Just wondering, has anyone ever used muriatic acid to clean a tank? I've done this with motorcycle tanks a couple times but never something as large as an auto tank. I know the dangers of it so don't tell me I'm gonna die. What are you guy's other methods?

 

Something that strong can really hurt the plating in the tank, it can pull the tin from the terne plating causing it to flake off, think late model ford diesel delamination due to high alkaline additives and improperly blended bio's.. A water soluble cleaner or degreaser is best.

 

I agree w/Matt. That stuff is too strong for cleaning a plated tank. How do you know it needs cleaned? If it is rust you are battling then you need something mechanical in there to knock it loose. I tried a chain, but it wasn't as effective as I'd hoped and I did it 4 times, shaking/sloshing the tank as long as my brother and I could each time. We then poured out the 2 gallons of gas, added another 2 and did it again, 4 times in all. And it didn't get anywhere near all the rust. So, I've had to run two filters back-to-back and change them or the carb plugs. But, it is now a lot better after almost 2 years and a couple thousand miles.

 

I've done this once. It wasn't a plated tank, nor rust that I was dealing with. The car had sat for many years, and the gas evaporated away, leaving a ~3/8" thick layer tar-like coating on the bottom of the tank, which kept oozing it's way into the pickup tube. Nothing else would liquify the gunk enough to get it out, so we tried the acid-based A/C coil cleaner concentrate, which finally did the trick.

 

I have never done it, but one guy I spoke with said that after he drains the tank and rinses it out, he pours in a quart or two of naval jelly and throws a bunch of hardware (mainly hex nuts) of various sizes and then rolls the tank around letting the hardware slide, tumble, and bang around inside to knock loose any scale, etc.

But in the long run, why bother? Even if you can clean the inside, you will still have an old rusted tank that is going to continue to rust. New tanks are $120. I would just replace it. Also, when you pull the old tank, there is a good chance that you will find rust holes in the top where the two strips are that cushion the tank against the frame cross members.

There are (or used to be) places that would clean a gas tank and then epoxy coat the inside. This is really only useful on something really old and rare where you can't get a new tank. They charge more than the cost of a tank for their service.

 

I would have to agree with Jim. I have an in-line filter before it gets to my carb, change it once a month and its still full of sludge. PO had removed the rear tank. Im putting the system back together with two new tanks.

My truck is a daily driver, put about 1500 miles a month on her. The tanks were each about 85.00 w/shipping from Midwest Auto parts online. After putting in a rebuilt carb and messing with fuel filter changes on the side of the road like the flat tire scene in Christmas story I think the money is well worth it.

 

Vote #3, get a new tank.

 

This tank sealer kit from POR-15 has worked great for me, used it four or five times. In 15+ years since the first one, no sign of any rust recurrence or peeling...

However, over the years the kit price keeps rising (currently $77), and it's a fair amount of work to do correctly, so if you can get a new tank for only $120 I would just do that.

 

I went through this with my truck. I ended up pulling the tanks and cleaning them with acetone.

I used this stuff.

Damon Industries Red-Kote Gas Tank Liner

 

If you are wanting to remove the old varnish from evaporated gas, then I'd a carb cleaner that is designed to remove it, it would probably work best if you used something to agitate it like mentioned in the other messages. The cheapest would be to buy a couple of store brand aerosol cans at the chain auto parts for @ $3.00 each. I agree with the others-if its rust, then why put a bandaid on it, go ahead and replace the tank.