Hissing noise coming from engine...help!

[adam_may]

I have got a hissing noise as though i have a split in a boost pipe. Whats confusing me is that the hissing is only there when im at very low revs. If im on a hill holding the car on the biting point or setting off it hisses like mad but as soon as the turbo kicks in the hissing shuts off and it sounds like normal again! When changing gear it hisses if im just feathering the throttle but as soon as i put more gas on the hissing shuts off. Any help would be great. The car is a mk5 golf 2.0tdi. Thanks adam

[mortygttdi]

Sounds like a possible vacuum hose off somewhere 3 places to check 1)The small vacuum ball reservoir at the front the 2)The EGR valve at the front of the engine also, 3) There's a black box at the rear of the engine just behind the battery with loads of vac hoses going to it check all are on and that none of the nipples are broken

There is an hose at the back of the engine going to the turbo but if your turbo is spooling up fine its possibly fine

[adam_may]

Okay mate thanks alot for that ill check it out this weekend!

[adam_may]

the lower boost hose popped off at the weekend as 1 of the lugs snapped off, new pipe from VW £40 problem solved....hissing noise has gone and cars running spot on!