 | Home > Puma (Tdci) > fuel breather pipe |
 
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| ericvv Member Since: 02 Jun 2011 Location: Near the Jet d'Eau Posts: 5816   
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Thanks for that info. 0.13 bar, or in the other direction 0.04 bar sounds as very small, and should not mean that there should be a real air hissing sound from equalizing pressure when opening the fuel cap.
So what do I make of this? Is my fuel cap valve broken, and can the problem be resolved by merely replacing the fuel cap by a new one? But if that would be the issue, what is the function of that little air breather pipe which has been teed into the filler breather? Is this little air breather pipe possibly supposed to do the job of equalizing air pressure at all times, and is the valve in the fuel cap a secondary air equalizer only? basically as a safety net in case the little air breather pipe gets blocked? (= as someone said earlier in this thread) So if that would be all true then it seems that I have both the primary air breather (the little pipe) as well as the secondary air breather (valve in the fuel cap) broken.  You never actually own a Defender. You merely look after it for the next generation.
http://youtu.be/yVRlSsJwD0o https://youtu.be/vmPr3oTHndg https://www.youtube.com/watch?v=_GtzTT9Pdl0 https://www.youtube.com/watch?v=ABqKPz28e6A https://www.youtube.com/watch?v=rLZ49Jce_n0 https://www.youtube.com/watch?v=XvAsz_ilQYU https://www.youtube.com/watch?v=K8tMHiX9lSw https://m.youtube.com/watch?v=dxwjPuHIV7I https://vimeo.com/201482507 https://www.youtube.com/watch?v=ZSixqL0iyHw |
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1st Jan 2014 9:24pm |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558 
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half full tank so roughly at a guess 30lt air space pressurised to 1or 2 psi is going to make a fair hissing noise
mine has the small breather pipe on other side of tank and I changed the pipe ( because it was starting to crack ) and the small valve in the pipe I could blow through it but not really suck though it and to double check it was right I got one out of stock and was the same , so refitted mine but put a filter on pipe to stop it sucking dirt in . |
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1st Jan 2014 9:41pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17382  
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As stated (several times now) earlier in this thread, and as made clear in the workshop manual, there is a bidirectional pressure relief valve in the filler cap which is provided solely for protection in the event that the atmospheric breather becomes blocked.
If the relief valve was not provided and the breather became blocked, eventually as the engine draws fuel from the tank the plastic tank will collapse (many years ago I had this happen to the metal tank on an HGV I was driving when the breather became blocked. It's quite spectacular!) There is also a real risk of the tank bursting if it heats up. This is the sole reason for the valve in the cap, and under normal correct operating conditions the tank will always be at atmospheric pressure. One of the service bulletins concerned with fuel contamination specifically mentions this since the genius design of the system means that if the relief valve in the cap is called upon to admit air into the tank it draws the air through the lock barrel in the cap and ingests any dirt and crud from the lock into the fuel tank. The bulletin cites this as an identified cause of contamination. When I was purging my fuel lines the operatoon of the relief valve was very easily confirmed since I was using the modified atmospheric breather, which I have routed into the rear buck and had temporarily fitted with a Schrader valve, to pressurise the tank. The valve in the cap could be heard to open to limit the pressure in the tank. Thinking more about the modified breather on the later vehicles, I am forced to the conclusion that the ROV (see my previous post) must have been deleted, unless it is somehow incorporated into the breather filter (which seems unlikely since the latter looks exactly the same as before). The reason for this conclusion is that with the new breather, if the vehicle rolled, fuel would flow up the filler pipe, then down the filler breather to the atmospheric breather, and escape. Perhaps LR decided that if you have rolled, a leak from a small breather isn't a significant problem! Eric, I am convinced that you don't have a faulty cap (your tank would by now have imploded if you did) and that you have a second defective breather. If I were you, I would fit an extension to the breather not only to route it to somewhere clean and dry but also to somewhere where I could blow down it to confirm it isn't blocked or to bleed the fuel system if necessary. I appreciate however that you may prefer to keep it standard and get the dealer to sort it out properly the way it should have been in the first place! |
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1st Jan 2014 10:55pm |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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if the cap has pressure relief at 1.8-2.0 psi and the small breather pipe has a valve you can blow though ( to allow for fuel being used ) but not suck so . surely that means you could get slight pressure build up in tank and I mean slight because the average person can blow 3 psi with there mouth . so not enough to do any damage to tank
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1st Jan 2014 11:19pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17382
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As far as I know the little breather has a filter, not a valve. I could blow and suck through mine (although neither was pleasant).
If I can find it, since I took it off the vehicle, I will dissect the blob and see what's inside. The full description of the fuel breather system in the WSM makes no mention whatsoever of a valve in this pipe, only the ROV in the tank, and a valve makes no technical or engineering sense and would serve no purpose. Perhaps you weren't blowing or sucking hard enough! |
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1st Jan 2014 11:44pm |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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think they is valve in there not a filter ..I would think a filter that size would block to quick
if it was a filter surely they would fit a normal inline fuel fuel .. they used them on some vacuum systems to stop crap getting in and inline filter is clear so you could see how dirty it was most aftermarket breather valves has 2valves one with steel ball and one plastic ball so it floats to stop fuel being pushed out if overfilled also just remembered the valve has a direction arrow on it so can't be just a filter think you can blow and suck though them but harder one way than the other and the one I got out to check was the same thinking about it would it not make sense to have the cap venting out ( for temprature expansion ) because it's allways going to be higher than fuel level and small pipe venting in to allow for fuel used but in land rover wisdom they fitted it under the arch but moved it on later models |
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1st Jan 2014 11:51pm |
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| ericvv Member Since: 02 Jun 2011 Location: Near the Jet d'Eau Posts: 5816
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Gents, thanks for your extensive comments. As said, dealer will be informed of this today, and they already received the thread to this topic by e-mail, so they can read up all this.
I can only think that there is something faulty with this new breather pipe which they installed, but it is up to them to correct this, (which no doubt they will do without a problem). Will kepos, but it may take a bit as I don't know when they will have time and place to take in the truck. In the meantime, it stays put. Eric You never actually own a Defender. You merely look after it for the next generation. http://youtu.be/yVRlSsJwD0o https://youtu.be/vmPr3oTHndg https://www.youtube.com/watch?v=_GtzTT9Pdl0 https://www.youtube.com/watch?v=ABqKPz28e6A https://www.youtube.com/watch?v=rLZ49Jce_n0 https://www.youtube.com/watch?v=XvAsz_ilQYU https://www.youtube.com/watch?v=K8tMHiX9lSw https://m.youtube.com/watch?v=dxwjPuHIV7I https://vimeo.com/201482507 https://www.youtube.com/watch?v=ZSixqL0iyHw |
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2nd Jan 2014 4:59am |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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from workshop manual :
The atmospheric vent pipe includes a two-way valve which allows for over-pressure relief one way and allows for air to enter the tank as the system operates in depression. so small breather pipe has valve that lets air in easier than out .. so I would say that means it could build up a small pressure |
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2nd Jan 2014 9:31am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17382
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Good find! You must have a later manual than me!
If I can find my removed pipe I'll dissect it. |
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2nd Jan 2014 10:21am |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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just got other valve out and if you suck or blow it is easier one way then the other ..
I read the bit in manual about 3 times before I see that bit!!! |
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2nd Jan 2014 10:27am |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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was your tank low on fuel when its makes hissing noise or does it do it all the time .. I think it would only do it if you took cap off quickly after stopping if left for a while I think it would not hiss think it would do it more if tank low as more air space to expand as tank warms up after running. |
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2nd Jan 2014 10:32am |
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| ericvv Member Since: 02 Jun 2011 Location: Near the Jet d'Eau Posts: 5816
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Tank has been around 3/4 full of late. The hissing sound has been happening also when taking off the fuel tank cap after the truck has been parked up for several days. So something is fully blocked there, air can not get in or out even slowly.
Tuesday I have parked up the truck at my office parking lot, but I vented the tank still before driving there from home (less than 10 miles). The air temp outside has been low, around 0°C, and in our office parking it must be abt 20°C. This morning I went down to the truck and took took the fuel cap off, and a big hissing sound accompanied by a distinct diesel smell as result. So the air in the tank must have expanded with the air temp, and created high pressure diesel fumes which could not be released during all of the 2 days it has been in the parking.... Dealer is only back open after the holidays on monday. Will see then with them. Eric You never actually own a Defender. You merely look after it for the next generation. http://youtu.be/yVRlSsJwD0o https://youtu.be/vmPr3oTHndg https://www.youtube.com/watch?v=_GtzTT9Pdl0 https://www.youtube.com/watch?v=ABqKPz28e6A https://www.youtube.com/watch?v=rLZ49Jce_n0 https://www.youtube.com/watch?v=XvAsz_ilQYU https://www.youtube.com/watch?v=K8tMHiX9lSw https://m.youtube.com/watch?v=dxwjPuHIV7I https://vimeo.com/201482507 https://www.youtube.com/watch?v=ZSixqL0iyHw |
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2nd Jan 2014 12:38pm |
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| ericvv Member Since: 02 Jun 2011 Location: Near the Jet d'Eau Posts: 5816
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Reviving this thread as the issue is not resolved yet. Most likely (and hopefully) will be resolved with my dealer having ordered an entirely new breather pipe which will be installed next week.
The situation up to now is that after my dealers initially replaced the cracking breather pipe by an entirely new one back in September, it appeared that the new one did not do its job of venting the air under- or overpressure in the fuel tank. Two times thereafter my dealer have again lowered the fuel tank and tried to correct the problem. At their second attempt they determined that the bidirectional air valve in the coat hanger shaped hard plastic air venting pipe apparently was faulty as they tested it with compressed air, and it did not work. This air valve seems a common part in many LR/RR models, so they replaced that little valve by another one they had in stock. Surprisingly still not solved. So they now decided to order an entire new fuel tank breather pipe, which was not in stock at LR Switzerland, and will arrive beginning next week from the UK. What is the most surprising to me is the following. About 10 days ago I drove the truck from home to my underground office parking. That means that from an ambient temp of around 0°C outside at home, it went to roughly an ambient temp of a constant 18°C. When I parked the car there on a sunday, I still opened the fuel tank cap, and heard a minor air swoosh of air getting into the tank. On monday, I went down, and again unscrewed the fuel cap, and got a big swoosh of air/diesel fumes escaping from the tank, so there was an overpressure created while it was parked there, which probably has to do with the fuel warming up from 0 to 18°C. Ok sofar, but the air breather surely does not work. More surprisingly, again two days later and the car having not moved at all, I again unscrewed the fuel cap, and yes, again a rather big volume of air/diesel fumes escaping from the tank. Here I can not follow anymore, I first equalized the pressure, and then there seems again an overpressure developping for no reason at all. (No car movement, no change in ambient temp, etc.) What does this mean? Is it so that at normal room temperature diesel in the tank slowly evaporates and creates fuel fumes/overpressure which then escapes via the airvalve in the (working) air breather pipe? Have no other explanation than that this must be so. Anyone in the know about this? Tks, Eric You never actually own a Defender. You merely look after it for the next generation. http://youtu.be/yVRlSsJwD0o https://youtu.be/vmPr3oTHndg https://www.youtube.com/watch?v=_GtzTT9Pdl0 https://www.youtube.com/watch?v=ABqKPz28e6A https://www.youtube.com/watch?v=rLZ49Jce_n0 https://www.youtube.com/watch?v=XvAsz_ilQYU https://www.youtube.com/watch?v=K8tMHiX9lSw https://m.youtube.com/watch?v=dxwjPuHIV7I https://vimeo.com/201482507 https://www.youtube.com/watch?v=ZSixqL0iyHw |
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19th Jan 2014 11:42am |
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| ericvv Member Since: 02 Jun 2011 Location: Near the Jet d'Eau Posts: 5816
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So my dealer installed last thursday and entire new fuel breather pipe, including the hard plastic coat hanger air venting pipe with that air valve we can see in the posted pictures. Contrary to what I said before it appears that this air breather valve is unidirectional, only lets air into the tank as fuel gets consumed and a vacuum starts to develop.
As I also had an issue with overpressure devellopping in the tank when the truck went from a cold environment into warmer ambient temps like when parking it up in my underground office parking, the dealer also replaced the fuel cap by a new one. Apparently the fuel cap has a bi-directional valve to equalize air pressure, and works as a secondary valve to compensate a vacuum in the tank, but the cap is the only valve which releases air (diesel fumes) from the tank in case of over pressure.... So now I have an unasked for upgrade in the form of a Puma 2.2 fuel cap with the little plastic leash in order to not loose the cap when filling up.  
First tests show that no more vacuum devellops in the tank as fuel gets used..... So hopefully after several interventions by the dealer to get this all righted it looks like it got finally solved.  Will watch it a bit longer though. Must say my dealer has been very good at all this, each time they had to lower the fuel tank to get access, never said "but they all do that sir", etc...
Eric You never actually own a Defender. You merely look after it for the next generation. http://youtu.be/yVRlSsJwD0o https://youtu.be/vmPr3oTHndg https://www.youtube.com/watch?v=_GtzTT9Pdl0 https://www.youtube.com/watch?v=ABqKPz28e6A https://www.youtube.com/watch?v=rLZ49Jce_n0 https://www.youtube.com/watch?v=XvAsz_ilQYU https://www.youtube.com/watch?v=K8tMHiX9lSw https://m.youtube.com/watch?v=dxwjPuHIV7I https://vimeo.com/201482507 https://www.youtube.com/watch?v=ZSixqL0iyHw |
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26th Jan 2014 6:06pm |
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