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Filling the expansion tank?

muddyboots

Still hanging around
Oct 16, 2002
5,739
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Originally posted by prc
It's usually located at about (09:00).
On Mk4 Ibiza TDIs, it's at 3 o'clock (ie on the right as you're stood looking at the filler neck). Just try and nudge it in towards the car, and keep on filling. But like prc says, do it slowly, and keep a close eye one the rising fuel - otherwise you'll get diesel all down yer leg before the pump cuts off :D
When I fill mine like this I can almost reach 200 miles before the needle moves off the top of the gauge.
 

cheshire cat

Full Member
Dec 28, 2002
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cheshire
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better still

better still give it a ventectomy, takes about five minutes and you need a small torx driver, details on Fred's Tdi -search for ventectomy. Five hundred miles per tank no trouble.
 

slim_boy_fat

Guest
Its amazing when i fill up i can get about 50 liters in, and thats with about 5-8 liters left in the tank. So there must be about 10liters min available through venting.

Whats this ventectomy thing, is it a way of bypassing it?
 

Jon TDI

Eat My Soot!!
Apr 28, 2003
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Round the twist.
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i can only eek out 480 and thats doing about 57mpg on a 480 mile one day run, suppose i could run it on the buzzer for longer and maybe just about eek out 500!

That's what I do. When I come to fill it up again it takes around 43-44 litres. Buzzer means you still have about 7 litres left, but it's bloody annoying every time you switch the ignition on!
 

slim_boy_fat

Guest
I got 750 out of my wifes golf.... Running on vapour at the end i think.
 

sssstew

Editing your spelling
ahh cool ok, will have to run mine on buzzer for longer.... my friends parents used to do silly miles on the buzzer, we would get in to go some where and we would say best fill up and his dad would say 'nah we will be fine' always shocked me how far we would go:)
 

prc

Sooty Meister
Re: better still

Originally posted by cheshire cat
better still give it a ventectomy, takes about five minutes and you need a small torx driver, details on Fred's Tdi -search for ventectomy. Five hundred miles per tank no trouble.

Not sure this is a very good ideas, especially in warmer climates and/or filling it up just before parking it in the driveway.
 

aceman

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May 6, 2002
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West Yorkshire
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If you fill up until the nozzle clicks off and then depress the little lever on the right hand side of the filler with the nozzle you will be able to hear a hissing sound. This is the air trapped in the top of the tank being released. If you continue to hold the lever in I can get on average an extra £7-8 quid in which accounts for about 10 litres. Mind you as Paulo states be wary of not over doing it as the system is actually designed to deliberatly stop you filling all the way up so as to allow the fuel to expand in the tank particulary in warm weather but as our climate is changing for the cooler this should not present too much of a problem for a while.
 

cheshire cat

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Dec 28, 2002
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cheshire
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ventectomy

is basically removing the little black valve and it's spring, takes five minutes, tested in the worst of American heat, no problems all this summer over here and at last fill 517 miles @ approx52+mpg to the buzzer even tho' there is a healthy reserve.
 

prc

Sooty Meister
Re: ventectomy

Originally posted by cheshire cat
is basically removing the little black valve and it's spring, takes five minutes, tested in the worst of American heat, no problems all this summer over here and at last fill 517 miles @ approx52+mpg to the buzzer even tho' there is a healthy reserve.

It depends how much extra you put in. If you fill it up til the top then it will leak. If you just add an extra 8-10L you probably will not have a problem.
I think that petrol expands more than diesel anyway.
 

prc

Sooty Meister
Sort of an off topic:

Was talking to a couple of the Bosch guy regarding alot of diesel pump problems that have been happening as of late. I was told to be very careful with the amount of fuel in the tank, and to fill up as quickly as possible after the buzzer (reserve). Seems that since the pump works with very high pressures, it uses the fuel in tank as a cooler.
 

cheshire cat

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Dec 28, 2002
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cheshire
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cooler fueller

This is a fair point, I assume that the pump (PD) is constant volume and therefore returns the surplus to either the filter, if cold or the tank when hot , via what I assume is the fuel cooler under the drivers side floor. The less fuel used and the hotter the weather the more churn and more cooling needed. There is obviously a large fuel temp gradient allowed for as volume is adjusted in relation to fuel temp(Foxy Mod) I hope that you Seat techs' will jump in and correct or expand any of this. I can say that on the hottest day we hade recently (28+C) on filling my ventectomied tank I could see hot vapour or steam coming out of the top right hand vent having just done several slow miles on a low tank (no light on) Am I right in thinking the valve on the fuel filter top is temp controled or is that done somewhere else. Hope I havn't hijacked the thread. :cheers:
 

Fl@pper

Back older greyer and less oilier but always hope
Jun 19, 2001
12,368
25
Gloucester
i found the wiring for the external buzzer last night :):)

where's my cutters gone
 

muddyboots

Still hanging around
Oct 16, 2002
5,739
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Slightly off topic, but related to fuel...
What would be the implications of running out of diesel?
Would it eventually start again after a refil, or would you have to mess about disconnecting pipes and priming etc ? I remember my dad running his Pug 305 van dry, and having to loosen some of the injector pipes to bleed air out while cranking the starter. Wouldn't fancy having to do that with the kind of fuel pressure PDs generate....
 
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