mart010 Posted May 30, 2023 Share Posted May 30, 2023 Hi everybody! Got a new issue with my series 3 military 109 lwb. The diesel tanks are pretty dirty. I removed both diesel tanks from the car. Checked the pipes and repaired the switch piece to switch between both tanks. The tanks are pretty dirty inside. I still want to see if I can clean them. Both tanks still contained about 20 liters of old diesel or something similar. I don't know exactly what was in it. What I took out was liquid, but also with a thick black slurry. That black slurry is almost hardened on the rim and a thick viscous layer on the floor of the tank up to the height where the liquid has been. Is not fully cured and smells very strongly of linseed oil or something. Not so much diesel. I have tried to dissolve the liquid with fresh diesel and small pebbles. It does not work. I have tried parts to soak with gasoline left for 3 weeks. That seems to help a bit. But the vast majority is partly so hard that it will not work in this way. This is what the inside looks like. The 'yellow' liquid is the new pebbled diesel. It is therefore about the black edge, which is also below the diesel on the bottom. You can see rust at the top of the tank. See the picture of the inside of the cap. I expect to clean it with steel wool. Does anybody know how I can clean the inside of the fuel tanks. Thanks in advance!! Quote Link to comment Share on other sites More sharing options...
steve b Posted May 31, 2023 Share Posted May 31, 2023 An industrial steam cleaner/vapour blaster would probably get rid of most of it. I can say one thing - the only new ones available are pattern and the quality is sub standard to say the least - the last pair I had 12 months ago would not accept the filler filter/tube and the original caps would not tighten or seal. I ended up cutting the entire top out of both old ones and welding to the new tanks All the deposits in yours and rust is a result of SVO sitting in it long term Steve Quote Link to comment Share on other sites More sharing options...
mart010 Posted May 31, 2023 Author Share Posted May 31, 2023 8 hours ago, steve b said: All the deposits in yours and rust is a result of SVO sitting in it long term Hi Steve, thanks for your respond. What is the best treat to get rid of SVO? I also got advise to use caustic soda. Would that be possible? Or will I harm the inside of the tanks using caustic soda. Quote Link to comment Share on other sites More sharing options...
steve b Posted May 31, 2023 Share Posted May 31, 2023 I have heard of concrete cleaner used to clean tanks but boiling water and washing machine powder might be better if you're doing it manually ? The industrial steam cleaner would be my choice I think, with degreaser dosing Steve 1 Quote Link to comment Share on other sites More sharing options...
ped Posted May 31, 2023 Share Posted May 31, 2023 caustic is fine with steel but don't let it near anything aluminium plus it's nasty stuff so rubber gloves and eye protection i use it as part of the process to anodise and usually use 100g/litre and heat to about 40c 1 Quote Link to comment Share on other sites More sharing options...
Gazzar Posted May 31, 2023 Share Posted May 31, 2023 Remove, add caustic. Put in cement mixer with a steel chain inside. Turn on mixer. Quote Link to comment Share on other sites More sharing options...
Gazzar Posted May 31, 2023 Share Posted May 31, 2023 Repeat. Quote Link to comment Share on other sites More sharing options...
mart010 Posted June 1, 2023 Author Share Posted June 1, 2023 14 hours ago, ped said: use it as part of the process to anodise and usually use 100g/litre and heat to about 40c Hi Gazzar, to anodise. Is that simultaneously with cleaning or after? And how exactly? Quote Link to comment Share on other sites More sharing options...
ped Posted June 1, 2023 Share Posted June 1, 2023 caustic is part of the claning process and strips the top layer of ally oxide off (to remove anodising i use a 200g/litre solution my procees for anodising is 1 clean part with hot water and washing up liquid 2 rinse with clean water 3 into a non caustic hot chemical de greaser 4 rinse 5 into caustic to etch 6 rinse 7 into nitric acid to de smutt other impurities 8 rinse 9 into sulphuric acid to do the anodising 10 rinse 11 into dye till colour is to the level you want 12 rinse 13 into csl to seal the anodising for 30 mins /you can boil for 30 mins in hot water but i prefer the csl 14 rinse 15 polish with autosol 1 Quote Link to comment Share on other sites More sharing options...
mart010 Posted June 1, 2023 Author Share Posted June 1, 2023 Hello Ped, thanks for your answer. Lot of steps to undertake. Not sure if I want to do that. The caustic worked very nice. Some rust at the top of the tank I need to redo. Rest is almost clean. 2 Quote Link to comment Share on other sites More sharing options...
steve b Posted June 1, 2023 Share Posted June 1, 2023 That has come out very well, your process is noted for the future Steve Quote Link to comment Share on other sites More sharing options...
Mossberg Posted June 2, 2023 Share Posted June 2, 2023 Wow, I bet you are pleased with that. Have a look into phosphoric acid solution to kill the rust. It won't protect the steel but hopefully neutralise the rust if you are thinking of using an internal tank paint. If you look for "PH Down" on ebay as I think that is 80% phosphoric acid. However, when you mix acid with water, it's extremely important to add the acid to the water rather than the other way around. This is because acid and water react in a vigorous exothermic reaction, releasing heat, sometimes boiling the liquid. if you do use a phosphoric acid solution I think it is recommended to have between a 20 and 40% mix of acid. Also remember that it is acid so use relevant protective equipment! 1 2 Quote Link to comment Share on other sites More sharing options...
ped Posted June 2, 2023 Share Posted June 2, 2023 when using acids/alkalines it is always good to have fresh water to hand incase you get splashed on unprotected skin or surfaces 1 Quote Link to comment Share on other sites More sharing options...
ped Posted June 2, 2023 Share Posted June 2, 2023 11 hours ago, mart010 said: Hello Ped, thanks for your answer. Lot of steps to undertake. Not sure if I want to do that. The caustic worked very nice. Some rust at the top of the tank I need to redo. Rest is almost clean. you can miss some of the steps out look online for a basc guide and Gateros plating are a good firm to do you a kit 1 Quote Link to comment Share on other sites More sharing options...
mart010 Posted June 7, 2023 Author Share Posted June 7, 2023 (edited) Hi, I've orderend Rustbuster to get the last rust out. After that I'm leaving the inside as is. The outside has been coated with RX5 and RX10. Looks neat. Almost ready to reinstall, rewire and try out with diesel. Thanks for the help so far. Edited June 7, 2023 by mart010 Quote Link to comment Share on other sites More sharing options...
mart010 Posted June 22, 2023 Author Share Posted June 22, 2023 On 6/2/2023 at 10:59 AM, ped said: you can miss some of the steps out look online for a basc guide and Gateros plating are a good firm to do you a kit Well, turns out that cutting corners is not the way forward. I’ve got the tanks clean but started rusting again pritty quick. I put some diesel in to stop the rust process. No good solution for the long run I guess. Ok, your anodising steps are noted Ped. Need to do that to get a better result. Above picture is after using caustic soda and rust converter. Looks nice and clean. this is 12 hours later. After this I put some diesel in hoping to stop the rust process. State the tank is in right now. I bought an extra diesel filter to install after the tanks. Just to be sure. Or maybe I will buy new tanks to get going and try ALL the steps again, including anodizing. Quote Link to comment Share on other sites More sharing options...
Snagger Posted June 22, 2023 Share Posted June 22, 2023 Has anyone tried the POR15 treatment? I think it’s an epoxy like substance that lines the tank after thorough cleaning. I was going to try that. Quote Link to comment Share on other sites More sharing options...
AlWorms Posted June 22, 2023 Share Posted June 22, 2023 I've used the POR15 tank treatment YEARS ago, on an aircooled VW tank. I followed the instructions, and it seemed to work well enough, though it wasn't a car I ever used on the road. It had fuel in it for years and was run 3 or 4 times a year, and had no problems. It was very early 2000's. I can't give any more feedback than that, but it certainly didn't dissolve when petrol was in contact with it, anyway. I used the excess I poured out to paint the outside of the tank, and that seemed to stay on well, too. 1 Quote Link to comment Share on other sites More sharing options...
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