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One for the turbo experts.
stevec - 15/9/07 at 08:54 PM

I am running the standard Rover 1.8 Turbo set up.
I am getting a very loud light throttle hissing from the area of the air filter.This goes away when more load is applied and is not there at full throttle. This is not the same noise as the usual induction roar. it sounds more like a compressed air gun. The air filter is a K&N capable of use on twice the power output of mine so I dont believe its restrictive.
Due to lack of space the air filter is in the passenger footwell so this makes it more noticeable. I reckon I will probably have to live with it.
Any clues anyone?
Cheers.
Steve.

oadamo - 15/9/07 at 10:00 PM

if its a hissing its a leak on the compressor side. do you have a bleed valve.
adam

stevec - 15/9/07 at 10:43 PM

Its hissing before the boost gauge is reading positive pressure and the noise is from the inlet side,
Steve,

PAUL FISHER - 15/9/07 at 10:49 PM

Sounds like its the turbo waste gate fluttering,opening and closing to me.this is the noise you here each time you change gear,or throttle off.With the noise going away under engine load,if it was a leak on the pressure side I would expect it to be hissing louder under full throttle and boost.And with you having the induction in the footwell as I have on my car this noise will be amplified.

[Edited on 19/05/04 by PAUL FISHER]

Fatboy Dave - 15/9/07 at 11:01 PM

More likely to be the recirculating dump valve being open on part throttle. At light throttle the turbo is most likely not making boost therefore the wastegate will be closed and thus silent.

When I got my first Rover turbo (a 620Ti), I was alarmed at some of the noises the stock recirc DV used to make when I binned the air box and fitted a chav filter...

grub - 16/9/07 at 07:11 AM

is there much float on the impeller, and its not rubbing on the compressor housing just a thought i know that makes a strange noise??

stevec - 16/9/07 at 09:40 AM

quote:
Originally posted by grub
is there much float on the impeller, and its not rubbing on the compressor housing just a thought i know that makes a strange noise??


Turbo and engine are New. No play in anything.
Steve.

martyn_16v - 16/9/07 at 04:14 PM

How far is the throttle from the air filter/end of the inlet? One of my old cars used to hiss like a python being bothered by Steve Irwin at part throttle, it was just air rushing past the nearly closed throttle butterfly. Just put your foot down