Hmm... I’m pretty sure I’ve seen 603 IPs with the sealed ball spring thingy vs the 617s removable bolt style. But I don’t bet on my memory.

This is a 602 IP but that thing with the ball is an orifice rather than a spring valve?



How about vacuum in the fuel tank?

Sixto
98 E320s sedan and wagon
02 C320 wagon

The pressed ball bearing seals the assembly and the weak spring and disc valve inside. The disc valve serves as a non-return valve, it does not regulate pressure. You can blow through one of these types of valve with your breath the spring is that weak. Pressure is regulated by flow resistance against the orifice.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]