Coppin1991

Hi people, I have a Subaru Impreza 1999 Turbo 2000 and i was just wondering what the correct size for the dump valve vacuum hose is as the one on my car is a 6mm silicone blue hose but after doing some research i see that alot of people say that a vacuum hoses need to be a 3.5mm?

Really the main problem I'm having is when I'm on boost and release the throttle as i had a VTA dump i expect a loud whoosh sort of sound, But theirs next to no sound at all so I'm just sort of checking off things that could be the problem if anyone could help and maybe if you had the same problem I'm having to let me know how to get it sorted out would be a great help.
thanks

piehole1983

iTrader: (7)

Mine has a 4mm internal diameter (about 7/8mm external diameter) hose going to the BOV. What type of valve is it? When I got my car my valve was completely seized!

Coppin1991

Well I just brought the new dump valve it's a forge venting to atmosphere, and I just brought a 4mm hose so when I receive it I'll see if it makes a difference but the dump valve doesn't seem to make any sound at all when I come off boost and I can't figure out what else could be causing the problem

piehole1983

iTrader: (7)

The only thing I can think of is where it's connected to really. Mine goes straight to one of the ports on the intake manifold. There's a larger one, mine is on that one.

Coppin1991

Yeah I'm sure mines on the same port
When your looking down on the engine it's the port on the right side out of both ports and also the port on the left has a small hose bent around to sort of blank it off so what's that port used for?

piehole1983

iTrader: (7)

It can be used for anything that needs to be connected to the intake, boost gauge etc. I think mine are all used up!

Coppin1991

Oh ok well that's why mine has been blanked off I haven't got a boost gauge I have a PSI3 ECU Data Monitor it shows boost, car temperature, rpm, etc etc
Well I have got a problem with the down pipe that connects to the turbo, basically there's only 4 studs holding the downpipe on instead of the 5 that's suppose to be on there's and the turbo has to come off as my mechanic told me the fifth stud has been snapped in the turbo so it's losing some power due to it leaking air from the downpipe so could this also be the reason the dump valve ain't working properly at all mate

Dutch Scooby lover

iTrader: (3)

The leaking exhaust will not cause a loss of boost pressure, it is after the turbo.
Maybe the spring inside the Forge is too stiff for the boost level you are running.

They do 3 spring types, yellow, blue and red I believe, with yellow being the weakest, the blue and then red.
If your Forge has a red one fitted but you are only reaching 1.0 or 1.1 bar boost pressure you will have this non venting problem IMO.

Coppin1991

Well I thought it would be the spring but when I brought the dump valve I asked them to put a yellow spring in as I only get about 1.0 bar of boost but I will check what spring is in it just to make sure will I have to take it to a mechanic to check the dump valve or is it an easy task to do?