reb78 Posted January 30, 2021 Share Posted January 30, 2021 Is that a heated fuel filter head you are running? I have one as part of a long planned veg oil but have not fitted it as I wanted to do it as part of a twin tank system. I havent done that yet as my tdi runs fine in the summer on veg without any mods and i didnt want to overheat diesel when i am running on that by having a heated filter head fitted. Quote Link to comment Share on other sites More sharing options...
youngengineer Posted January 30, 2021 Share Posted January 30, 2021 4 hours ago, reb78 said: Is that a heated fuel filter head you are running? I have one as part of a long planned veg oil but have not fitted it as I wanted to do it as part of a twin tank system. I havent done that yet as my tdi runs fine in the summer on veg without any mods and i didnt want to overheat diesel when i am running on that by having a heated filter head fitted. Yes, I run full time on Veg. To avoid the issue you talk of, I thought of adding a bypass valve just before the heat exchange but since I pretty much always run on veg ive never worried about it. Quote Link to comment Share on other sites More sharing options...
reb78 Posted January 30, 2021 Author Share Posted January 30, 2021 30 minutes ago, youngengineer said: Yes, I run full time on Veg. To avoid the issue you talk of, I thought of adding a bypass valve just before the heat exchange but since I pretty much always run on veg ive never worried about it. I had similar thoughts with mine. But I just switch to diesel when the temps drop currently. My plan was always two tanks - diesel and veg oil, two electric lift pumps controlled by the same button as used for the Pollack 6 port valve. The veg would then run through a heat exchanger and then the heated filter head. A valve to turn off in the warmer months would probably still be handy as the heat exchanger might have been sufficient to warm the veg oil. Currently though, I just put SVO in the tank between April (ish) and late October (ish) (adapt if the temps are cold) and it works fine with no modifications. I should twin tank it really to allow me to purge the system and use veg oil for more of the year. Quote Link to comment Share on other sites More sharing options...
Snagger Posted January 31, 2021 Share Posted January 31, 2021 I have a multi plate type heat exchanger in the heater matrix circuit doing the same thing, with twin front tanks and a standard rear tank, so I can use different fuels. I also installed the electric sandwich plate to heat the fuel filter. Worked well with rape seed oil, but never got the same performance with sunflower oil. Quote Link to comment Share on other sites More sharing options...
reb78 Posted January 31, 2021 Author Share Posted January 31, 2021 When you say front tanks Snagger do you mean under the driver and passenger seats? Or somewhere else? My plan was to build one to go in the rear quarter panel on the passenger side of the 110. There is space there for roughly 40L I think. Diesel in there, SVO in the main tank then. Quote Link to comment Share on other sites More sharing options...
Sigi_H Posted February 1, 2021 Share Posted February 1, 2021 19 hours ago, Snagger said: Worked well with rape seed oil, but never got the same performance with sunflower oil. Don't use sunflower oil. It builds up coal on the injectors. Quote Link to comment Share on other sites More sharing options...
monkie Posted February 1, 2021 Share Posted February 1, 2021 On 30/01/2021 at 4:46 PM, reb78 said: I should twin tank it really to allow me to purge the system One thing I've always wondered on this sort of set up to purge the fuel system of SVO with DERV is the return lines. Won't this gradually return SVO into the main diesel tank so you end up with a mix or this just so negligible that it can be ignored? Of course this tank will eventually run low so you have to fill up from the petrol station, but I would have thought that this would be a rare event given the relatively small amount of time you run on DERV. Quote Link to comment Share on other sites More sharing options...
Sigi_H Posted February 1, 2021 Share Posted February 1, 2021 I used to run on rape seed oil for years, but I am not familiar with your short forms. What is DERF? What is SVO? I finished it, when I moved to Switzerland. I didn't find a farmer to refuel large quantities I ran the two tank solution like here Quote Link to comment Share on other sites More sharing options...
monkie Posted February 1, 2021 Share Posted February 1, 2021 DERV is the UK term for pump diesel (diesel engine road vehicle). SVO I believe is straight vegetable oil, ie other than filter it no other treatment to the oil has been done such as conversion to biodiesel. Quote Link to comment Share on other sites More sharing options...
Snagger Posted February 1, 2021 Share Posted February 1, 2021 Most veg oils do. Palm oil is particularly bad. I hadn’t used SVO in a long time before the car was laid up. Quote Link to comment Share on other sites More sharing options...
reb78 Posted February 1, 2021 Author Share Posted February 1, 2021 2 hours ago, Sigi_H said: Don't use sunflower oil. It builds up coal on the injectors. Ive been using it and rapeseed (Whatever is available when the supermarket offers are on) for about 100,000 miles and 8+ years with no ill effects. I prefer rapeseed as the engine 'feels' more responsive but sunflower oil works fine. Quote Link to comment Share on other sites More sharing options...
reb78 Posted February 1, 2021 Author Share Posted February 1, 2021 (edited) 42 minutes ago, monkie said: One thing I've always wondered on this sort of set up to purge the fuel system of SVO with DERV is the return lines. Won't this gradually return SVO into the main diesel tank so you end up with a mix or this just so negligible that it can be ignored? Of course this tank will eventually run low so you have to fill up from the petrol station, but I would have thought that this would be a rare event given the relatively small amount of time you run on DERV. Yes. I have pondered this, but it will be small amounts as you say and with the mileages I do, I think I would probably just run the diesel through every now and then to flush everything out anyway. I am not sure there is any other way. Edited February 1, 2021 by reb78 Quote Link to comment Share on other sites More sharing options...
Snagger Posted February 1, 2021 Share Posted February 1, 2021 2 minutes ago, reb78 said: Yes. I have pondered this, but it will be small amounts as you say and with the mileages I do, I think I would probably just run the diesel through every now and then to flush everything out anyway. I am not sure there is any other way. A lot of people loop the return line to the lift pump to avoid fuel tank contamination. The problem is purging air from the system. I tried it and the air in the pumps gradually built up to cause trouble. You could fit some sort of bleed system to the loop, perhaps. Quote Link to comment Share on other sites More sharing options...
reb78 Posted February 1, 2021 Author Share Posted February 1, 2021 1 minute ago, Snagger said: A lot of people loop the return line to the lift pump to avoid fuel tank contamination. The problem is purging air from the system. I tried it and the air in the pumps gradually built up to cause trouble. You could fit some sort of bleed system to the loop, perhaps. I need to draw it out and plan it properly. Thing is, it runs so well (in mine and I know you didn't have the same experience) with no modifications that adapting the system has taken a back seat. I have most major bits for the conversion other than the extra tank. Quote Link to comment Share on other sites More sharing options...
reb78 Posted February 1, 2021 Author Share Posted February 1, 2021 30 minutes ago, Sigi_H said: I used to run on rape seed oil for years, but I am not familiar with your short forms. What is DERF? What is SVO? I finished it, when I moved to Switzerland. I didn't find a farmer to refuel large quantities I ran the two tank solution like here That's interesting. Thanks. I need to read it properly and may have missed it but where did your extra tank go? Quote Link to comment Share on other sites More sharing options...
Snagger Posted February 1, 2021 Share Posted February 1, 2021 It’s worth doing. Mine ran beautifully on rapeseed (the 200 with the fuel heater, not the standard 300, which seemed ok until it started hunting at 2000 rpm). The carbon deposits on the 200 could be from a number of issues, possibly SVO, but more likely an issue with the rings or bores, as it always burned oil since the reborn and breathed more than I’d expect. It could be that I added Slick 50 too early and prevented proper running in, or it could be a bore dimension problem, but I suspect that more than the SVO use. Quote Link to comment Share on other sites More sharing options...
Snagger Posted February 1, 2021 Share Posted February 1, 2021 Sigi, SVO is straight veg oil, ie. unmodified clean vegetable oil. It’s s a term used in the UK but extensively in Australia, where the practice seems to have been pioneered and then pursued heavily. There is a lot of expertise down there. There is also the term WVO, waste veg oil, for oil that has been used before (generally cooking) and is then filtered but not modified for fuel use. Quote Link to comment Share on other sites More sharing options...
jeremy996 Posted February 1, 2021 Share Posted February 1, 2021 I have run a two tank system since 2009 running mainly on recycled soya oil, (although the truck was very fond of out of date cold pressed rape seed oil). The only active return line was into the SVO tank, as diesel into oil was easily mixed but cold oil into diesel isn't. I have a TUV approved kit, supplied from Germany and used to be retailed by DieselVeg in Wolverhampton, (now gone). Nearly 200k and counting. 1 Quote Link to comment Share on other sites More sharing options...
reb78 Posted February 1, 2021 Author Share Posted February 1, 2021 One return line was one thought I had but do you empty your diesel tank very quickly that way or is the amount negligible? I suppose better to empty the diesel tank and refill that rather than mix fuels. Where is your second tank Jeremy? Mods - I think i have taken this thread off in a different direction... Is it worth splitting it somehow as I have re-railed the discussion on the Head Gasket issues! Quote Link to comment Share on other sites More sharing options...
Sigi_H Posted February 1, 2021 Share Posted February 1, 2021 4 hours ago, reb78 said: That's interesting. Thanks. I need to read it properly and may have missed it but where did your extra tank go? As an extra tank I had a boat tank in the foot compartment of the second seat row. Need it? 😁 https://heiderei.ocloud.de/index.php/s/gMBf34wXtjFydgt Quote Link to comment Share on other sites More sharing options...
reb78 Posted February 1, 2021 Author Share Posted February 1, 2021 28 minutes ago, Sigi_H said: As an extra tank I had a boat tank in the foot compartment of the second seat row. Need it? 😁 https://heiderei.ocloud.de/index.php/s/gMBf34wXtjFydgt I looked at that as an idea but I often have passengers so it would take up foot space there unfortunately. The same manufacturers also do a tank that is very hit and miss for a fit in the rear wheel arch of the 110 (opposite side to the existing filler in the big space behind the rear wheel and above the exhaust) and but I think it would be about 4mm too large to fit there from previous measurements. I am leaning towards making my own to fit in there. Quote Link to comment Share on other sites More sharing options...
Sigi_H Posted February 1, 2021 Share Posted February 1, 2021 (edited) Since my car is for traveling with 2 persons only, that was ok for me. Now I removed the tank a have a packraft there. Edited February 1, 2021 by Sigi_H Quote Link to comment Share on other sites More sharing options...
jeremy996 Posted February 1, 2021 Share Posted February 1, 2021 2 hours ago, reb78 said: One return line was one thought I had but do you empty your diesel tank very quickly that way or is the amount negligible? I suppose better to empty the diesel tank and refill that rather than mix fuels. Where is your second tank Jeremy? Mods - I think i have taken this thread off in a different direction... Is it worth splitting it somehow as I have re-railed the discussion on the Head Gasket issues! My 110 has a LR90 military tank mounted backwards under the drivers seat. (Bearmach pattern part). As my truck is usually on SVO, the amount of diesel pumped across is small but noticeable. Lots of purging and switching from diesel to SVO and back again taint the SVO with diesel quite quickly, but it does mean the SVO will still flow when cold. Quote Link to comment Share on other sites More sharing options...
Snagger Posted February 2, 2021 Share Posted February 2, 2021 17 hours ago, reb78 said: One return line was one thought I had but do you empty your diesel tank very quickly that way or is the amount negligible? I suppose better to empty the diesel tank and refill that rather than mix fuels. You can do as Jeremy has and run the return line to the SVO tank. That way, excess fuel of either type can only go there, so you don’t contaminate the diesel tank and any diesel in the SVO is harmless (actually beneficial in cold conditions). The only problem with that system is that when running on diesel with a full SVO tank, you could overflow the SVO tank. You’d be surprised at how much fuel the return line system sends back on a Tdi, especially if the engine is on overrun long descents. Quote Link to comment Share on other sites More sharing options...
Sigi_H Posted February 2, 2021 Share Posted February 2, 2021 1 hour ago, Snagger said: You’d be surprised at how much fuel the return line system sends back on a Tdi It is ca. 1l per minute. Quess where I know that from 😉 Quote Link to comment Share on other sites More sharing options...
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