The grand experiment- cleaning a gas tank while still in the bus

[mainstreetprod]

The first thing you should know is if you tell me I can't do something- I'll at least try to prove you wrong. I've found no attempts on the Samba to clean a tank without taking it out of the bus, so I thought I would give it a try. Really nothing to lose and everything to gain. Problem: tank in my FI '78 has lots of rust flakes and trash stopping up the filter within a few miles. After some exhaustive research on other sites, (mainly motorcycle) came up with a plan. Here's what I did over the last two days:

1) Disconnected outlet and recirculation hoses from tank, drained the gas , put the short hoses back on and clamped them off, using a small fuel line clamp from Harbor Freight.

2)Cut an access hole to remove the sender. I used a 4 1/4" hole saw. Removed sender unit and inspected. Mine had broken rheostat wires, not repairable, so ordered a replacement with O ring.


3) Put 8 gallons of Apple Cider vinegar in the tank to dissolve the rust. It's 5% acid. Put some vinegar in a garden sprayer and sprayed upper areas of tank with it two or three times.

4) Wait 24 hours. Removed the clamps and drained the vinegar. Used a wire to clear the inlet/outlet pipes, making sure water poured out freely. They kept clogging but eventually ran free.


5) Inserted garden hose in fuel filler inlet and turned on. Inserted shop vac hose in sender hole (a 24" hard plastic extension attachment works best). Vacuumed water out as fast as it came in. Did this 20 or 30 times with a 5 gallon shop vac. First 10 times came out rusty color with chips and flakes. Gradually started getting clearer and less flakes. Finally got only clear water. Several times, put hose spray nozzle in the sender hole and "pressure washed" the tank all around. Usually got a load of rusty flakes afterward. Used a 36" long brush with flexible wire handle from a wine making store to put down the hole and scrub inside of tank top, bottom, sides, loosening rust.

6) Vacuumed out all water and using a garden sprayer, sprayed inside of tank with water/baking soda solution. This neutralizes the acidity of the vinegar working on the metal.

7) Filled tank with water again and vacuumed out. Got a load of rust colored water again due to the chemical reaction. After that, clear again, no dirt or flakes. Drained all water. Metal in bottom of tank looked clean and non rusty as long as it was wet. Vinegar did a great job of dissolving the rust.

Dried tank out by putting hair dryer in sender hole. Tank dried quickly but bare metal started "flash rusting" immediately. Was ready for this, had a can of spray rust preventative from parts store. Put straw down sender hole and sprayed tank interior with preventative.


Tomorrow I'm going to replace the fuel filter, connect everything back up and fill 'er up. I'll update this thread on how it worked.

[TDCTDI]

Since you had the sender out, you shoulda used one of those telescoping magnets to fish out as much flakyness as you could. You could also drop a magnet in the tank & let it capture any remaining rust floating around.

A few bottles of isopropyl alcohol will flush the remaining water & evaporate quick enough to avoid flash rust.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[mainstreetprod]

Tried a magnet in a sock through the gas filler hole on the end of a drain snake. No luck, picked up virtually nothing. The rushing water from the garden hose into the shop vac got most everything, flash rust is the only issue now. I'll give the alcohol a try tomorrow if there is much of it.

[raygreenwood]

If rust was your problem.....24 hours of vinegar is not an answer.

Acetic acid in vinegar is a very weak acid. 5% is nothing to rust without DAYS of soaking.....and if you have thick rust you need agitation or stirring periodically to change out the acid that neutralizes itself in contact with the rust. With vinegar a simple water rinse will be more than enough to neutralize the weak acid left over.

If you have thick crusty rust in the tank....a better product would be a gallon or two or something like Jasco metal prep and prime. Pour in about 1.5 gallons straight ...at most dilute it 20% with water to get a larger volume. The object to start.....is to get this product into the tank in high concentration.....because it will DISSOLVE RUST.

Use a big swab made of something like a stick with cloth stapled to the end.....through the opening to repeatedly get fresh solution on areas like the tank seam.....use your sprayer to get it on the roof of the tank. It will fizz as it dissolves rust down to bare metal.

Spend an hour or so moving this product around. Inspect through the hole of you can with a flashlight for rust disappearing.
Drain this out. DO NOT NEUTRALIZE yet.
Take your last half gallon and dilute it 2.5x with water. Take that product and pour it into the tank and use your swab and sprayer to make sure all surfaces have been wetted at least twice.
Drain this out and let the tank dry for 24 hours. This will CONVERT any remaining surface rust to iron phospate. There is no need to neutralize this product. This is not an oxidizing acid like hydrochloric acid.

Rinse the tank with water...dry it well and fill it up with fuel. Short of pulling the tank to make sure you get all surfaces treated.....this is the best you can do.

Take all of the old acid in a tub.....add about 3x water to its volume and slowly pour in a 5 lbs box of baking soda to neutralize the product and then pour it,down the drain. Ray

[mainstreetprod]

I wouldn't characterize my rust problem as "thick, crusty"- just typical surface rust resulting in some flakes big enough to clog things up. I was impressed with what the vinegar did in 24 hours, a huge improvement. The lanolin based rust preventative I used, Fluid Film, coated the tank with a non drying film. I installed a new filter, connected everything back up and took it for a long drive. Seemed like a different bus, finally had all the power it should have and takes hills with ease. The engine is running distinctly cooler due to no longer running lean. If any of this changes, I'll come back and update. Still need to install the new sender when it arrives next week. For now, just put the old one back in.

[raygreenwood]

[vwjetboat]

we use to dry gas tanks by hooking long radiator hose to exhaust of car and stick in tank.. but then we use to weld on live tanks to.. uggggg the days of radiator / gas tank repair..
Good job on the tank.. if the filter stays clear .. hope it does..

[mainstreetprod]

After a few weeks, I would say the experiment was a success.Did get a bit of fine silt in the clear filter but not enough to clog it. Bus is still running fine (except for overheating after a certain amount of time, a separate issue.)

[Tcash]

Did this 20 or 30 times
The Vinegar treatment or just the Water?

Thank you for the write up. Got any pix?
Tcash

[mainstreetprod]