I've just copied this from the SIDC web site..

Fault:
Blow-off valve (Dump Valve, Air bypass valve)

Symptoms:
Loud noise between 2-4000 rpm that sounds like someone blowing over top of a bottle.

Models Affected:
1997/1998 Turbo

The Problem:
There seems to be a recognised problem with the 1997 specification car's dump valve. This does not shut properly under boost and thus vibrates giving the sound similar to someone blowing across the top of an open bottle. It has also been likened to a steam train whistle or ship fog horn in extreme circumstances!. Meanwhile the 1998 model seems to have a totally revamped and larger blow off system, but I have had reports that the problem sometimes still occurs.

Has anyone else experianced this problem? If so, have you managed to solve the problem and how?

Cheers,

Shaggy..

 

Not had the problem but the solution is to buy a new dump valve

 

I had this problem on an MY97, took it to TSL who had never heard of it being a problem. When I explained the details, Trouser's dad told me that I had been reading too many bulletin boards! Anyway, I told them to change the standard dump valve to a forge one and I have not heard the noise since!! Goes to show that BB's are useful! (especially Scoobynet).

PS He also told me that my K+N induction kit was the worse mod that I could do to a Subaru! I will stick with it.

 

555-Shaggy, dont worry...standard dv leaking, sound increases as the boost (pressurised air) increases.

The cure, as others have said...buy a replacement.

Range from around £80 to £250!

Cheers, MD.

 

Chod,can you tell us what TSL said about K£N induction kits as I have one and dont want to knack anything up at the moment.

 

I was also told that induction kits were the worst mod to make by Trouser himself.. The reason was that on a standard set up the air is taken from inside the wing not the engine bay and is therefore cooler.. The induction kit gets the air from the engine bay therefore warmer.. Having since looked, I think the air is sourced from the engine bay and routed into the wing and out again to air filter, I have been told there is a chamber inside the wing that dulls the induction noise.. So, why not fit an induction kit then if the air comes from the same source?

 

Shaggy

When we wrote the FAQ, it was a common problem. Most were changed at the time under warranty, which is why some people will not have seen any problems with them.

That said, there are still plenty of cars out there that have the early part number (can't remember what it is, before you ask), its just that they have lasted until now.

At the end of the day, the part will eventually fail anyway, so I'd bite the bullet and replace it either with another Subaru one, or with a nice shiny one.

If you want any help, please ring.

 

Thanks everyone... looks like mine just slipped through the net.. Oh well, look out credit card, here comes a nice shiney dump valve.. Suggestions anyone?

 

He told me it was the worst mod due to the warm air from the engine bay. I figure that Graham Goode know what they are doing and they not only sell the K&N but also make one of their own.

I would be interested to know of anyone who has rr'd their car without and then with an induction kit.

 

I agree with 555 Shaggy in that the air is directed from the same source as long as you leave the bottom of the air box and the pipes going into the wing as K&N request in their instructions so the air comes from the front grille to the filter (as normal air box does).The only down side I supose is when you are stuck in traffic it will draw in heat from the engine bay but at speed it should be the same.

 

go for the HKS one,you can change the fins inside to get the sound you want too!