mk4 gt tdi 130 turbo hissing noise - wastegate?

[leemasiuk]

Check the boost pipes for leaks...tighten everything that looks or seems loose.You have faults stored in the memmory that will need erasing. All should get back to normal after that. Hope this helps.

thanks for that. i intend to check for loose pipes and splits etc.

only thing is i am pretty much a novice with my car (mk4 gt tdi 130). i dont know where the boost pipes are located. whats the best way to find out what pipes i should be checking?

[Alun]

Is the car fitted with an intercooler? If it has then you've probably got a split/corroded pipe going to/from the intercooler.

[moff]

mine does it on my golf to but i just thoughtit was just my turbo whinding up then when i lef the revs off and change gear i can hear air being let out like a dump valve

[Eshrules]

i suspect there may be a little confusion here between the 'normal' turbo sounds and the sound of a split hose....

if you can hear the noise from around 1700rpm to around 3000rpm (by which time the noise of the engine will mask it)...then i would suggest that it is probably just the turbo doing its job, ie sucking in the extra air it is there for. if you accelerate harshly and gear change quickly, you will notice a slight hiss, this is the wastegate doing its job also and releasing the excess boost pressure.

however if the 'hiss' is a constant noise and doesnt appear to alter with the revs of the engine through the gears, that to me would suggest a leak.

the turbo noise will tend to increase with the more gas you give the car...

also, if you have a boost leak, you will notice a severe lack in boost pressure and your car would probably lag around 400/500 rpm more than usual.