dump valve question

[1999v70r]

if i fit a dump valve and blank off the vacuum pipe to the original would this disable it until my blanking plate arives? as the vacuum makes it open no vacuum means it cant open so uses just the atmos valve am i correct in saying this or not

[p fandango]

no, the recirc valve relies on positive pressure from the manifold to keep the valve closed when the turbo comes onto boost. If you take the pipe off it'll get blown open & you'll lose boost

[snoop69]

Get yourself a oneway valve from Halfrauds to keep the pressure in the vac
line to the re-circ.

[1999v70r]

could you eplain a little more ithought the re circ had to be disconnected/removed for it to work the new valve

[snoop69]

Pressure in the vac line keeps the recirc closed hence the reason for the
one way valve.

The valve keeps the pressure to the recirc & boost is now dumped via the DV.

If you didnt keep pressure to the recirc you would probably get a boost leak.

[1999v70r]

so could i just put the vac pipe of the new valve on the vac tree and leave the re circ

[snoop69]

so could i just put the vac pipe of the new valve on the vac tree and leave the re circ

You could but it would dump from both.

Its cheap enough to install a one way valve to keep the recirc from dumping.

[1999v70r]

yeah just realised what you ment should have read it properly first thanks for your help

[p fandango]

your MAF's unplugged lol

[snoop69]

your MAF's unplugged lol

I know lol.

It was knacked & ran sweet as a nut un-plugged confirming that the Maf
had croaked it.

[p fandango]

I know lol.

It was knacked & ran sweet as a nut un-plugged confirming that the Maf
had croaked it.

i've ran with it unplugged before, purely because i forget to put it back after messing lol

[HairyDave]

Forgive me for bringing up an old topic, but i've just bought a DV36 off fleabay and a fitting kit for a 850t5 and was planning on using a one way valve on the line going to the re-circ so if I decide I don't like the noise I could easily convert back.
The problem is which way should the one way valve point??
The pipe is coming from the vac tree, so one would presume the re-circ is held closed using the vacuum whilst accelerating, then as the vacuum disappears(when you lift off) it releases the pressure through the valve.
So how does it convert a negative pressure to a positive pressure to hold the boost?

So should the one way valve point to keep a pressure in, or a vacuum in?

Regards, David

[p fandango]

you want the pressure trapped into the recirc valve so the arrow pointing towards it

[HairyDave]

Cheers for clearing that up. I fitted the dv this morning, went for a spin and the car is not happy. There was a massive lag when accelerating, the tick over was lumpy and at one point it cut out with the dash looking like a christmas tree. Swapped the pipework to cut out the dv and put the recirc back in and all is fine. Apart from the lambda light on. Is this serious? Didn't think there was all that much to go wrong with this!

[HairyDave]

Hehehe. Numbnuts here only went and bought the wrong valve! It's the single piston type, so is breathing throughout the dv and throwing out the ecu. This seems to have read a sensor fault. I swapped the pipework around so the one way valve is causing the dv to stay closed and after a few miles the light went out, as well as the running improving.
It sounded good though. Think I may just fork out for a new valve, garunteed to fit my car instead of messing around on the worlds biggest car boot. Think he may have swapped the part as it looks a little different to what his photo showed.....

David

[gmain1967]

Hehehe. Numbnuts here only went and bought the wrong valve! It's the single piston type, so is breathing throughout the dv and throwing out the ecu. This seems to have read a sensor fault. I swapped the pipework around so the one way valve is causing the dv to stay closed and after a few miles the light went out, as well as the running improving.
It sounded good though. Think I may just fork out for a new valve, garunteed to fit my car instead of messing around on the worlds biggest car boot. Think he may have swapped the part as it looks a little different to what his photo showed.....

David

Are you sure this is a single piston valve? I'm presuming you got a Baileys DV-36, or DV-36D, both of which are twin piston type designs, specifically intended for cars with airflow meters.

Is it perhaps a DV-34 you have, which is a single piston type valve?

[HairyDave]

Right. My DV-36 came yesterday. Deffo the right one as I bought it from a reputable source. Plumbed it in and the car seems to run okay and the valve seems to work, but only when the engine is under load. When I rev the engine, say at the lights, Their doesn't seem to be enough volume of air to escape. Is this because I have the low pressure engine and it Just doesn't need to vent as much and am I expecting too much?
Never seen a volvo with a DV, so not too sure what to expect.

Regards, David

[p fandango]

Right. My DV-36 came yesterday. Deffo the right one as I bought it from a reputable source. Plumbed it in and the car seems to run okay and the valve seems to work, but only when the engine is under load. When I rev the engine, say at the lights, Their doesn't seem to be enough volume of air to escape. Is this because I have the low pressure engine and it Just doesn't need to vent as much and am I expecting too much?
Never seen a volvo with a DV, so not too sure what to expect.

the turbo will hardly make any pressure if the engine isn't under load so your right in theirs not enough air to escape

[HairyDave]

It would help if I put the one way valve in the right way round!
The black side goes towards the vacuum tree! Why did something so simple go wrong?!?! Anyway, all sorted now and my car is farting like a trooper! Hehehe!
Cheers for all your help, bunch of top geezers!

David

[mightywolf]

Mines an auto and the only way i can get it to dump if i'm stood still is to rev it to 3000rpm or above and let straight off the gas.