greenprodrive

Hi,

I'm getting a weird noise , at around 3000 rpm.

It sounds a bit like a large brass instrument being blown softly (!). , quite a low ptiched sound.

Sorry, crap description .. any ideas anyone?

Thanks - Mark

smiff99

Sounds like the dumpvalve, had the same problem with mine, changed it for a Forge rc, problem solved.

Jon.

Butty

iTrader: (2)

As you have a 98 car then this noise is a faulty std dump valve.

Nick

greenprodrive

..

thanks guys,

actually , I replaced my old one, with a second hand one , when I rebuilt some stuff.

I guess the second hand one must be faulty.

(Is it possible to tell by looking ? .. it looked fine , but of course, that was when it was off the car).

thanks - Mark

Butty

iTrader: (2)

Can't tell by looking - its the recirc of air as the DV opens up prematurely.
The only symptoms are that it happens on 97-98 cars, at 3-3.5k rpm and sounds like you are blowing over the top of a bottle.


NIck

greenprodrive

Nick , that is a perfect description. thats EXACTLY wht it sounds like !.

Now that engine is on the car, .. is it a big job to fit new dumnp valve ? .. any hints/tips/things to watch for ??

cheers -Mark

Butty

iTrader: (2)

Its a 15 minute job. Disconnect the boost feed and two larger pipes.

NIck

scoobyboy1

iTrader: (16)

Glad I saw this thread, as Ive just had the same problem happen today on my 2004 WRX, theres a loud scream when the turbo kicks in. Ive upgraded my intercooler with a STi version and running STi dump valve, do you think my dump valve is broke.

smiff99

Not sure you have the same problem if you say it sounds more like a loud scream but don't rule it out.
A faulty dv sounds more as Butty described it, "like blowing across the top of a bottle" or like an old school police whistle.
I know this is more of a common fault with earlier MY's but mine failed on a MY99 STI.
Do you know of anyone with the same dv that you could try ?
Best to check it out before you look at other possible more expensive causes such as the turbo.

scoobyboy1

iTrader: (16)

My biggest fear that it might be the turbo, ive had a oil leak from the turbo that has recently been fixed, and a coolant pipe to the turbo which has been fixed now.

It only happens occasionally, Most the time in 3rd gear and you floor it, and the boost kicks in.

smiff99

Was the turbo removed ?

If it was maybe It's worth checking that everythings has been put back correctly, i.e. no leaks on the up or down pipe.

Check all the hoses that run boost.

Also worth checking that turbo heat shield is tight and not touching on anything.

scoobyboy1

iTrader: (16)

Turbo heat shield has been left off, as I had to fit the coolant pipe, I might try to tighten the jubilee clip on the boost pipe.