bosch pump hissing air.

[fieldofrob]

that's a breather at top of pump to vent pressure.

how can you tell it's leaking air is it hard to start or something?

so that breatheris to vent pressure/air out but does it have a oneway valve to stop air getting in? a few members seem to be having the same issues

aha, so would it vent to the atmosphere? I've been looking at ve pump diagrams but can't spot anything, perhaps it has a oneway that's failed but ive no idea where, not where the boost diaphragm thingy vents to???? hmm, tricksy bloody problem.