Dump valve woes
Turbo Mini Forums

Can any1 help please?
Im running an intercooler and between the intercooler and carb ive fitted a dump valve. However im struggling to find a suitable vaccum take off. Ive found 2: first is on the top of the inlet manifold quite large and when i attach a hose from here to the dumpy the car cuts out. second is between carb and manifold and doesnt provide enough vaccum to open the valve, this is where ive plumbed my boost guage into. Can anyone please give me any ideas how to get it working?

1986 renault 5 gt turbo
1989 Renault extra
1991 R32 GTR
1998 Mini MPI
1999 Nissan Elgrand

What is normally attached to the top of the inlet manifold?
Fitting the vaccum pipe from the dump valve shouldnt make any difference as it still souldnt be able to draw any air in

Whats going to break next!?

Turbominis Worst Advice winner 2006, get in

I had same thought.

Hi,
Check your dump valve hasn't got a split diagphram (SP?) If that's ok how about a pic to see if we can sort it that way?
Cheers,
Gavin. :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

My Mini build diary

The take off between carb and manifold if fed from the other side of the butterfly, so wont make the pressure differential to operate the dump valve, and as you say the centre servo- take off is too large to use, you need to blank this off... a spare crank damper bolt fits perfect.

You need to drill/ tap a new small take off on the Inlet Manifold.


hth

Edited by Kean on 10th Jan, 2006.

hey there mate i saw a picture of the avonbar turbo engine and the dump valve was plumbed in with a tee piece from the pipe on the carb witch gos from float chamber top ithink to the bolting flange (down draft of the butterfly(but i havent tryed it there yet myself

Hi never posted a picture this way before so i hope its ok!
http://retrocarclub.co.uk/forums/uploads/p...05083_thumb.jpg
Hope thats right the numbers starting 323 is the url number whatever that is

1986 renault 5 gt turbo
1989 Renault extra
1991 R32 GTR
1998 Mini MPI
1999 Nissan Elgrand

Thanks Tom

1986 renault 5 gt turbo
1989 Renault extra
1991 R32 GTR
1998 Mini MPI
1999 Nissan Elgrand

when you use the large take off in the centre of the inlet are you using the original connector thats standard on the metro? if you are it wont work as it has a one way valve in it.

As kean has said above the take offs on the carb are the wrong side of the butterfly to use as a dump valve trigger (we know this because we found out when we fitted my first DV)

Avonbar do sell a small spacer plate that sits between the carb and inlet that has got a nipple on the top of it to use as a boost gauge feed or dump valve trigger. Otherwise you can drill and tap/weld a nipple onto your inlet manifold.

i'll take a pic of mine tomorrow if you want as i'm doing a bit of work on it at the mo anyway.

Edited by Nick on 11th Jan, 2006.

The large take off i talk about is the servo vaccum but i dont use a servo you can just make it out under my boost hose in piccy with small black tube on it. if i block it off with my finger or fit it to a dump valve the engine dies. Behind this is a spacer with a take off in it but this doesnt provide a vaccum just positive force which is ok for the boost guage but not the dumpy. I think the servo take off is sucking in that much air that the spacer one hasnt got chance

1986 renault 5 gt turbo
1989 Renault extra
1991 R32 GTR
1998 Mini MPI
1999 Nissan Elgrand

does your boost guage work ok? (show boost and vacuum?) if your guage shows vacuum then you know that thats ok, and the dumpvalve is at fault. if you are using the one way valve (obviusly not intentionally) it should open the same but wont push closed but the spring in the valve should hold it closed for at least 9/10 psi.

HTH Dan

Boost guage is only showing pressure not vaccum

1986 renault 5 gt turbo
1989 Renault extra
1991 R32 GTR
1998 Mini MPI
1999 Nissan Elgrand

In that case it won't work. You need to move your dump valve trigger to a point where there can also be vacuum, e.g. on the engine side of the butterfly.

Have tried this. Thats where its mounted now- on the spacer between carb and manifold but i think the servo vaccum take off on the manifold is dragging too much air in to let the other work

1986 renault 5 gt turbo
1989 Renault extra
1991 R32 GTR
1998 Mini MPI
1999 Nissan Elgrand

The servo take off should pull a negative pressure on the servo. Once it has done this, you will not get any more air travelling down the pipe from the servo. If there is air being pulled down the servo pipe all the time, it means your servo diaphragm is holed.

I'm not running a servo its just pulling in air from the engine bay but if i block it or fit to d/v car cuts out

1986 renault 5 gt turbo
1989 Renault extra
1991 R32 GTR
1998 Mini MPI
1999 Nissan Elgrand

In that case, you need to block it off, and then increase the idle screw until the car idles properly.

It will not be running properly or boosting properly with that connection open all the time!

If your not using that take off it needs to be blocked off, end of story, otherwise the engine will lean out...

Block it off and get the engine setup proerly without the dumpvalve on so that it runs correctly.

Then fit the dumpvalve and make sure it is connected to the manifold side of the throttle, and is only fed by a small pipe/outlet.


if you could take a better picture of how it is actually fitted, we could describe it better to you.

oh and fill in your profile, were are you if you are close is i am sure anyone on here will be more than happy to sort it for you.

Thanks fellas i have noticed it pinking a litle lately i guess this must be why altough its still making pretty impressive power.
Just for the record i live in Grimsby N.E. Linclnshire if anyone is nearby.

1986 renault 5 gt turbo
1989 Renault extra
1991 R32 GTR
1998 Mini MPI
1999 Nissan Elgrand

about an hour and half from me then so not really round the corner lol.

As I said, block the hole off, then keep screwing in the idle speed screw until it will then run again. It will probably then need setting up properly.
You ABSOLUTELY NEED to STOP! it pinking unless you want to really do some serious damage to it, e.g.scrap pistons.

Sorry Tom, posted same time as you lol.

No bother!