I replaced the top hose a few days ago due to leakage trom the plastic section. The valve you described isn't on the top hose but attatched to a narrow aluminium pipe, one end travells along the " V " section of the engine towards the bulkhead and the other end travells along the inner near side wing and down towards the bulk head. There is however what looks like a valve on the plastic section of the top hose, it has a slotted section in the middle probably for a screwdriver and in very small lettering says "service only" and is positioned directly below the large pipe from the air filter.