How to test a used gas tank?

[greaseball]

Hey guys, dumb question but here it goes-
  Got a used gas tank, looks pretty nice but when I try to blow through the gas line hole it seems like it could be restricted. The sender is out (obviously) and it looks OK inside but... I'm not sure.

Is there some "free" way I could test it? Water or something? I know I should take it to a shop and have them boil it out but... not if I don't have to.
Thanks

[terry_208]

Can you run a wire through the bung or maybe a drill bit or is there a built-in restriction? 

[RICH MUISE]

When I did a bunch of welding on my new gas tank for the in-tank fuel pump, I used a cheap lacquer thinner to clean it out and check for leaks. I added some blue Dykem to the laquer thinner to add visibility should there have been a leak. They do make a gas tank clean-out kit. I think por-15 has one. If it's rusty inside, I personally wouldn't bother with it. New tanks from Auto City Classic aren't that expensive. You don't want that crap in your fuel system.

[Wirenut]

No restrictor just an open port, you can run a wire or drill bit through it to clear obstruction. The tank probably has enough scale and rust particles that have collected around the opening, so what you have in mind will get some flow and movement through it but if there is enough rust inside to plug the hole it would be worth looking at a replacement instead of a repair. In most cases the repair is a short term fix.

[Ford Blue blood]

If you want to keep the tank it can be cleaned.  I have used thinner quite successfully to clean many tanks.  First it gets rid of any residual gas that could be trapped in flacky rust or tar from old gas.  It will dry with no fumes and allow welding without the fear of going to the hospital.  I use a stranded cable (choke/throttle/emergency brake) to run into the pick up tube.  If it is clogged situate the tank so you can put a funnel on the outlet and fill it with thinner.  Keep pushing and soon there will be a break through.  Then a round brush to scrub it.  Next put a gallon of soapy water (dawn dish soap) and gravel in and shake the daylights out of it.  Clean and dry (hair dryer works well).  Then pore a bottle of rust converter in and rotate the tank to ensure all areas are wet.  Dry for a couple of days then put in the tank liner of choice.

The tank in my 36 has been in service since 1980 with no issues after using the above method.

[59meteor]

Like Rich, I bought a brand new gas tank for my 59, from Auto City Classic, in Minnesota, for under 200 bucks, I just couldn`t deal with trying to make a 60+ year old, dented and rusty tank usable. I know people that have spent more on cleaning and coating the old tank t han they could have bought a new one for. I am sure that there are some old cars that new tanks are not available for, but luckily, 50s Fords are not in that group.

[greaseball]

Thanks for the helpful replies guys! This board is really great.

So, it sounds like I need to get some thinner in it if I plan on keeping the tank I have-
I shook it up the other day and there's more rust flakes inside than I thought. Couldn't shake 'em out either.
I can get a length of wire down the outlet maybe 10 inches inches before it jams... I was trying to use PB blaster ('cause it's a rusted bolt inside, right? Ummmm...), don't know why I didn't think of thinner- Much better idea.

If I were to go the "new tank" route (thanks 59meteor for telling me about Auto City Classic, seems a windshield from them might be a good idea also,), how much "prep work" do you guys recommend?
'Cause the factory did none, right?

I don't want this to be a "forever" project (I'm not a builder,) I just want a DRIVER!

[59meteor]

I have had my new Auco City gas tank in my 59 for 2 years now, it looks to have some coating, (maybe galvanized?), and still looks like new from the outside, and shining a flashlight into the filler neck, looks perfect inside as well. I did`t do any actual "prep" work to the tank, although I did have to tweak the filler neck a bit to center it in gas door opening. When I ordered the tank, I also ordered a new sending unit and tank straps, the sender works fine, but the straps did not work, at least for my 59, they had different mounting ends as the front, so I just cleaned and painted my old straps. And I also bought my new windshield from Auto City, none of my local glass shops could source a new windshield from their normal sources. I also bought the aluminum radiator from Auto City too. They were great to deal with.

[thomasso]

My tank was not rusted, but it had some dents plus I didn't want an  after mkt. tank.  Cut the whole top out with a saber saw about two lnches from edges.  Fixed the dents and wire welded the top back.  Applied penetrating Loctite to the welds.  Six, eight years ago, no leaks yet. Of course I could see a lot better then to weld.

[RICH MUISE]

Their gas tanks have an (optional?) Nitern finish which holds up great...mine is 6 years now. That Nitern finish I'm assuming is what made the tank weld up so nice when I welded in the recessed mounting "box" for my in-tank fuel pump. I don't remember having an issue with their straps, but I did get rid of the "J" hooks/bolts and replaced them with some eye bolts rotating on a shaft (tubing slid over bolt).........much easier to deal with.

[59meteor]

Rich, those eyebolts are a great idea! I retained the factory J bolts, and I trimmed  the end of the loop, since it was uncomfortably close to the top of the tank. As for the tank straps themselves, maybe a 57 is different, but on my 59,the stock straps have a bent hook at the front, which slips inside a slot at the front of a crossmember that runs side to side. The new straps had a hole in the front, and came with long "stovebolts", that I had no idea what their purpose was for. The new straps were too short to put a bent hook into, which is why I reused the original straps. Can you post a photo of how the front of your straps are attached?

[RICH MUISE]

Not sure I can get under there to take a pic......I'll try later......old age thing. That pic above was taken just a few weeks ago when I was changing the gear oil in the differential to add a friction modifier. Looking at that pic, the strap appears to be painted, which I wouldn't have done to new ss straps, so maybe I had the same issue as you.!?

[greaseball]

Well, I've had thinner in it for a while now, but every time I try to push my straightened coat-hanger through I seem to get blocked, maybe 10 inches in. Was thinking of trying to use compressed air on it...

(Mainly because...)
When we (Grandpa, brother and I) pushed my '57 out of the hog barn, Grandpa disconnected the fuel line (at the tank and the carb,) then put the air nozzle up to the disconnected fuel line. With the compressor's air-pressure he cleared the line of about 8-10 inches of sludge? Crud? (solidified old gas) which shot out of the fuel line with a resounding "ping" which I hope to always remember...

[RICH MUISE]

Just make sure the tank is not sealed off before applying air pressure.