I am currently restoring a '27 Tudor and the gas tank has a heavy tar-like deposit from old gas left in the tank. Will lacquer thinner poured into the tank and allowed to sit and soak dissolve the deposit or will it be a waste of good lacquer thinner? If not, what would work better?
Steam's the stuff when it comes to breaking down gas tank deposits. If you can find somebody with a machine that generates saturated steam (not a hot water pressure washer), that's the ticket.
Berryman's gasoline additive......used to be called Berryman's Chemtool. Available at most automotive supply stores and will dissolve old tar, gum and residues. Let it sit until you're sure it's clean then drain/flush with water. Blow dry with compressed air and shoot WD40 inside to prevent flash rust.
The only downside it that the Berryman's is sold in little bottles as a gasoline additive. It used to be available in quarts.
I have had good luck using lacquer thinner to remove tar-like deposits. Let it soak for several days and then drain and flush with more clean lacquer thinner. It will not remove rust..... only stuff left over from old gas.
I also soak carb. parts in lacquer thinner.....can no longer get the good old carb. cleaner here in Califunny.
I can tell you this for sure: modern alcohol fuels will break down "old type" fuel deposits. The older fuels would not dissolve their own deposits. Mistakenly referred to as shellac. The marina's around here went nuts when the change over occurred. The alcohol was dissolving the residue that collected on the walls of the boat fuel tanks. There was a huge run on fuel filters of any kind. The stuff would become a whiteish powder and raise hell with fuel systems. Didn't take long either. After a couple of months the problem went away as the tanks cleaned out.
Put a little new gas in let sit few days the other thing i found works is the gas additives or carb cleaner
I would try the lacquer thinner. I have done one Model A tank that had a lot of varnish in the tank. Put a gallon in and rocked the car back and forth, didn't want to pull tank, seemed to work.
Lacquer thinner results:
* Last night I poured 4 gallons of lacquer thinner in the tank.
* Then I jacked up the drivers side of the car.
* Violently rocked car sided to side.
* This morning I used a long handled blow gun, stuck it into the tank & thinner and made lots of bubbles.
* I drained & strained (w/an old T shirt) the thinner. Last night, the chunks of tar-like gum were BB sized. This morning the straining caught very few particles the size of pepper.
* The drained thinner was a dark brown color.
* Then, a quart of gas was poured into the tank and the leaning car was rocked and drained. Done again w/a gallon of gas, which drained clean.
* A glass bowl type filter/shut-off will be installed and run until I am convinced the thinner a success.
Last fall I took the gas tank from a '49 Chev to the radiator shop and had them clean and check it.
It had sat idle 10 years.
I also installed a new fuel line, since I had been down that road a few times before.
A week later when the owner drove it everything seemed fine. Three days later when he started it it bent push rods and stuck valves.
I did a valve job on it. Great, ran fine.
The following weekend the owner said the engine was kmaking some weird noises.
Three days later when I got there it wouldn't start but it broke a rocker and bent some more pushrods.
I took the engine out and had all the parts cleaned, including the carb (again) and the fuel pump. Had a hard time pounding the valves out of the head.
I insisted he buy a new gas tank. We cleaned the carb, fuel pump and blew out the new fuel line with carb cleaner.
Now after several months it starts, sounds and runs fine.
For model A Fords I remove the tank, clean the inside at the carwash, rinse it with a couple gallons of acetone mixed with MEK and a final rinse with Mineral spirits.
I also replace the fuel line.
You need to have the tank out so you can turn it over.
Do all the work near a water hose for in case you spill something on the outside of the painted tank.
I have not had a problem with an A after doing that.
yesterday I took the cylinder head off from a Triumph Spitfire.
It sat for two years because it needed a new wiring harness.
The owner installed a used harness and got it running.
The next day when he started it, it bent two push rods and broke two rocker arms.
If you are not going to change the gas every 6 months it's best to just drain the tank and use up or drain the carb and fuel line on cars that are just gonna sit for a year or more.