How To Inspect Fuel Tank For Rust And Other Crud

[Vanagonsgoslow]

I derusted my 1970 Porsche 914’s fuel tank with white distilled vinegar. It’s cheaper than those de-rusting kit chemicals and easier and safer to use. Search YouTube for videos on cleaning motorcycle gas tanks, which is how I learned about it. The results were remarkable. The tank looked like new inside when I was done.

[AndyBees]

As I stated previously, I did the tank sealer on my 83 in 1992.

The kit came with everything necessary to do the job (took two kits as these were motor cycle tank kits).

- I used gravels to rattle around inside the tank to break loose flakes.
- I rinsed with water and repeated numerous times.
- I put the chemical inside and let it set per instructions
- I dumped the chemical (full tank)
- I rinsed with water numerous times per instructions
- Then I used Acetone to absorb the balance of water (two or three rinses)
- Then I used a hair dryer to blow-dry
- Then I added the coating per instructions which required dumping out after x number of minutes
- Then followed with another coating to finish. There was coating left over.

No! I do not recommend this process for these reasons.

1. It is a hard job.
2. I don't like chemicals
3. I doubt my back could stand all the lifting and tumbling. (oh, that's why there's a #1.)
4. And, more important, there are two screens inside. One is for fuel going to the engine and the other is for fuel retuning to the tank. I did not know this in 1992. I was lucky those screens were not totally plugged.

No, you are not going to damage the tank cleaning out the rust. It is very strong.

The tanks in Westys are the same as tanks in Tin-tops with the exception of early models vs later models relating to the fill spout hole.

A motorcycle jack makes removing and installing a tank much easier than man-handling it.

Oh, and the tank in the '83 has held up just fine all these years. I did the tank on my Ford 8N Tractor with that left-over coating........ over 30 years ago and it still has the white coating on it.

My '83 has a pre-filter which has always worked just fine.
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'84 Vanagon Tin-top, ALH TDI, two trips to Alaska, 2014 & 16. 1989 Tin-top unmolested.
1983 Air-cool, 225k miles, 180k miles mine, seven trips to Alaska from 1986 thru 2003. 1975 Bay hopeful.

[raygreenwood]

Don't coat/seal the inside of the tank. Unless you have pinhole rust through, it's not necessary or guaranteed to work. The POR tank sealants have had many problems. Just do some searching in other forums.

The gist is to get rid of all crusty rust and then convert what rust is left to iron phosphate with a rust converter that has phosphoric acid in it. This black iron phosphate....does not rust. Once you get it to that stage, just keep your gas tank minimum half full and oc asionally treat with gas line de-satering treatments like Heet and you will never have rust again.

Do not use bicycle chains and items like that. Whenever you scratch steel, it rusts faster at the scratches.

The very best "de-ruster" is muriatic acid or a very high level caustic....both will dissolve rust down to bare metal.

You can either take your tank to a gas tank or radiator shop and have it boiled in caustic which wi totally deduct it or use muriatic acid if you are willing to do it right or buy some phosphoric acid rust remover which is much easier and safer than muriatic acid for those not experienced in chemical handling.

So, you can buy two different easy to get strengths of phosphoric acid. 45% and 30%.
If you are trying to "de-rust" all of the crusty rust....buy the 45% and use it straight. This will take it down to bare metal if you leave it in long enough.

But, the problem is that once you remove ALL of the rust, there is nothing left for a more dilute form of phosphoric acid to convert go iron phosphate.

Typically if the phosphoric acid is just a mix of phosphoric acid and water at 45% strength, this is string enough to cause what is called hydrogen embrittlement at the surface. So rinse it well and let it sit for a day or two. This will cause flash rust all over the inside surface....which is what you want....because its typically only a handful of microns thick and will be uniform.

Then you take the rest of your 45%, do the math and dilute down to ~25-30%......throw that in, sloshing it around well and drain it out. Do not rinse. Let it sit 24 hours to dry and you will see the bluish black iron phosphate layer form. This is permanent rust control.

Ray

[do.dah]

I'm with you on that.
There's some threads here, about people retrofitting a strainer/filter before the pump,, usually without much satisfaction.

Mansi usta sell a pre-pump strainer. I got it, installed it and have had no issues.
I think what I catch from the other threads about pre-pump filter/strainers, is that most of what you can get, is a filter, which doesn't seem to play well with the fuel system?

[SoquelDude]

[jlrftype7]

[SoquelDude]

So, I'm convinced the 30+ year-old tank has rust and other crap in it. That will clog not just the filter but the pump as well over time. I suppose it's possible that once the filter gets too clogged, it will fail, and crap will seep out to the injectors.

So, for now, I plan to change the filter more often. I think the recommended time to change is 30K miles. I'm not sure when the PO last changed the filter, but when I changed it looked pretty old. So, for noe, I'll stay with a 5K interval.

The trouble is that the filter is downstream from the pump, which I recently changed as well. It cavitates sometimes, so I'm guessing the crap in the line is starving it. Note that it isn't cavitating/whining as much as the old pump, but without a pre-filter, it's only a matter of time before the pump starts to clog.

I'm not hot for the idea of repairing/rust-proofing the old tank for fear of stressing the old metal and causing leaks.

The ultimate solution I can think of is to replace the tank and the lines. I've seen the horror stories about seating the sensor unit on a new tank, so I want to do some more due diligence and look up posts from other westy folks who have changed their tanks.

Thanks for all of the great into!
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'90 Vanagon Westy GL, AT, EJ22E conversion (1993 2.2L Legacy Engine)

[vanis13]

[SoquelDude]

[SoquelDude]

[AndyBees]

[syncrodoka]

You can't seal a 2wd gas tank, you are more likely to mess up the tank than make it better. There are parts inside you are likely to damage. Replacement is the only real option.

From the gallery

[Xevin]

Por-15 is dicey. I know more failures with it delaminating and clogging than long term success. I’m sure it’s been successful. You might call Old Volks down the street from you and see if they know of a radiator shop locally that can inspect and clean up without a coating. Some people have had success with a bicycle chain (or similar) and diesel fuel shaking around to knock off the crusty stuff. Do your research as you are. Just something to investigate. I have no idea if any of my suggestions are more cost effective than buying a new tank or used OEM tank
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Keep on Busin'

[hardway]

If your original tank is in good condition it is a better tank than the replacements. Getting the level sender to seal with the replacement tanks requires some finesse. They just don't fit well. They also just don't have the same internal components. Sometimes benign neglect achieves a better outcome than good intentions. Sometimes you just have to replace the tank and deal with it's shortcomings.

[SoquelDude]

[SoquelDude]

[SoquelDude]

[pbrown]

POR15 has a kit for tanks. I've used it with vintage motorcycle tanks. It's handy when you don't want to or can't replace the tank.

https://por15.com/products/fuel-tank-repair-kit
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Patrick Brown

1986 Westy Syncro EJ25
Flickr --> https://flic.kr/s/aHsmQNUXEF

[hardway]

If you take the tank out and remove the fuel level sending unit you can see most of the inside pretty good. But just blowing backwards through the filter when you change it should give you a good idea of how much and what is coming out of the tank.

[Xevin]

Odd how the Vanagon’s improvements over the Bay and Split failed so bad with the fuel tank.
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Keep on Busin'