Cleaning/Sealing a fuel tank

[930dreamer]

Originally Posted by DieselPaul

I am working on cleaning my tank for my '72 SL now, I just blow through the lines between each step.

I add a 4th step, I start by doing a few shakes and cleans with hose water and dish soap to knock off the easy to get crud, that way the $70 chemicals work on the hard stuff.

I am working on Step 1 (2) which is the KBS Aqua Kleen, my tank had a decent amount of flakes floating around in it.

If you can't find someone to do it, greyhound my girlfriend and I your tank, I'd be happy to do it for you.

I've been working on the tank in between everything else going on. I removed the strainer bolt/plug, that was a bear. I still can't get a piece of wire to go all the way through the return line. I've used a drill with the wire but it's a no-go at this time. The wire has muck on the end so I know it's a mess in there.

[barry123400]

The gas tanks are made of steel coated on both sides with lead during the manufacturing of the sheet metal. American made fuel tanks used a sheet metal product called tern steel.

The lead coating was a lot thicker in the old days then in the last thirty or so years. If old gas has dried out the grunge that remains can be disolved with laquer thinner. Rust and dried out fuel residue look somewhat simular.

If the lead coating has been breeched rust may then be involved. It is wise to try a little laquer thinner to see if it dissolves and cleans the tank before getting aggressive.

If there is really rust in there I used to use muturic acid but protect yourself as it is a pretty strong chemical. It used to strip down to the bare metal pretty well. This acid is sold under several names but masonary guys use it to clean mortar off. It usually sells for about ten dollars a gallon or less in most hardware building supply type of places. A gallon usually did an average tank if it was really corroded in there.

Coatings are subjective and some have been updated to cope with some of the additives like alcohol. I have not kept track. Make really sure the tank has dried out well before coating.

The exhaust hose from a vaccum cleaner can be utilized on a nice day to speed up the dry before coating. Whatever coating used it is important to follow the directions. It takes time to rotate or slosh the tank over and over again to get equal coverage or something approaching it.

[barnumlives]

i have used the por-15 tank sealing kit before but it was on an extremely 5 gallon honda generator tank. after sloshing a section of chain around in it to knock loose any rust scale the step i added was to remove any remaining rust through electrolysis (google search: rust removal, electrolysis).

i then followed the por-15 tank sealing instructions exactly, particularly the parts about everything being perfectly dry prior to sealing and to make sure any ports/openings in the tank did not get sealed shut.

according to the por-15 information their product is impervious to anything you might introduce into the tank. with the proper surface prep the sealer should remain bonded to the tank's interior.

if you have a bricks and mortar paint store nearby that stocks por-15 products you may want to purchase the metal prep and degreaser in the one gallon size. invariably the pints are just enough for the project but leave little for the next time.

[930dreamer]

Back at it today, still can't get a piece of wire through. I'd like to try from the other end but can't locate it. I'll post some pics of the tank tomorrow. Note to self, bring a small flashlight tomorrow.

[mercmad6.3]

I have struggled with the buggers enough times to know that if you have any blockage at all it will cause problems.
I can also tell you that the only way to successfully clean one is to cut the top out of the tank and clean the entire inside.
The Return line is nearly always blocked. You MUST be able to get a wire right into the tank. If you can't ,throw the tank way because only by replacing the tube will you rectify the problem.
The return line is vital for both carbed and injected engines.
The worst problem apart from the blocked lines is the port for the flower pot supply becoming blocked . You can have 3/4 tank of fuel and nothing getting pumped because the feed is blocked off. Again,the only cure is cut open the tank and fix it.
To answer your question,by all means use the POR15 product. It works great,especially after the tank has been opened and welded shut.

[sal Escoto]

I followed instruction from link below for my fuel tank problem and it worked for me

http://www.ratwell.com/technical/FuelTankRestoration.html

Sal
76 300D

[DieselPaul]

Originally Posted by 930dreamer

I've been working on the tank in between everything else going on. I removed the strainer bolt/plug, that was a bear. I still can't get a piece of wire to go all the way through the return line. I've used a drill with the wire but it's a no-go at this time. The wire has muck on the end so I know it's a mess in there.

I used an air compressor to clear all the lines.

[930dreamer]

The tank went to be boiled, I'll check it out then it returns. I need to start looking for a coating kit.

[930dreamer]

The tank came back from the cleaner with the return line still plugged. Good help is hard to find these days. It's a friends tank so I didn't get involved in that area. I unplugged the return line finally, removed the old paint and primed. I still need to top coat and seal the inside. I used a brass wire wheel to remove the paint. Where did this Summer go?

[Benz Dr.]

Funny how the term '' flower pot '' caught on. Coined by yours truely.

I would NEVER coat one of these tanks. You're only asking for trouble. Most of those coatings will come off and make things ten times worse than before you started. Even a slightly dirty or rusty tank will eventually self clean through repeated fillings after it's been boiled out. You might have to clean the screens once in a while but that other stuff will clog everything andf then you will buy a new tank.

[930dreamer]

Thank you for the advice, I'll just top coat it and re-install.

[mercmad6.3]

I've never had any problems what so ever with modern fuels (high toluene content ) and Por 15's tank liner. In fact i even use it inside the water jackets on Ponton and W189 engines and the latest has been on the inside of a oil pan on a racer which was dinged and wouldn't stop leaking through pin holes.
As can be seen,heat doesn't affect it either.
i wouldn't ever bother with a dirty tank, because I dont' like being stranded on the side of a highway,freeway etc.

[hchinaski]

Originally Posted by barry123400

The exhaust hose from a vaccum cleaner can be utilized on a nice day to speed up the dry before coating.

This is not a safe idea. Someone on the old Mercedes Mailing List did this about 10-12 years ago and posted pictures of the aftermath of the explosion - a ballooned gas tank and and exploded vacuum cleaner.