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Diesel Return (leak off) pipes |
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madra 
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Lorem ipsum Joined: 25 Jan 09 Location: bollox Status: Offline Points: 957 |
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 Posted: 14 Apr 09 at 22:07 |
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i just got clobbered with a leaking return pipe on the day i was due to come back from my easter weekend jaunt to angelsey. luckily i had some rubber tube in my toolbox, so was able to replace the perished section and got herman home without further probs.
i'm still a bit confused tho' - i thought the return pipes just gravity fed back into the main fuel pipe that runs back to the tank and that only the 'input' side of the fuel system was pressurised and needed to be scrupulously airtight. yet, with my return pipe leaking, there were shitloads of air bubbles in the pump intake pipe. how does a leak in the return side cause air in the intake side? the entire fuel system cannae be airtight, as otherwise you wouldnae be able to remove the fuel filler cap without 'breaking the seal'  |
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markpark
Vanorak 
Joined: 18 Aug 06 Location: Leeds Status: Offline Points: 1364 |
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Posted: 14 Apr 09 at 22:46 |
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But if you remove the filler cap the fuel pickup if immersed in liqiuid so air shouldn't get in. I wouldn't have thought air could go backwards through the injectors through the injection pipe through the pump which is full of fuel and into the intake pipe.
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DJ T3 homrbrew camper and 98 LT 2.5 TDI crew van
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mike38
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Joined: 12 Jul 04 Location: United Kingdom Status: Offline Points: 609 |
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Posted: 15 Apr 09 at 00:51 |
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Can it be that the return pipe goes back to the filter first into that valve thinghy so air is getting sucked into the system via the valve thing direct into the filter? i have fitted a normal filter without the valve thing and my return goes back to the tank ive seen no air bubbles when my returns where pissing diesel all over and had no starting or running problems?
Mike |
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madra
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Lorem ipsum Joined: 25 Jan 09 Location: bollox Status: Offline Points: 957 |
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Posted: 15 Apr 09 at 09:34 |
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it looks like the return pipes from the injectors just drain back into the main fuel tank return pipe. on mine, they join up to it at a point which is already beyond the fuel filter on the return side. which is why i cannae understand how any bubbles there would still be around by the time that the fuel had recirculated right round the system back to the injector pump again.
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thal
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Joined: 29 Apr 08 Location: Bolton Status: Offline Points: 514 |
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Posted: 16 Apr 09 at 09:27 |
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Because the fuel pipes etc are lower than the injectors fuel syphons back when not been driven by the pump so if you have a leaking pipe it sucks air back into the system. Cure! add a none return valve to stop syphoning.
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2.4 td high top home conversion And2.4td LWB high top van
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madra
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Lorem ipsum Joined: 25 Jan 09 Location: bollox Status: Offline Points: 957 |
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Posted: 16 Apr 09 at 09:43 |
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ah - well thought out. that makes sense.
  anyway, at some stage i am planning to replace all my botched together piping in and around the fuel filter and injector pump, so i'll likely fit a non-return valve then. anyone know what diameter the various fuel piping is? there are at least two sizes; the thicker stuff going from the filter to the injector pump and then thinner stuff on the return pipes. then there's the main fuel pipes to and from the tank, which [from memory] i think might be thicker again. i've had that many probs with air in mine that i feel like ripping the whole lot out and plumbing it all in afresh. also, when i had to replace the perished section of run-off pipe at the weekend [it was the bit nearest the filter], i noticed that where it rejoins the main fuel line back to the tank, there is a T-connector there, which is made of plastic. i'd like to replace that with a metal one. i dinnae trust plastic connectors, as you cannae tighten anything onto them as much as you'd like, for fear of snapping off the end. |
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icky
Vanorak
Joined: 01 Jun 06 Location: Windlesham Status: Offline Points: 1424 |
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Posted: 16 Apr 09 at 12:11 |
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which is why you don't fuck about with live injectors, because they will quite happily inject fuel straight through your skin and directly into your veins from a distance of up to a couple of meters!
 hooray for instant death.the other thing about return pipes is that in a lot of cases, the entire system is very slightly pressurised (though not to the extent of the pump>injector system). hence it won't work if theres a break anywhere in the system... including taking the fuel cap off
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niko
Vanorak
Nice fella. Joined: 01 Jul 07 Location: Stroke On Tent Status: Offline Points: 2639 |
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Posted: 18 Apr 09 at 20:35 |
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i have just had a set of injector pipes made up at a local diesel enginner specialist ...12 quidd a go...copied from my originals. fitte dlast night and spot on.
also got some new leak off tube at 4.00 meter...mine had perished and wer leaking air bubbles back to the filter.
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mike38
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Joined: 12 Jul 04 Location: United Kingdom Status: Offline Points: 609 |
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Posted: 22 Apr 09 at 23:16 |
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Mines still ok done a fair few miles since soldering it got a second hand set off flebay 99p so will be fitting it soon and keeping the rest as spares.
Mike |
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paulj
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Joined: 27 Jul 08 Location: North Wales Status: Offline Points: 463 |
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Posted: 26 Apr 09 at 11:03 |
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I was responsible for the diesel assembly line in Deeside (Toyota) for the three years we assembled the 2.0l common rail diesel engine. The health risks of fuel injected diesel are very serious (though not necessarily instant death!) - basically fuel injected doesn't necessarily hurt at the time, but the only way of cleaning the fuel back out is to slice the offending area open, and to strip the diesel out. Amputation is apparently often the only solution. When testing the fuel system (every engine is run before shipping to vehicle plant) we made a simple cover from perspex to cover the fuel rail, injectors and injectors pipes. We also made a safety card so in the event of having to transfer someone to hospital they would take the card with them to explain the problem to the medical staff. We never needed to use it. Diesel is generally bad for ths skin as well, so I would recommend rubber gloves if working with the fuel system. The latest fuel rail systems with piezo injectors can reach over 2000 bar, and the injector is opened and closed several times during the combustion cycle! /Anorak mode off  |
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minilandrover
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Joined: 07 May 09 Status: Offline Points: 1 |
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Posted: 07 May 09 at 08:36 |
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 hello guys, and gals, ive been reading about diesel return pipes, ( cos ive got an air leak on my Ahem opel...) anyway when i see you all going on about the cost of these usless rubber ones that perrish i just had to sign in and comment. 
Nobody seems to have tried using straight forward SILICON TUBING, available from any model store or fish tank store. i have meters of the stuff in bright floresent green, (easy to find in the toolbox) I renew my supply everytime i return to the uk. i used it primarily on my model submarines (stick with it i will get there) as i needed a flexible non perishing tubing that can take up to 2-3 bars pressure. resilliant to heat, vibration, acid, water, oil, petrol and i hope diesel.
 Good for almost everything, i use it for a great variety of things and im about to cut a set to replace the returm pipes on my diesel opel. when the fuel tank is below half, starting gets longer, taking time to pump out the air that has seeped in through the leaky pipes, that are always wet and giving the engine compartement a nice diesel smell! Silicon tubing costs about 50 pence to a quid per meter, depending on wher you get it. it is thick walled but stretches to go over the nipples on the injectors or what ever you put it over. only warning is to insure that when you cut the tubing you make a nice clean cut with a straight edge. push on gently with fingers not pliers as it is easy to cause compression splits. then you will be back to leaking pipes again! they are easy to push on and will take a lot to pull off as when you pull on it, it will stretch and try to get thinner and tighten up on the nipple. Anyway there it is a cheap and reliable cure, looks pretty too... |
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no body does it better than if i do it my self, and iv'e only got my self to blame!
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huwi
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Joined: 17 May 10 Location: cambridge Status: Offline Points: 1 |
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Posted: 17 May 10 at 20:09 |
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hi
from my experience silicon pipe expands & go soft in contact with kerosene/paraffin [as used in model diesel engines] & I think that diesel will do the same clear PVC pipe is good but hardens in time so whilst fitted is fine, until you remove & try to refit |
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t'onion
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Joined: 12 May 05 Location: Sheffield Status: Offline Points: 1419 |
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Posted: 17 May 10 at 20:28 |
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the end blank went on mine while away , kept saying to the missus 'can you smell diesel ?' I whipped the lid off to find diesel pissing out of the blank , A mate had a spare (luckery) , but when i was doing the glow plugs at the weekend I noticed it looking a wee bit cracked , so going to get a few new ones and fit a new one before we head out in it again .
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LT28 Westfalia FloRida, 2.4 diesel
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madra
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Lorem ipsum Joined: 25 Jan 09 Location: bollox Status: Offline Points: 957 |
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Posted: 18 May 10 at 08:27 |
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exactly what happened to mine. i spent £30-odd a while back buying a couple of rolls of [allegedly] made for purpose fuel line from these guys and i've had to replace leak-off pipes at annoyingly regular intervals ever since. as huwi says, it softens up and loosens through time and then starts leaking again. complete waste of money!
i've given up on the 'proper' pipe and gone down the PVC route now myself; about a quid a metre from B&Q. the smallest one they do [i think it's 3mm inner diameter] fits on the leak-off nipples as tight as the proverbial duck's arse. in fact it was such a tight fit, i had to boil the tube first to get it over the nipples. but, provided the diesel disnae dissolve it, i reckon those leak-off pipes are on for good now. |
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rainbow1969
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Joined: 04 Feb 09 Status: Offline Points: 16 |
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Posted: 02 Sep 10 at 20:07 |
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i have owned a lt45 2.4 diesel for 2 years and it has had one of the injector pipes soldered before it came to me and is fine never had any probs!
The reason i followed this thread was cos the final blank stopper on the end injector on mine keeps blowin off makin a mess of diesel all over the place and i wondered if this was a well known prob!! i replace it and it only seems to last a few months but like was suggested maybe thats crap quality of parts was thinkin of doin something more secure to keep it on but concerned it is meant to be like a safety blow off thing and i could do some damage  so any thoughts guys most appreciated............ |
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rainbow1969
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Joined: 04 Feb 09 Status: Offline Points: 16 |
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Posted: 02 Sep 10 at 20:08 |
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i have a lt45 2.4 diesel it has soldered injector pipe which was done in a previuos life still goin strong and ive owned it 2 years!
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