Defender 200 tdi Dump Valve - Whats the point?

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J

Jon

Guest
Just a quick question...

I'm setting about extending breathers up the snorkel and sealing up
the airbox etc and came to the dump valve - whch set me thinking.

What is the point of this silly bit of rubber?? When the turbo is
sucking air the valve 'closes' and pulls air from the air inlet
(snorkel) and when you lift off and get back pressure to the turbo the
excess pressure can release through the snorkel that is not 3 feet
away?

So can I just seal it up so I havent got one anymore or am I missing
something fundemetal in my thinking.

Whilst I'm on this subject, mine isnt really that clever at sealing
itself under vaccum anyway - should I replace it or just seal it up?

Any thoughts or advice welcomed.

Thanks
Jon

 
Jon wrote:
> Just a quick question...
>
> I'm setting about extending breathers up the snorkel and sealing up
> the airbox etc and came to the dump valve - whch set me thinking.
>
> What is the point of this silly bit of rubber?? When the turbo is
> sucking air the valve 'closes' and pulls air from the air inlet
> (snorkel) and when you lift off and get back pressure to the turbo the
> excess pressure can release through the snorkel that is not 3 feet
> away?
>
> So can I just seal it up so I havent got one anymore or am I missing
> something fundemetal in my thinking.
>
> Whilst I'm on this subject, mine isnt really that clever at sealing
> itself under vaccum anyway - should I replace it or just seal it up?
>
> Any thoughts or advice welcomed.
>
> Thanks
> Jon
>
Isn't it supposed to allow oil and general **** to escape the intake area?

`Mark
 

>>
>Isn't it supposed to allow oil and general **** to escape the intake area?
>
>`Mark

This would probably be a better explanation than mine, but then it
isnt a true dump valve!?

If this is all its for I suspect it can definately be sealed up.

Jon
 
So Jon was, like

> Just a quick question...
>
> I'm setting about extending breathers up the snorkel and sealing up
> the airbox etc and came to the dump valve - whch set me thinking.
>
> What is the point of this silly bit of rubber?? When the turbo is
> sucking air the valve 'closes' and pulls air from the air inlet
> (snorkel) and when you lift off and get back pressure to the turbo the
> excess pressure can release through the snorkel that is not 3 feet
> away?
>
> So can I just seal it up so I havent got one anymore or am I missing
> something fundemetal in my thinking.
>
> Whilst I'm on this subject, mine isnt really that clever at sealing
> itself under vaccum anyway - should I replace it or just seal it up?
>
> Any thoughts or advice welcomed.
>
> Thanks
> Jon

Depends on the set-up on your vehicle, but on my 90 n/a it was vital. The
intake on the wingtop lets in water to the air intake, and the dump valve
allows it to drain out. Whenever I'd got it really muddy and the dump valve
got sealed by the crud, the water would accumulate and next time you turned
on the heater all the windows misted over. Quick proggle of the rubber
valve and you could see forward again. Quite important, really.

--

Rich

Pas d'elle yeux Rhone que nous


 
On 2005-04-15, Jon <[email protected]> wrote:

> I'm setting about extending breathers up the snorkel and sealing up
> the airbox etc and came to the dump valve - whch set me thinking.

It's not a "dump valve" in the chavved-up nova sense, it's a water
release valve that is there to allow water to escape from the air
intake system. I think there's another one somewhere around the air
filter too.

Some people remove them when they fit a snorkel on the basis that with
a snorkel you're much less likely to get water, twigs and small
animals in the air intake system so the release valve's not needed so
much, and if anything the water release valve is more likely to let
water in than the snorkel is.

> So can I just seal it up so I havent got one anymore or am I missing
> something fundemetal in my thinking.

Seal it up, or leave it open, makes on odds really provided that
you're happy that the air intake system is reasonably water and
creature proof.

Some snorkels, e.g. the Safari one, have a box at the bottom of the
snorkel that extends below the line of the pipe leading to the air
filter, this box catches twigs and other crap that makes it through
the snorkel mouth. If yours has one of these, then even more reason
not to bother with the release valve.

For the record, the kind of dump valve I think you are talking about
(the one that kevs fit to their cars, and yes I've got one on one of
my cars) fits between the turbo and the inlet manifold, not the air
intake and the turbo. Unless you're not thinking about what I'm
thinking about.

--
For every expert, there is an equal but opposite expert
 

>
>For the record, the kind of dump valve I think you are talking about
>(the one that kevs fit to their cars, and yes I've got one on one of
>my cars) fits between the turbo and the inlet manifold, not the air
>intake and the turbo. Unless you're not thinking about what I'm
>thinking about.


so.... can you explain what the dump valves do on KEVS car, and should
i fit one? S`pose not, as my names Andy, im 38 and drive a Landy,
but i could start a craze, all the Kevs switching to Landys, souping
them up and hanging around car parks in town centres. Low profile
GRIZZLEY CLAWS and all.



andy

ps... im serious about the dump valve explanation......
 
dave wrote:

> so.... can you explain what the dump valves do on KEVS car,

On a petrol engine the inlet tract is blocked by the throttle butterfly
when the throttle is closed - this causes back pressure to the turbo and
thus stops it spinning. In the case of changing up a gear this leads to
a shot flat spot of no boost as the turbo spools up when you open the
throttle again in the higher gear. The blow-off valve (dump valve)
releases this excess pressure allowing the turbo to keep spinning on an
upchange thus allowing full boost immediately without waiting for the
turbo to spool up again. It's only of any real benefit on large turbos
that suffer excessive lag.


--
EMB
 
On or around Sat, 16 Apr 2005 09:23:08 +0100, MVP
<mr.nice@*nospam*softhome.net> enlightened us thusly:

>On Fri, 15 Apr 2005 20:10:05 +0100, "Richard Brookman"
><[email protected]> wrote:
>
>>So Jon was, like
>>
>>> Just a quick question...
>>>
>>> I'm setting about extending breathers up the snorkel and sealing up
>>> the airbox etc and came to the dump valve - whch set me thinking.
>>>
>>> What is the point of this silly bit of rubber?? When the turbo is
>>> sucking air the valve 'closes' and pulls air from the air inlet
>>> (snorkel) and when you lift off and get back pressure to the turbo the
>>> excess pressure can release through the snorkel that is not 3 feet
>>> away?
>>>
>>> So can I just seal it up so I havent got one anymore or am I missing
>>> something fundemetal in my thinking.
>>>
>>> Whilst I'm on this subject, mine isnt really that clever at sealing
>>> itself under vaccum anyway - should I replace it or just seal it up?
>>>
>>> Any thoughts or advice welcomed.
>>>
>>> Thanks
>>> Jon
>>
>>Depends on the set-up on your vehicle, but on my 90 n/a it was vital. The
>>intake on the wingtop lets in water to the air intake, and the dump valve
>>allows it to drain out. Whenever I'd got it really muddy and the dump valve
>>got sealed by the crud, the water would accumulate and next time you turned
>>on the heater all the windows misted over. Quick proggle of the rubber
>>valve and you could see forward again. Quite important, really.
>
>erm... the wingtop air intake only feeds the heater, not the engine...

exactly, if it gets water in it, it'll feed wet air into your demister.
--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Festina Lente" (Hasten slowly) Suetonius (c.70-c.140) Augustus, 25
 
On or around Sat, 16 Apr 2005 10:20:41 +0100, MVP
<mr.nice@*nospam*softhome.net> enlightened us thusly:

>confused the crap outa me, I think 'dump valve' and I think about the
>thingy in the manifold or a turbo engine rather than the little rubber
>wossit in the bottom of the air filter box.
>Is there such a valve in the heater box? spose there must be
>considering the intake is open-upwards allowing rain straight in.
>I'll ****-off now and do something useful....

there is indeed.

I've been doing something useful:

http://www.roman-road.co.uk/temp/P4170581.jpg
http://www.roman-road.co.uk/temp/P4170582.jpg
http://www.roman-road.co.uk/temp/P4170583.jpg

although it's not a land rover. 'tis long wheelbase, though...
--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Carpe diem, quam minimum credula postero" (sieze today, and put
as little trust as you can in tomorrow) Horace (65 - 8 BC) Odes, I.xi.8
 
On or around Sat, 16 Apr 2005 11:44:51 +0100, Dougal
<DougalAThiskennel.free-online.co.uk> enlightened us thusly:

>Austin Shackles wrote:
>>>I'll ****-off now and do something useful....
>>
>> there is indeed.
>>
>> I've been doing something useful:
>>
>> http://www.roman-road.co.uk/temp/P4170581.jpg
>> http://www.roman-road.co.uk/temp/P4170582.jpg
>> http://www.roman-road.co.uk/temp/P4170583.jpg
>>
>> although it's not a land rover. 'tis long wheelbase, though...
>
>Would it be picky of me to suggest that something is missing on the
>style front?

bah. form follows function, innit. besides, I've painted the chassis, now.
I might even paint the wheel and the top...

--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"Where they make a desert they call it peace" Tacitus (c.55 - c.117)
Agricola, 30
 
On 2005-04-16, EMB <[email protected]> wrote:

> It's only of any real benefit on large turbos that suffer excessive
> lag.

Well any turbo suffers lag, some greater than others, so it's of
benefit on smaller turbos too with relatively little lag. It's also
beneficial for the turbo reliability too as the backpressure from the
inlet manifold puts stress on the turbo that just doesn't need to be
there.

Lots of cars have dump valves as shipped from the factory, but
factory-fitted ones are recirculating ones that blow the excess air
back in to the intake system on the other side of the turbo, so doing
away with that woosh sound so beloved of the kevs.

--
For every expert, there is an equal but opposite expert
 
So MVP was, like

> On Fri, 15 Apr 2005 20:10:05 +0100, "Richard Brookman"
> <[email protected]> wrote:
>
>> So Jon was, like
>>
>>> Just a quick question...
>>>
>>> I'm setting about extending breathers up the snorkel and sealing up
>>> the airbox etc and came to the dump valve - whch set me thinking.
>>>
>>>
>> Depends on the set-up on your vehicle, but on my 90 n/a it was
>> vital. The intake on the wingtop lets in water to the air intake,
>> and the dump valve allows it to drain out.
>
> erm... the wingtop air intake only feeds the heater, not the engine...
>

That's the valve I thought he meant. The only dump valves I know are on
heater intakes, but then I've only ever had n/a diesels. Should have read
the post more carefully.

--

Rich

Pas d'elle yeux Rhone que nous


 
"Ian Rawlings" <[email protected]> wrote in message
news:[email protected]...
> On 2005-04-16, EMB <[email protected]> wrote:
>
>> It's only of any real benefit on large turbos that suffer excessive
>> lag.
>
> Well any turbo suffers lag, some greater than others, so it's of
> benefit on smaller turbos too with relatively little lag. It's also
> beneficial for the turbo reliability too as the backpressure from the
> inlet manifold puts stress on the turbo that just doesn't need to be
> there.
>
> Lots of cars have dump valves as shipped from the factory, but
> factory-fitted ones are recirculating ones that blow the excess air
> back in to the intake system on the other side of the turbo, so doing
> away with that woosh sound so beloved of the kevs.
>

I fitted a vent-to-atmosphere 2 piston dump valve to my 200tdi Defender
(mainly through boredom) as an experiment so see what effect it would have
on a diesel. You don't get the same increased vacuum when you let of the
throttle in a diesel which controls the valve on a petrol so I have it
electronically controlled off a throttle position sensor, this makes a
solenoid valve switch a branched feed from the servo vacuum to the dump
valve actuator.

To be honest the decreased lag is only marginal and although faster it makes
gearchanges less smooth than without. It's very loud as well so you will
feel like a **** driving round town but being electronic you can turn it off
when you think people might be in earshot. In all not really worth doing,
the novelty of seriously confusing the pondlife in Halfords carpark soon
wears off and the power advantages aren't practical and only very slight, it
should in theory however increase the turbo's life by eliminating the
backpressure & turbo stall.

Fergus


 
On 2005-04-16, news.virgin.net <frig> wrote:

> I fitted a vent-to-atmosphere 2 piston dump valve to my 200tdi Defender

Hehe, a dump valve on a Defender diesel! Most unusual.

> should in theory however increase the turbo's life by eliminating the
> backpressure & turbo stall.

Indeed, although it has to be said that when I replaced the turbo in
the plastic rocket it only cost me 300 notes for a recon job, and that
was a full replacement as mine was so old and badly looked after, it
would have been less if the car's previous owners had looked after it
more.

--
For every expert, there is an equal but opposite expert
 

"Jon" <[email protected]> wrote in message
news:eek:[email protected]...
> So...
>
> Picking the bones out of all your replies I have come up
> with this:
>
> 1. Perhaps the "little rubber thingy" isnt a dump valve
> after all.
>
> 2. If you DO NOT have a snorkel leave the "little rubber
> thingy" so
> that any water and muddy **** can theoretically run away
> once it finds
> its way into the air cleaner casing.
>
> 3. If you DO have a snorkel remove said "little rubber
> thingy" and
> fill the remaining void with silicone as it serves no
> point other than
> above.
>
> Cool. Job done.
>
> Jon
>
>
>
> On Fri, 15 Apr 2005 13:42:47 +0100, Jon
> <[email protected]> wrote:
>
>>Just a quick question...
>>
>>I'm setting about extending breathers up the snorkel and
>>sealing up
>>the airbox etc and came to the dump valve - whch set me
>>thinking.
>>
>>What is the point of this silly bit of rubber?? When the
>>turbo is
>>sucking air the valve 'closes' and pulls air from the air
>>inlet
>>(snorkel) and when you lift off and get back pressure to
>>the turbo the
>>excess pressure can release through the snorkel that is
>>not 3 feet
>>away?
>>
>>So can I just seal it up so I havent got one anymore or am
>>I missing
>>something fundemetal in my thinking.
>>
>>Whilst I'm on this subject, mine isnt really that clever
>>at sealing
>>itself under vaccum anyway - should I replace it or just
>>seal it up?
>>
>>Any thoughts or advice welcomed.
>>
>>Thanks
>>Jon
>

Ok,

So in another context (not the rubber thingy) what would a
dump valve be?

Thick 90 owner in Norfolk....

Regards

Richard


 
Richard wrote:

> Ok,
>
> So in another context (not the rubber thingy) what would a
> dump valve be?
>

Waste gate on the turbo I'd guess.

P.
--
1992 200 TDI Disco - heavily modified
1982 V8 Range Rover - heavily corroded
2000 Rover 75 - heavily driven
1993 Lexus LS400 - just plain heavy on fuel
 
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