ejparrott Posted August 21, 2012 Share Posted August 21, 2012 If you tank gaskets are all in good nick as they should be, then put a pipe between the top of each tank, T'd to the return line. Then when one tank is full to the brim, it'll go across to the other instead. It can't work it's way up the filler necks, unless both tanks are brimmed. Gravity tends to level fluids. Quote Link to comment Share on other sites More sharing options...
mikey7134 Posted August 21, 2012 Author Share Posted August 21, 2012 Is it worth just choppin the whole battery tray out while I'm at it? I can find somewhere for the battery other than the tray, so need I leave any of it? Quote Link to comment Share on other sites More sharing options...
mikey7134 Posted August 21, 2012 Author Share Posted August 21, 2012 If you tank gaskets are all in good nick as they should be, then put a pipe between the top of each tank, T'd to the return line. Then when one tank is full to the brim, it'll go across to the other instead. It can't work it's way up the filler necks, unless both tanks are brimmed. Gravity tends to level fluids. Tanks aren't by any stretch New, so there's always the risk of getting a partial, at least, bloackage in a line and over flowing. Also, I don't know the reasoning for it, but I've been told on a couple occasions not to fill fuel tanks to the brim. Possible a vacuum thing?!? Cheers. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted August 21, 2012 Share Posted August 21, 2012 I do, I fill them right up the neck to the cap just before we leave on holidays, that way I can calculate fuel consumption on our return by filling it all the way up to the brim again. Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted August 21, 2012 Share Posted August 21, 2012 Apparently, your not supposed to fill them to the brim to allow ample space for expansion of... Vapors or the actual fuel itself... Not entirely sure. It's written on all petrol generators but I always fill my Mazda ute all the way up to the cap and it hadn't exploded yet Edit: Oops, bugger. There it goes Quote Link to comment Share on other sites More sharing options...
Simon Smith Posted August 21, 2012 Share Posted August 21, 2012 Being ex refrigeration engineer, my solution would be to use solenoid valves rather than electric pumps, these could be switched via a relay with another one to switch the fuel gauge. No bulky taps, just a changeover switch on the dash. Quote Link to comment Share on other sites More sharing options...
Gazzar Posted August 21, 2012 Share Posted August 21, 2012 So, not applicable to diesels, then? Quote Link to comment Share on other sites More sharing options...
Snagger Posted August 24, 2012 Share Posted August 24, 2012 Being ex refrigeration engineer, my solution would be to use solenoid valves rather than electric pumps, these could be switched via a relay with another one to switch the fuel gauge. No bulky taps, just a changeover switch on the dash. A bit like the dieselveg.com system, then. The problem with that, other than cost, is that any electrical fault can cause merry hell with your fuel system and could cause a power loss at a critical time. I prefer simplicity over complexity; Parrot's idea of just daisy chaining the return sides of the tanks seems pretty smart and reliable to me - just fit the retrun line from the engine bay through the top of the first tank and the outlet to the second tank from the first tank (a little below the top to prevent brimming, if you want, but the tanks have plenty of breathing space up the filler necks) and you're away. No valves, no electrics and all high enough to be well away from any sediment that could cause a blockage. Just clip the line over the transfer box at a level below the tops of the tanks to allow it to work and prevent it from fretting and all you need to do is make sure new gaskets are used to prevent leaks. The only flaw in the system is that you lose the redundancy of a selectable return line system, which means that a holed tank can't be deselected from the return system unless you re-rig the retun lines following the discovery of a leak, isolating the damaged tank, but what are the chances of this abeing a problem anyway? Quote Link to comment Share on other sites More sharing options...
ejparrott Posted August 24, 2012 Share Posted August 24, 2012 Just a wild though off the top of my head with no research into it, but where the T would be, fit a simple quarter turn ball valve each side before the pipework to the tank. Quote Link to comment Share on other sites More sharing options...
Xenocide Posted August 24, 2012 Share Posted August 24, 2012 Easiest way would just be to have two fuel tank selector taps and hook one up "backwards" so you have one input and two outputs and pop the return in that. The lightweight ones have switches on them for one position so you could wire it up so you have an idiot light on the dash if they're not both on the same tank which would (might) stop the problem of filling one and using the other. Quote Link to comment Share on other sites More sharing options...
Snagger Posted August 27, 2012 Share Posted August 27, 2012 Yep - I suggested that in the early posts. Quote Link to comment Share on other sites More sharing options...
reubsrover Posted August 29, 2012 Share Posted August 29, 2012 Well there's no point me starting a new post with my questions on this exact topic so I'll introduce myself here and ask away. I'm from the far off land of Australia and am venturing into new forums as I could well be the first to do a 200Di conversion over here. At least I haven't heard of anyone else who has done one. I too am in the middle of working out how to plumb the fuel system with duel tanks. My only suggestion that I can bring to the table is to link the breathers as an over flow as one or two of the chaps over her have done on various conversions. Can anyone point out and flaws in this solution? This is what I was leaning towards combined with a solenoid valve. Then I came up with the bright idea of simply returning the return line to the filter which already has a second 'in' line blocked off. Thought I should research a little first and was led by google to this excellent discussion. Now to overcome the problem of air in the lines. I'd like to set up in the not too distant future to run on SVO in one tank and thus this option for the return line is appealing. So with the knowledge that everything will be near new (reconditioned engine, new fuel lines/filter etc.) am I really that liekly to run into difficulties with air in the lines? Quote Link to comment Share on other sites More sharing options...
mikey7134 Posted August 29, 2012 Author Share Posted August 29, 2012 Welcome, Thanks for advice everyone - very helpful. Was having a think, and thought about veg oil - i take it SVO is veg oil? - in one tank, due to diesel being fairly expensive, and me being a student / very poor by the time me series is working again. This means either a manual or electric way to switch a feed and return line to the tanks, or tee in at the filter - options been discussed. Filter option having the benefits of no mixed fuels, and keeping oil warm. Air leak being the problem.. reubsrover - i would think that you wouldn't find an air problem with your set-up. And i'm thinkin for me, run like it for a bit, and if i get a problem, then time to introduce new seal / new lines or the de-aerator i linked to earlier. What i do know is that our Peugeot 205 went on many years running with air in the lines, but once started, ran fine, and although the air wasnt helping starting, about 1/2 of the 4 glowplugs worked.. So, i would think if its starting okay, especially after being sat for a little bit, then the engine should run fine.... reubsrover - have you got as far as housing your battery yet? Or got any plans for where to go? Cheers Quote Link to comment Share on other sites More sharing options...
reubsrover Posted August 29, 2012 Share Posted August 29, 2012 Thanks...hmm battery and exhaust are last on the list as I cannot weld to save myself. I was hoping although I haven't even done any measuring, to have a custom tray made up to fit under the middle seat and dropping down at the rear of the gearbox where your overdrive our PTO goes out in that general area anyway. Failing that I have seen a couple of trays for a dual battery setup welded to the rear of the chassis filling in space in the rear of the wheel arches . Not the best option with a gal chassis and nice tub. I don't have a gal chassis and my tub has a million holes with bolts through it due to a dodgy repair job. Quote Link to comment Share on other sites More sharing options...
Snagger Posted August 30, 2012 Share Posted August 30, 2012 Reub, have a look around my blog - I have a 200Tdi 109 with three fuel tanks, running on SVO and with twin batteries. Also documented on my blog is my wife's FFR Lightweight which has twin batteries located between the front seats as standard (I used the same type of FFR battery box to make a storage compartment under the cubby box on the 109). Look in the fuel, electrical, engine and Lightweight sections for details and photos of how it was all done. My experience of Tee-ing the return line into the fuel feed was fine first time around, but it caused trouble when I refit the SVO system - the slightest leak anywhere will allow air in; the low pressure side before and including the lift pump while running (as it's sucking on the fuel) and the high pressure side as the fuel gravity drains back to the tank with the engine off. These leaks can be a pig to find as the small leaks only let air in, not fuel out. You don't need to worry about recirculating hot oil through the filter to prevent clogging in the Australian climate, so return lines are the way to go. Don't worry about cross-tank contamination - it'll be small and of no effect. Quote Link to comment Share on other sites More sharing options...
reubsrover Posted August 31, 2012 Share Posted August 31, 2012 Reub, have a look around my blog... Hi Nick, don't worry I have been, it's an invaluable resource and I've spent many hours reading up on your work. Thanks very much for the effort you put into that blog, especially the wiring up of the TDi conversion. I will most likely put one return line in (my second tank doesn't have a second pickup port) and connect the breather pipes as an over flow system in case I accidentally use the tank without the return line first. Later on if I start using veg oil I will use the tank with the return line as diesel mixing in with the veg oil shouldn't be an issue. Seems to be the sensible way to do things, thanks for your advice. i take it SVO is veg oil? Yes mate, got that definition from Nick's great blog as well Quote Link to comment Share on other sites More sharing options...
Snagger Posted September 1, 2012 Share Posted September 1, 2012 SVO: straight veg oil, ie. unmodified new vegetable oil. Use sunflower or rapeseed oil, not palm or soya as the latter (cheaper) types have a lot of heavy fats which coke and gum the inside of the engine and turbo. WVO: waste veg oil, ie. second hand waste oil from cooking. Some use it as is, which is full of water, fats and sediment from the food cooked in it. It must be filtered carefully and "dried" to prevent injection system damage. Gravity filtering, which just means standing in a tank for a month, will work well - scoop out the fats and floating debris at the top and use the fuel from the middle. The bottom of the filtering tank will collect the water and heavy sediments. The problem is that most restaurants and take-aways use palm oil. The Aussies are really the most knowledgeable source of information on vegoil use - they have many forums about it and have been at it for decades. Reub, fitting an extra connection to a tank is easy (I had to do it to my front tanks) - all you need to do is drill the holes and use the cork gasket. In an ideal world, you'd fit captive nuts in the tank for the retaining screws, but rivnuts (or even normal nylock nuts if you use a military type underseat fill tank, as you can reach inside them if your arms are slender) will be fine as the gaskets surround the screws. Try to use a return port with the pipe that reaches near the bottom of the tank - a plain fitting (or using the vents) will work fine, but you will always hear the fuel pouring back into the tank. If you're going dual fuel, you really need to fit a return line selector valve right away as running on diesel while the engine warms up with a full SVO tank will cause the SVO tank to overflow (you would need to run the return tot hat tank as chemically, contaminating SVO with diesel is, if anything, a benefit, while contaminating diesel with SVO will contribute to coking of the engine and contamination of the sump oil while the engine warms up). Quote Link to comment Share on other sites More sharing options...
ejparrott Posted September 3, 2012 Share Posted September 3, 2012 My return pipe is actually only 3" long.....When I made it I figured it would help with mixing the diesel and bio, as I run a single tank system.....quite how much its helping I don't know...... Quote Link to comment Share on other sites More sharing options...
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