Cartman Posted January 18, 2010 Share Posted January 18, 2010 OK. Now a bit of background first. I am building/rebuilding a '66 ex-military 109 but it is now fitted with a 200tdi with a 300tdi turbo assy. So being ex-mil it has twin underseat fill tanks with a std mili manual fuel selection valve. Truck was originally 2.25 petrol. So I planned to keep both tanks and use one for pure diesel and the other for processed WVO. The problem is the IP fuel return. To get around the problem of diverting the IP return to the selected tank I wanted to direct this to the supply side of the fuel filter - but this results in too much air getting back into the system. Also as the fuel is planned to be FPHE heated prior to the fuel filter inlet from the tank the heat would then stay in that part of the system longer due to the recirc. If it worked...which it doesn't. So suggestions how to either stop the air from getting into the return from the IP or alternatives while still retaining manually selectable tanks? Cheers, Paul Quote Link to comment Share on other sites More sharing options...
simonr Posted January 18, 2010 Share Posted January 18, 2010 A swirl pot with a separate vent? You could probably use another one of the tank selector valves and gang it with the original to switch the return at the same time as the fuel? Si Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 18, 2010 Share Posted January 18, 2010 A 6-port changeover solenoid, or two 3-port ones? Quote Link to comment Share on other sites More sharing options...
Phil Hancock Posted January 18, 2010 Share Posted January 18, 2010 The original that LR did for a twin tank diesel was to slave a 2 way cock from the original tap. The tap is the same as used on Lister HR marine engines for the sump/gearbox emptying pump. On my 88" i used 2 std military taps but the return tap needed to be adjusted up well to avoid leaks. Quote Link to comment Share on other sites More sharing options...
twizzle Posted January 18, 2010 Share Posted January 18, 2010 A swirl pot with a separate vent? You could probably use another one of the tank selector valves and gang it with the original to switch the return at the same time as the fuel? Si hello Si what is a A swirl pot have you a photo or a link TWIZZLE Quote Link to comment Share on other sites More sharing options...
Cartman Posted January 18, 2010 Author Share Posted January 18, 2010 Just doing a Google I came up with this image which shows the theory. This came from this link and seems to sum up how the unit is intended to function (sans fuel filter). Theory seems sound and I would guess a 1 litre swirl pot would have the capacity but I would also need an LP fuel pump to top up this 'reservoir'. Swirl pot info So this system is doable but is adding complexity. If I could find out how to connect up another fuel selector on the back of the current one it would be the simpler option?The Dutch did it with their leaf LR's after all? Paul Quote Link to comment Share on other sites More sharing options...
Cartman Posted January 18, 2010 Author Share Posted January 18, 2010 A 6-port changeover solenoid, or two 3-port ones? aaah Pollack valves Jon. That's an option but I prefer the manual push a lever method Quote Link to comment Share on other sites More sharing options...
Cartman Posted January 19, 2010 Author Share Posted January 19, 2010 Thinking a bit more about this this morning around what would be the most cost effective option, and still allow me to use twin tanks in the way I plan to use them. So, keeping the manual tank supply selector the IP return will be going back to the main/drivers side tank. At tickover the flow will be the highest but under load it should be low. Now obviously the risk is if I had the reserve/pass tank selected and the main tank was full - it could then overflow. So at a high point on each tank I will fit a transfer/balance pipe between both. The main fuel supply line OD is 8mm so 10-12mm for the balance line. If there is a high concentration of WVO in the aux tank then it will just get slightly diluted by dieso? Sorta like this? Paul Quote Link to comment Share on other sites More sharing options...
Cartman Posted January 19, 2010 Author Share Posted January 19, 2010 The original that LR did for a twin tank diesel was to slave a 2 way cock from the original tap. The tap is the same as used on Lister HR marine engines for the sump/gearbox emptying pump.On my 88" i used 2 std military taps but the return tap needed to be adjusted up well to avoid leaks. Phil, Did you use two independant valves or rig them up back to back? If you did 'Siamese' them any chance of a pic? Cheers, Paul Quote Link to comment Share on other sites More sharing options...
Phil Hancock Posted January 19, 2010 Share Posted January 19, 2010 The taps on my 88" were one above the other on the heel board, IIRC the top one was in the standard position so the second was below. They were not linked so i could leave the return on the opposite tank to the suction if i wished. The piping was a bit tight to get in tho. Quote Link to comment Share on other sites More sharing options...
Ex Member Posted January 19, 2010 Share Posted January 19, 2010 If you have a balance line and don't mind the one tank overflowing into the other, then that works fine. I know others that do that. Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted January 20, 2010 Share Posted January 20, 2010 IIRC I have one of the manual change over valves in the garage, which was off a 1974 lightweight. If anyone wants it they are welcome for a forum donation. Mike Quote Link to comment Share on other sites More sharing options...
wuas680 Posted January 20, 2010 Share Posted January 20, 2010 I am wanting to do this to my 109 - once i work out how to fit a front tank to it. My plan was to use a standard military tap - the petrol type, and use the switch contacts on it not for switching the gauge read out but to switch on one of two single 12v fuel valves - much cheaper than a pollack. the valves will therefore select which tank the return line is open too, but retains the manual change over feel and look. Quote Link to comment Share on other sites More sharing options...
Cartman Posted January 20, 2010 Author Share Posted January 20, 2010 The taps on my 88" were one above the other on the heel board, IIRC the top one was in the standard position so the second was below. They were not linked so i could leave the return on the opposite tank to the suction if i wished. The piping was a bit tight to get in tho. Cheers Phil. The idea of 'ganging' them together sounded to much of a PITA and your system makes perfect sense IIRC I have one of the manual change over valves in the garage, which was off a 1974 lightweight. If anyone wants it they are welcome for a forum donation. Mike Thanks for the offer Mike but luckily I have ahd one already offered to me for the task but I am sure someone else will bite your hand off. They are not cheap after all? If you have a balance line and don't mind the one tank overflowing into the other, then that works fine. I know others that do that. Aaaah, some I am not the only nutter that has thought about it All I need now is one of the brass connections to fit to the top of the tank for the fuel return line. Anyone got one off an old tank? Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted January 20, 2010 Share Posted January 20, 2010 No probs It will sit in the garage till some one wants it, and if it is worth that much then a sizable donation to the forum funds will be required! :lol: Quote Link to comment Share on other sites More sharing options...
Cartman Posted January 25, 2010 Author Share Posted January 25, 2010 OK a slight change of plan. After a discussion with Minivin I have another alternative. IP return can be split to both tanks and then enters through a std Series fuel pickup pipe shortened to 1-2". As shown below. The fuel will look for the path of release resistance so filling the tank with the most space - so no overflow possibility. The issue is both fuel will become blended. Quote Link to comment Share on other sites More sharing options...
cieranc Posted January 26, 2010 Share Posted January 26, 2010 But still, a Pollack 6 port valve would overcome this, both fuels would be returned to their respective tanks with no dilution. Returning diesel to the oil tank is not necessarily a problem, but putting oil back into the diesel tank could eventually lead to cold start problems. Quote Link to comment Share on other sites More sharing options...
Bluemoon Posted January 26, 2010 Share Posted January 26, 2010 easiest way is just connect the return feed back to the fuel line before the lift pump, no mixing of fuel and only two solenoid valves needed, if wanted for svo then a very slighted different method but proved can be adopted. Brian Quote Link to comment Share on other sites More sharing options...
bobtail4x4 Posted January 26, 2010 Share Posted January 26, 2010 but that wont get any air out of the system. Quote Link to comment Share on other sites More sharing options...
Bluemoon Posted January 26, 2010 Share Posted January 26, 2010 the 300tdi can start with no diesel in the filters and any is lost in the combustion cylce, I've ran mine like this for four to five years now with no ill effects, maybe all you may have to do is a bleed on first start up , but after that I've never had any problems. Brian Quote Link to comment Share on other sites More sharing options...
Turbocharger Posted January 26, 2010 Share Posted January 26, 2010 I'd just be fitting a changeover valve to the feed and another to the return, and forcing myself to remember to switch both when I change it over. Surely ganging switches, solenoids etc is just adding the potential for overflow. A balance pipe will help to offset that, but it'd be much better to switch both lines. Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted January 27, 2010 Share Posted January 27, 2010 Bear in mind you will be wanting the lift pump to be before any filters - they aren't very good at sucking fuel, much better at pushing it. I've done exactly this many times on several landy fuel systems. I'll see if I can dig out a diagram. Quote Link to comment Share on other sites More sharing options...
Cartman Posted January 28, 2010 Author Share Posted January 28, 2010 easiest way is just connect the return feed back to the fuel line before the lift pump, no mixing of fuel and only two solenoid valves needed, if wanted for svo then a very slighted different method but proved can be adopted. Brian Tried that initially and it would not bleed. That is why I came to where I am now...wherever that is? Turbo, That is the direction I may be going. Two seperate mech valves as Phil also suggested. But still, a Pollack 6 port valve would overcome this, both fuels would be returned to their respective tanks with no dilution.Returning diesel to the oil tank is not necessarily a problem, but putting oil back into the diesel tank could eventually lead to cold start problems. That's why I wanted to use mechanical means and not a Pollack. Added complexity IMHO and there must be a simpler (and tidier) method. Which comes around to two mili fuel changeovers. All I need is one more and a set of dexterous fingers to pipe it. Mixing the fuel is something I want to avoid if poss Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted January 28, 2010 Share Posted January 28, 2010 It is possible to bleed it with a looped return. I've always run it with the return disconnected and running into a container, then reconnected the line. This will remove almost all air. The small amount that remains will eventually be injected, but won't affect the running of the engine. WVO conversions have used solenoid valves since their development. I have yet to hear of someone who has had a problem (discounting cheap eBay knockoffs!) Certainly I've run an ATG solenoid set on several landies totaling well over 50k miles with no issues. I went through several stages of development in the plumbing of my kit. I ended up with a diesel return to tank, a looped WVO return, and a bypass valve to allow WVO to circulate through the HX and filter while the engine was warming up. Quote Link to comment Share on other sites More sharing options...
Cartman Posted February 1, 2010 Author Share Posted February 1, 2010 It is possible to bleed it with a looped return. I've always run it with the return disconnected and running into a container, then reconnected the line. This will remove almost all air. The small amount that remains will eventually be injected, but won't affect the running of the engine. WVO conversions have used solenoid valves since their development. I have yet to hear of someone who has had a problem (discounting cheap eBay knockoffs!) Certainly I've run an ATG solenoid set on several landies totaling well over 50k miles with no issues. I went through several stages of development in the plumbing of my kit. I ended up with a diesel return to tank, a looped WVO return, and a bypass valve to allow WVO to circulate through the HX and filter while the engine was warming up. Cheers for that James so I will give that a go. I have to be honest the system was plumbed in and run up then I resorted to an open return when we located the problem. We didn't give it another go. The reason for the avoidance of the pollack style valves is simplicity really (and asthetics with less stuff on the b/h). I want to stay mechanical wherever poss. Less wires and complexity K.I.S.S Quote Link to comment Share on other sites More sharing options...
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