jerboa Posted November 8, 2011 Share Posted November 8, 2011 Super quick question. I'm shortly going to be embarking on a 200tdi conversion into my '81 Series Three 109" station petrol wagon. I've done all the research and I'm planning it out exactly to the last nut+bolt before I start. I have one question remaining - all of the forums/research resources I have looked up/on in order to solve this question has as-yet failed to provide an answer. The vehicle is currently petrol (also LPG), so the fuel system has one delivery pipe. TDi's have/need a return pipe. My question is this. Can I fit a diesel sender to the tank in order to facilitate the installation of a return pipe? Or do I have to make a hole in the tank to fit the return? The other option is to put a T-piece in the fuel vent pipey-thing - but will that leak diesel out the top? I quite fancy the latter solution.. My intention is to remove the tank and repaint/refit etc prior to undertaking the work. Thanks guys, Quote Link to comment Share on other sites More sharing options...
Andy Posted November 8, 2011 Share Posted November 8, 2011 The vent shouldn't leak if it goes high enough above the return pipe, as normally the vent will be allowing air into the tank to replace fuel that's being used. Quote Link to comment Share on other sites More sharing options...
western Posted November 8, 2011 Share Posted November 8, 2011 there's no spill return connection on a 200tdi fuel sender unit only the fuel pick up to the lift pump/filter. on a 110 the return pipe is connected to a seperate pipe on top of the fuel tank. Quote Link to comment Share on other sites More sharing options...
Andy Posted November 8, 2011 Share Posted November 8, 2011 From memory the return on a Disco is separate to the sender as well. Quote Link to comment Share on other sites More sharing options...
Jon White Posted November 8, 2011 Share Posted November 8, 2011 You need the return fitting from a diesel series then this fits bolts in place of the blanking plate that is on the top of the tank. Shimples..... Jon Quote Link to comment Share on other sites More sharing options...
discomikey Posted November 8, 2011 Share Posted November 8, 2011 you can just return the fuel pipe back into thefilter housing. however my fuel tank had a blanked off hole which i used to make a return pipe using copper brake line and connectors and the blanking plate to make a diesel/air tight return back to the tank. either way will work. Quote Link to comment Share on other sites More sharing options...
Gazzar Posted November 8, 2011 Share Posted November 8, 2011 I'd not recommend the filter route - the diesel coming back from the pump can have some air in it - and routing this diesel back to the tank is the way the system purges the air. When I did my 1981 109 I ran a return pipe to the tank and plumbed it into the air pipe that balances the two upper chambers of the fuel tank. I have had no problems with this approach so far (1,500 miles). I used a "tee" piece robbed from a Gunson vacuum gauge set. It was really easy - and I didn't have to drop the tank to do it as I was able to do it through the inspecion panels in the floor of the loadbed! Hope this helps. Quote Link to comment Share on other sites More sharing options...
jerboa Posted November 8, 2011 Author Share Posted November 8, 2011 I have seen people run it back to the filter - and they had problems.. One of the things I was wondering about was if the diesel sender incorporated a fuel return, but if as Jon says - there's a separate return, then I just need one of them. Cant imagine it'll be easy to find one though!! Maybe I'll do as Gazzar says.. Quote Link to comment Share on other sites More sharing options...
integerspin Posted November 9, 2011 Share Posted November 9, 2011 I ran with the return teed before the lift pump. People said there will be air in the returned diesel, where does air come from? I ran it for two years and not a problem, keeps the chip oil nice n warm, infact you might find some filters don't liek the heat. My reason for doing it , apart from it was quick, was with military tanks you need taps to direct the return. Only problem I found was if you don't clamp off the return bleeding takes forever. I put the returns in to the tank after a few years, mainly to see if it would be any different. I didn't have any alternatives to drilling into the tank, so I drilled a hole and bolted an old fuel banjo into the top of the tank with a banjo bolt. The banjo worked perfectly on one side but the other side leaked, so I made a couple of brass filttings to bolt to the tanks. I put the return into the vent on someones 2A it worked perfectly. Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted November 9, 2011 Share Posted November 9, 2011 Super quick question. I'm shortly going to be embarking on a 200tdi conversion into my '81 Series Three 109" station petrol wagon. I've done all the research and I'm planning it out exactly to the last nut+bolt before I start. I have one question remaining - all of the forums/research resources I have looked up/on in order to solve this question has as-yet failed to provide an answer. ... I think this will answer wrt part numbers, note that the return elbow is a different number to the pick-up elbow. PA Blanchards quote a (reasonable) price for 500818, but that doesn't mean they stock it. Oh, and while searching for the part number I found this thread :-) HTH Quote Link to comment Share on other sites More sharing options...
jerboa Posted November 14, 2011 Author Share Posted November 14, 2011 Sounds like some good info.. Thanks Guys! Quote Link to comment Share on other sites More sharing options...
ejparrott Posted November 14, 2011 Share Posted November 14, 2011 I think the return pipe is shorter than the suction. I made my own stainless return fitting as I couldn't source one. I made it only 2" long, and this means that when the fuel level starts dropping, it ensures the bio and diesel get mixed....or at least it does in the winter when I actually use Diesel, in the summer I run 100% Bio. Quote Link to comment Share on other sites More sharing options...
stumonkey17 Posted November 21, 2011 Share Posted November 21, 2011 Sorry for the slight sideline for this question but I've always wondered why diesels need a return pipe. I assume it's something to do with a petrol carb only pulling the required amount of fuel so there is nothing to return. If this is so then why does a diesel injector pump pull excess fuel? I'm sure there's a simple answer that more knowledgable souls know but prior to my current experiences with land rovers I'd only ever worked on petrol engines so it's still a mystery to me. Quote Link to comment Share on other sites More sharing options...
Snagger Posted November 21, 2011 Share Posted November 21, 2011 The injection pump and injectors need to be lubricated and cooled by the fuel, so need high flow rates from the lift pump. A Tdi on over-run (such as on a long hill descent) returns a huge amount of fuel to the tank - I'd guess as much as few pints every minute. I have tried the loop system, adding a T-piece just before the lift pump, so that the spill fuel would feed straight back into the lift pump, reducing strain on the pump and minimising the chance of sucking air in through a pinhole leak anywhere between the tank and lift pump (both because the pump will not have to such so hard on fuel all the way from the tank), but mainly to simplify the return system and keep the fuel hot when running on vegoil. It works well enough, but it does make bleeding the injection system difficult after replacing the filter or working on any part of the system, needing multiple bleeds until clear and fastidious scrutiny over the system being utterly air tight. Quote Link to comment Share on other sites More sharing options...
stumonkey17 Posted November 21, 2011 Share Posted November 21, 2011 Thanks Snagger. I thought there would be a simple reason but hadn't considered lubrication and cooling. One of the best thing about this forum is people's willingness to share their knowledge. Quote Link to comment Share on other sites More sharing options...
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