paulgato
Member
That was easy!
Been thinking of doing this on my 2002 Golf TDi PD for a little while but the need(?)to check the accuracy of the MPG display convinced me to do it today.
(In fact I'm shortly going to get an engine re-map done - for extra fuel efficiency rather than extra power - and I've heard that after a re-map the MPG meter can become 'differently accurate', so I want to get an accurate idea of the actual fuel efficiency before the re-map so I can tell if the re-map is making the car more fuel-efficient or not. The re-mapping company give a 14 day money-back guarantee and a return to your original settings if not satisfied, but I don't want to be fooled by an innacurate trip computer into thinking the MPG has gone up. HENCE the 'need' to get rid of the 'vent' so I can fill up to the same level every time.
(BTW, the term, 'ventectomy' is really a misnomer. You are not taking out a vent; you are taking out the spring-loaded valve mechanism which CLOSES the vent when the filler cap is removed for re-fueling. The closing of that vent traps about ten litres of air at the very top of the tank, limiting the amount of fuel that can be put in there by about the same amount. Whether this 'ventectomy' has been carried out or not make no difference once the filler cap is back in place. The vent is always open then.
So, since I've just done it, I thought I'd give some clues to any others reading this.
Firstly, how to do it. These pics are excellent, and following them was easy...
http://pics2.tdiclub.com/gwillie/VW/ventectomy/
It was all very straightforward except for sliding the the white plastic cartridge out of the black plastic housing. That was hard. I would not have been able to do it by pushing it out with my fingers alone. Pushing the clip up was easy but the cartridge itself was a stiff fit in the housing. I took it carefully and used a mirror to see what was what in there. In the end I had success with a pair of side grips that allowed me to press on the round nozzle-shaped lever (the lever you would push inwards to vent the tank normally). Gentle pressure with the side grips while freeing the clip on the white plastic cartridge did the trick. Removing the nozzle-shaped lever from the cartridge and reassembling everything was very easy. In all it took me half an hour.
Secondly, to answer some in this thread who asked, "Why do it...?"
Well, the usual reason is to increase the capacity of the tank to increase range between fill-ups. Not an issue for me exactly but if you live 50 miles from the nearest petrol station then that would decrease the liklihood of having to make a special journey just to fill up, rather than being able to combine it with a grocery shop or whatever. My reason for doing it is different and specific and is stated above.
And thirdly, is is safe...?
Having read around the subject on and off for a few months I have not heard of one single person who has had a problem with it, in any climate. It is totally legitimate to ask how it can be safe to circumvent the manufacturer's 'safety system' in this way, but I consider it to be totally safe in this case (for diesels!) and let me explain why...
The worry some people express is that as the temperature rises the fuel will expand and spill out of the tank onto the road, possibly causing a motorcyclist to skid off the road on a bend and die. This expansion could theoretically happen either because the ambient temperature is higher than the temperature of the fuel as it goes into the tank, or because of the fact that the engine returns warm fuel back to the tank, gradually warming the whole tank. This is a legitimate concern of course, but since not one single person has reported any fuel spillage happening, and plenty of people have reported there being no problem, even those living in seriously hot climates, I'm not going to worry. Others have explained why this would not happen. I don't know enough to say why it doesn't but if it did ever happen I'm certain someone would have mentioned it, and nobody has.
As for why VW would put this feature (the ten litre air gap at the top of the tank) in the car for no reason, well, errm, I guess it's for the same reason that God gave men nipples. It's because there's no great reason not to. The vent (this is really a misnomer - the vent is still going to be there even after this procedure, so let me re-phrase...) The 10 litre air gap at the top of the tank is ABSOLUTELY NECESSARY FOR A PETROL (GASOLINE) VEHICLE, and does NO HARM in a diesel vehicle, so it is easier to make just one kind of fuel tank and use it for both types of vehicle, rather than making specific diesel fuel tank assemblies.
OK, that's my opinion. I'm no expert but having looked into it quite thoroughly, that's what I think.
Been thinking of doing this on my 2002 Golf TDi PD for a little while but the need(?)to check the accuracy of the MPG display convinced me to do it today.
(In fact I'm shortly going to get an engine re-map done - for extra fuel efficiency rather than extra power - and I've heard that after a re-map the MPG meter can become 'differently accurate', so I want to get an accurate idea of the actual fuel efficiency before the re-map so I can tell if the re-map is making the car more fuel-efficient or not. The re-mapping company give a 14 day money-back guarantee and a return to your original settings if not satisfied, but I don't want to be fooled by an innacurate trip computer into thinking the MPG has gone up. HENCE the 'need' to get rid of the 'vent' so I can fill up to the same level every time.
(BTW, the term, 'ventectomy' is really a misnomer. You are not taking out a vent; you are taking out the spring-loaded valve mechanism which CLOSES the vent when the filler cap is removed for re-fueling. The closing of that vent traps about ten litres of air at the very top of the tank, limiting the amount of fuel that can be put in there by about the same amount. Whether this 'ventectomy' has been carried out or not make no difference once the filler cap is back in place. The vent is always open then.
So, since I've just done it, I thought I'd give some clues to any others reading this.
Firstly, how to do it. These pics are excellent, and following them was easy...
http://pics2.tdiclub.com/gwillie/VW/ventectomy/
It was all very straightforward except for sliding the the white plastic cartridge out of the black plastic housing. That was hard. I would not have been able to do it by pushing it out with my fingers alone. Pushing the clip up was easy but the cartridge itself was a stiff fit in the housing. I took it carefully and used a mirror to see what was what in there. In the end I had success with a pair of side grips that allowed me to press on the round nozzle-shaped lever (the lever you would push inwards to vent the tank normally). Gentle pressure with the side grips while freeing the clip on the white plastic cartridge did the trick. Removing the nozzle-shaped lever from the cartridge and reassembling everything was very easy. In all it took me half an hour.
Secondly, to answer some in this thread who asked, "Why do it...?"
Well, the usual reason is to increase the capacity of the tank to increase range between fill-ups. Not an issue for me exactly but if you live 50 miles from the nearest petrol station then that would decrease the liklihood of having to make a special journey just to fill up, rather than being able to combine it with a grocery shop or whatever. My reason for doing it is different and specific and is stated above.
And thirdly, is is safe...?
Having read around the subject on and off for a few months I have not heard of one single person who has had a problem with it, in any climate. It is totally legitimate to ask how it can be safe to circumvent the manufacturer's 'safety system' in this way, but I consider it to be totally safe in this case (for diesels!) and let me explain why...
The worry some people express is that as the temperature rises the fuel will expand and spill out of the tank onto the road, possibly causing a motorcyclist to skid off the road on a bend and die. This expansion could theoretically happen either because the ambient temperature is higher than the temperature of the fuel as it goes into the tank, or because of the fact that the engine returns warm fuel back to the tank, gradually warming the whole tank. This is a legitimate concern of course, but since not one single person has reported any fuel spillage happening, and plenty of people have reported there being no problem, even those living in seriously hot climates, I'm not going to worry. Others have explained why this would not happen. I don't know enough to say why it doesn't but if it did ever happen I'm certain someone would have mentioned it, and nobody has.
As for why VW would put this feature (the ten litre air gap at the top of the tank) in the car for no reason, well, errm, I guess it's for the same reason that God gave men nipples. It's because there's no great reason not to. The vent (this is really a misnomer - the vent is still going to be there even after this procedure, so let me re-phrase...) The 10 litre air gap at the top of the tank is ABSOLUTELY NECESSARY FOR A PETROL (GASOLINE) VEHICLE, and does NO HARM in a diesel vehicle, so it is easier to make just one kind of fuel tank and use it for both types of vehicle, rather than making specific diesel fuel tank assemblies.
OK, that's my opinion. I'm no expert but having looked into it quite thoroughly, that's what I think.
