-valve.html
.