Piston Dump Valve.....All I get is chatter
Turbo Mini Forums

Another, quick question.

My dump valve doesnt seem to work. Its a piston type and im running at 8psi.

All I get it turbo chatter when I lift off or change gear. Dump valves meant to stop that isnt it?

Is there any way to cehck if a dump valve works?

Its plumbed in so that the big end comes off the plenum then the small pipe goes back into the inlet mani.

THe boost gauge is also tee'd off the small pipe.

Cheers

James.

Hi James, could be that its just staying open? sometimes the piston types don't work as well on the set-ups we use.

Hmmm,

I didnt actually look to see if it was staying open. Il have a look.

What type of dump valve would you recommend?

This is my set up:

Edited by hammoj28turbo on 23rd May, 2010.

Just a thought, if it was stayin open i wouldnt get any turbo presure or boost would I?

It certainly boosts fine and you get chatter our the turbo......

Most people use a diaphragm type. You can upgrade the rubber diaphragm to a kevlar based one as a reliability measure and mount it horizontally or pointing down so fuel vapour doesn't damage the diaphragm, as far as I remember

On 12th Nov, 2009 Paul S said:

I think Gary OS has taken over my role as the forum smart arse

loads of people have had dump valve problems. most problems, if not all functional problems can be cured by installing the dump valve with the vacum take off pointing down at the road

i started off with a piston type DV and changed it to a diaphragm type and as said above upgraded the diaphragm to a kevlar.

Mine would open and the not close.. both were / are mounted as yours - no probs with the diaphragm type mounted in the same position.

Might have to go with the diaphragm type then. But il try mounting mine differently first just to see.

Are there any certain valves I should look at? Are branded ones important?

Edited by hammoj28turbo on 23rd May, 2010.

wheres the vacume coming from to operate it, from the proper spacer pate or the one that comes on the metro manifold, the latter wont work

As Wolfie says, the stanard dizzy take off or the lean off pipe won't work.

I bought a spacer plate from mini spares which goes on between carb and mani for an extra take off.

If it's second hand it might have seen some fuel and the seals could have swolen, normally it sticks open when this happens though. My piston one will move with some firm hand pressure, try and see if it's sticking.

i had a similar problem with my bailey dump valve, it diddnt work correctly because the piston valve was dirty, i put some 3 in 1 on it and it worked fine untill it got dirty again... i have recently upgraded to an apexi twin piston type and it works perfectly all the time (bit big though lol)

ifi your using silicone pipe, make sure its no go any small rips in it near where its been put on the nipples, as it can easily break when bent quite a bit...

Still not got this working. Its a twin piston type i found out.

I changed the spring because it was a 22psi spring in it so got a lower rated one.

Still dont work. When you rev it at idle the large alloy piston moves but the small nylon one stays shut. So it can obviously move it it just doesnt seem to work.

Iv not yet tried mounting it upside down. Still need to do this.

Hmmm, made it face down the way.

Seem to get chatter then a few seconds later it dumps slowly.lol

Think the valve must have something wrong with it. Iv had it apart.

Thinking of just getting a diaphragm one like this and hopefully that will sort it:

try a diaprham one first

Yeah, im gonna go for that one above. Think that sounds the best bet n hopefully will sort out this problem.

Edited by hammoj28turbo on 26th May, 2010.

i have a forge one it works well on the mini

i use one just like the pic above - works great.

Cool, il give it a shot then and see what happens.

Pull the piston one apart and ceck the seals. Mine had swollen and split in 3 places causing it to stick closed.

In the 13's at last!.. Just

this is strange, i used to have a bailey dump valve (diaphragm one) and it never worked right, but then i got an apexi one and its perfect! its adjustable so no need to take apart and change springs plus you can move a ring to change how loud it is... worth a look on ebay! i got mine 2nd hand for £65