Piston dump valve question
Turbo Mini Forums

Guys

After lots of searching and reading, I need some advice with a dump valve problem.

After a while, the piston dump valve I fitted appeared to stay open at idle and was audibly letting out air at cruise and very slow to shut with closing of the throttle on boost.

The piston has a green O seal (which I am assuming is Viton) which was swelling as it appeared to have been saturated in fuel coming from the boost pipe connected to the manifold.

I changed the O seal to a smaller one, gave the piston a smear of petroleum jelly and re-positioned the valve so that it was pointing downwards to help drain any fuel back to the manifold.

It's working alot better but the DV is open and leaking air in at idle and at cruise which is doing my head in.

The DV came with two springs and recommends that the one I have fitted is good up to 15 psi.

The other spring in the box is alot stiffer and says it's good from 15-30 psi.

Assuming I fit the stronger spring and that this will probably keep the piston on its seat for longer thereby stopping the air loss ......

a) will I lose the low boost (less than 15 psi) performance of the DV ? and

b) will it do my compressor any harm ?

Thanks.

Richard.

Attachments:

289.63kb

210.76kb

Edited by turbominivanman on 1st Apr, 2010.

Minivanless, but reluctantly happy living with the decision. There'll be another one day.
http://www.youtube.com/profile?user=minimadmotorman#p/u

Any help guys ?

Many thanks

Richard.

Minivanless, but reluctantly happy living with the decision. There'll be another one day.
http://www.youtube.com/profile?user=minimadmotorman#p/u

I,m the last person to offfer advice, but I have been told to fit my dump valve"the other way round"
Does this make any sense to you and your problem ?
(thought not)

if you fit a stronger spring the dump valve may fail to open al light loads, whats the diameter of the spring? try a shim, washer or even a 2p? just to test it
my first choice of dumpvalve would be a HKS SSQV well worth the money

Yes i moved to the darkside

Instagram @jdm_brett

Yes Dave, it does make sense.

Keeping the DV so that the small boost connection is pointing downwards reduces the chance of fuel contamination coming from the manifold.

But what about the effects of the stronger spring ?

Any ideas guys ?

Richard.

Minivanless, but reluctantly happy living with the decision. There'll be another one day.
http://www.youtube.com/profile?user=minimadmotorman#p/u

Minivanless, but reluctantly happy living with the decision. There'll be another one day.
http://www.youtube.com/profile?user=minimadmotorman#p/u

Are you just concerned about the valve allowing air in at idle/cruise Richard?

They pretty much all do this, mine sits wide open at idle whilst the trigger line is under vac.

Mine is adjustable, and the harder you set it the more boost it takes to operate, increasing compressor stall noise when you shut the throttle at low boost.