Boil-out vr. Acid on varnished tank by radiator shop

[brucepine]

Most large hardware stores should have MEK in the paint department.   About $10.00/gal.

[50Plymouth]

I ended up dropping the tank off at a shop that had the best local reputation and is used by the street rod \ restoration shop people in that city. They will take their time, boil it out, possibly additional cleaning out if rust aside from varnish and the probably coat it. Should be $135. I was looking at a supposedly good tank on ebay but seller stated 'had surface rust after powerwashing and needed lining'. Plus, my wife doesn't get happy when I mess with certain chemicals  :) I'll see how it goes and decide whether to do another tank I have with the same problems myself or not. I figure with chemical costs and them doing the work this may be okay..

I may yet try something like this MEK solution on my other tank though.. How expensive is that stuff?

[brucepine]

I too have cleaned several varnish and old gas gunk coated fuel tanks.  I have found straight MEK to be the best for tank sloshing.  I always have removed the tank, removed the fuel gauge sending unit,and if there are NO built in baffels I put about 5 ft. of 1/4" chain in the tank.  Tie a retreaval wire to the chain end and slosh by hand so that the chain will abrade the bottom surface.  Several dumpings of the tank are generally needed, but the easily loosened rust is removed also.

[Carla]

Ryan,

I didn't originate that solvent/agitation method of cleaning up old fuel tanks, its a common method which was used back in the '60's, that I know of, and probably for quite a few years before that.

Back in the '60's, I had a number of friends who made a hobby pursuit of finding old cars in back yards, etc., when they could be gotten for scrap-value or for free (you really want that old junk car thats been sitting here since it stopped running back during the war????....sure, if you will haul it away, you're welcome to it.....theres a bunch of other old junk in the garage and the basement you can have, too if you want) and getting them back into good running order.

Sometimes, this meant collecting up several cars of one make/approx year, and using parts from several to assemble one functional one. (times change, to be sure......my cousin got a '34 Ford two door in near-perfect original condition, except that it ran in a cloud of oil-smoke from broken rings.....just for hauling it away....and what would that car be worth on the collectors' market today?)

Solvent-cleaning the varnish from the fuel tank was just one of several things which had to be done, along with cleaning out and rebuilding the brake system, having the oil-sump off the engine and cleaning the congealed sludge out of the oil pump pickup screen, re-packing front wheel bearings, etc.

Later, when I worked awhile with a group of truck mechanics, I brought a number of cars and trucks back from long-term 'hibernation' myself as a 'side-line' so to speak.

To answer your question, yes, I have used that process to clean somewhere around thirty-odd fuel tanks in various and sundry old vehicles, and the technique worked nicely.......except that some of the tanks were rust-pitted, and would leak, so they'd have to come out and have patches soldered on, or be replaced with a good tank, if one was available.

I should have mentioned another solvent which works well for removing gasoline varnish, albeit the stuff is a bit pricey......its a carburetter cleaning solvent, 'Berryman's Chemtool'. There may be similar products available under different trade-names in other areas, you can ask at any automotive supply house.

With the tank out of the car, you could use any source of vibration, such as tying the tank down in the bed of a truck thats run over rough roads or for long distances, as a way to agitate the solvent in the tank.

cheers

Carla

[50Plymouth]

Thanks for the informative reply! The tank is indeed out of the car. It had about 8 gallons of nice old orange smelly gas.
I will steer clear of the shop using acids then... I fear this may get pricey (I actually have two tanks to repair) the initial cleaning is only around $70-75 but if they want to sandblast, yikes$$$. I have to drive 1 1/2 just to find a shop that was willing to do it (I'm rural)

Have you done the in-tank bubbler approach yourself? Do the plugs on 50+ year old tanks ever actually come out?

I will report my findings, expense, and how things go here should others be searching before their shop visit.

[Carla]

Ryan,

If you already have the tank out of the car, taking it to a radiator shop who uses a mild hot caustic tank to clean tanks could be a good idea.

Taking it to someone who would use an acid, however dilute, is a really bad idea, particularly if they use a 'tank liner' product after etching the metal thin in spots.As a generality, the so-called 'tank liner' products are a 'scam', intended for the same general type of gullible car owners who might buy 'engine overhaul in a can' additive oil products.

If the problem is simply fuel varnish in the tank, you can clean the tank 'in situ' without removing it from the car.......I've cleaned a number of badly varnished fuel tanks in situ, with good results. Some of the worst were cars or trucks which had a nearly full tank of gasoline when stored away, which either turned into a thick coating of varnish or degraded into a semi-fluid substance resembling Permatex.

(speaking of Permatex, here's a little bit of trivia from the past........how many of you remember the old Permatex adverts in the various automotive trade magazines?.......the 'Remember, Permatex Pete says' ads.......as your trivia for today, what did 'Permatex Pete' say?......a hint....it was a bit of really good advice)

To remove fuel varnish from the tank without removing the tank, simply drain the tank, put in two or three gallons of fresh gasoline, and add a gallon each of acetone and methyl-ethyl-ketone (MEK), which should be readily available at any good hardware or painters supply house. Lacquer thinner will work nearly as well, and might be more conveniently available.

Then run a length of air hose into the tank, enough that the hose end will lay on the very bottom of the tank. Use an air regulator in the line to cut the air pressure down to the 20-40 psi range, and 'bubble' or 'agitate' the fuel/solvent mixture in the tank. Obviously, do this outside, not in a building or other enclosed area, as the air exiting the tank filler will bring flammable fumes with it, likewise, take care to avoid breathing the fumes.

After letting the agitated solvent work for as long as you have patience for, ideally several days time, put a good drain pan under the tank and open the drain. The material which will emerge will be somewhat disgusting smelling stuff, so brace yourself for a mildly unpleasant experience. A paint safety mask and good safety gloves will help.

Put the drain plug back in and 'do a rinse cycle' with two or three gallons of fresh gasoline, agitating it with the low-pressure air for a few hours time. Drain the tank again, and note that the gasoline should be very nearly clean this time.

If you get a lot of rust flakes in the drained fuel/solvent mix, then you may have a tank which has sat with a bit of water in it, and has rust pitting in the tank bottom. Sometimes there will be little rust-pitted spots in which the tank is actually rusted through and will leak, if so, then there is nothing for it but to have the tank out and solder patches over the rust-pitted spots. (you may 'get lucky' on a temporary basis, by using patches cut from thin brass shim stock, along with 'Devcon Plastic Steel' epoxy putty, applied after sanding the area to clean bare steel)

If you elect to have the tank out and solder patches over rust-pitted areas, this  will work well, but remember that you must arrange suitable plugs so that you can fill the tank with water before having a torch flame anywhere near it. The heat of a torch flame will drive hydrocarbon residue off the metal of an empty tank interior to the point at which it will form an explosive mixture, which will detonate literally like blasting-powder.

This is no joke. I was able to demonstrate this phenomena to some friends, some years ago, when brazing up some split seams at the bottom of a 40-ish gallon truck fuel tank. I had the tank upside down, with the filler and other openings plugged, and the tank completely filled with water to within 1/4 inch of the 'top'. As I was repairing the seam, I'd occasionally wave the torch flame over the  open drain plug hole, whereupon the little bit of explosive mixture formed in the very little bit of tank area above the water level would detonate with a loud 'pop'.

Oh, well, thats probably a lot more than you really wanted to know, isn't it?

Anyway, really, seriously, don't etch a tank with acid, and don't use 'liner' products. Some people have 'gotten lucky' with liner products, some have had the stuff turn into a horrible mess in the tank and promptly clog the fuel line solid....once the tank is clean, the gasoline itself is an excellent rust inhibitor, and will itself keep the tank clean inside and free from rust. If you must store the car away for awhile, drain the tank, and leave the tank drain plug out so that any water which forms from condensation will drain out.

cheers

Carla

[50Plymouth]

I'm taking my plymouths tank to a radiator shop tomorrow. I found some shops that do a traditional "boil out" (though I'm not sure what exact chemicals\process that means) and other radiator shops that want to use muriatic acid followed by a liner.. I'm afraid liners would be a problem with what ever metal screen is in the middle of the '50 tank and that pickup tube.

Any experiences between the two methods or pro's\con's.. I've heard some people praise acid and others say it doesn't match a boil-out. At this point I'm not ready to try the POR-15 kits myself. I want someone else to use the dangerous chemicals  :) and do it right.

Ryan