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Fuel tank cleaning/restoration

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NutmegCT

NutmegCT

Great Pumpkin
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There have been many conversations about this Tom and, all I can say with certainty is that no one is ambivalent about it - it seems like it either works brilliantly or fails catastrophically. Certainly at least with POR you must must must follow the instructions to the letter.

Having said that, do you need to do anything? is the tank rusty? I actually replaced the tank when I did the Midget but in retrospect it probably only needed a good clean.
 
As above, do you really need to line the tank or perhaps just clean it?

I have lined about a half dozen tanks with mixed results.
I have not used the MOSS kit so I cannot comment except to say it will be someone else's product with their name on it.
The Eastwood kit is almost certainly a re-packaged version of Kreem.
The POR kit should not be confused with POR-15 paint. The POR tank liner is a similar but more rubbery coating.

Kreem has a reputation for failing. However, the tanks I have used Kreem with are still lined. Kreem uses MEK for the solvent and it is not pleasant to deal with. Cosmetically, Kreem coatings look good initially but rapidly turn redish amber from fuel exposure.

POR kits are the easiest to deal with chemically. The coating also looks wonderful as it has a metallic appearance that takes a while to discolor. However, POR is the only coating I have had fail. After about 4 years the coating flaked off the inside of the left hand tank on my Mini and plugged the fuel supply to the pump. Unfortunately... where the coating failed... it failed. When I needed to get the remaining POR coating off the tank it was stuck rather well. I have used POR products before so I knew the prep work had to be done right... but it failed anyway. It was so hard to strip that tank to remove the POR that I will probably not use it again in the future.

When I recoated the tank where I removed the POR I used Red Kote following the advice of a friend. He has used Red Kote for years without a failure. I am probably 3 years into my Red Kote tank without problems.

My suggestion... unless the tank has pinhole leaks or some other reason to require lining... just clean the tank. Don't line.
 
I have used the POR-15 system on several tanks with total success so far. The first one was done in 2002 and is still holding. The last one was about 5 years ago. YMMV of course.
 
I used POR-15, but have no miles on the tank. I used a shop vac to pull air through the tank for a good hour, in an attempt to make sure it was dry. I also "danced" a torch on the outside of the tank to help get things warm. (But did not want to get the metal hot enough to rust.) The hardest part of the instructions, in my opinion, are that once you prep the tank for paint (with wet stuff) you have to paint soon afterwards (on a bone-dry tank) - i.e. get all the water out of the tank as fast as possible. With the baffles inside the tank, it is impossible to see if all the water is out.

I also had a hard time getting the paint mixed. I vigorously mixed for over 15 minutes, but still had some streaking in the paint. In hindsight, I should have used a power drill to mix.

The final result looks purdy!
 
Thanks gentlemen. I guess my first question now is ... how do you determine whether the tank actually needs work?

If I look down inside, it's very clean for the first 12 to 15 inches or so, but below that I see what looks like some rusty brown "gunk" near the bottom of the tank. And of course because of the baffles, I can't really see much other than just below the filling hole.

TM
 
Everyone will have their own preferred procedures for how to clean the inside of a tank. Most can be used one after another until you get the results you want.

In the case of a rusty tank with brown goo in the bottom, I suggest the following possibilities.


  • Drain the tank of gas. Rinse with water. Fill with a gallon of strong caustic cleaner (I like ZEP Industrial Degreaser from the home center). Once you put the cleaner in the tank throw in handfuls of nuts, bolts, chain, washers, rocks, gravel, etc. and shake the tank around every few minutes. After each shaking session, put the tank to rest in a new position. Do that over and over for a day then drain the tank and rinse it with clean water.
  • If goo remains in the tank, buy a gallon of strong paint stripper. Pour that and the nuts, bolts, etc. in the tank again and repeat the shaking sequence. As before, flush with water and perhaps more of the caustic cleaner to remove the paint stripper.
  • By now, one of the methods above should have removed fuel gum and the tank should be clean. If it is rusty you have a couple of options.
  • Repeat the sloshing with nuts, bolts, etc. but this time use a half gallon of phosphoric acid. When you are done the tank should be metallic inside with only a few rust spots if any. Rinse with lots of fresh water, then apply heat to the tank to dry it as quickly as possible to minimize flash and surface rust.
  • If you don't like the acid method this next one is fun. Fill the tank 1/3 full of water and put it on a propane grille. Heat the water to boiling so steam is coming out of the filler neck. Keep topping up the water as necessary but keep boiling all day then drain the tank and rinse with clean water.

Now determine if you NEED to line the tank. Fill the tank with water and put it in a place resting on cardboard or paper where any pinhole leaks or drips will be observed as spots on the paper.
 
Thanks Doug. I'll need to proceed extra carefully, as the TD has an external tank which is painted body color.

I think my next step is grab some of that gunk and see what it is.
 
The following is probably unrelated to what you'll find in your tank but is the weirdest thing I found in one.

My father-in-law picked up a VW based kit car which had been sitting in a warehouse for 20+ years. The fuel had turned into "stuff" that looked something like charcoal briquettes made from burnt marshmallows. Some of it was light, porous and fluffy. The stuff against the walls of the tank was tough like petrified tar. I used a gallon of paint stripper in the tank along with the nuts and bolts I mentioned earlier and sloshed the tank daily for a week or more to clean it out. Fuel can turn into some weird stuff after decades of sitting.
 
Gak. Fortunately no burnt marshmallows in my tank - at least what I could see.

I did find flakes of rust at the bottom of the tank when I took the sample today, so I assume cleaning is necessary.

TM
 
I will also point out that there are gas tank restoration companies in pretty much every major community.
 
JPSmit said:
I will also point out that there are gas tank restoration companies in pretty much every major community.
Click to expand...

That is good to know.

So, how do you determine when it's finally time to clean the tank? Is finding rust flakes at the bottom the "signal"? Or just ignore it if the rest of the tank looks relatively clean (rust free), and let the fuel filters do the work?

TM
 
Flaking rust is not necessarily a problem at all. My preference in such situations would be to put a large, coarse, transparent filter inline from the tank discharge port and the fuel pump. Watch the filter. You'll note when it is filling up with scale. Change the filter when it bothers you. On our Mini and GT6 I have one of the glass bodied "bling" gas filters (available from most parts stores) which can be cleaned and rebuilt when it starts to fill up.

I would save major cleaning until fuel delivery from the tank becomes a problem (indicating the pickup screen in the tank is blocked).

I would save lining a tank until you actually have a leak requiring attention.
 
Doug - thanks for the suggestions. I'm actually not familiar with that type of inline filter you describe, that can be cleaned and rebuilt. I've only seen the "throw away" clear plastic filters, like this:

View attachment 49636

Can you give me a link to the one you describe?

Tom M.
 
The plastic filters with paper elements work but they can plug up faster than you would like. I do use the type of filter Tom posted a picture of but I typically put them right before the carbs to catch fine sediment. I buy them off eBay to get the best price. Search eBay Motors with keywords "plastic vw fuel filter". You will find a lot of vendors sell them in bundles of 5 or more which makes them affordable. For reference, a local parts store may charge $5 or more/each for the same filter.

David has posted a link for the type of filter I was suggesting. It has a coarse, nylon mesh screen for a filter element. It stops the big stuff to protect the fuel pump and can be taken apart to clean or replace the mesh. Most parts stores sell them under a variety of brand names. Advance Auto sells them as products from "Spectre" (link below).

https://shop.advanceautoparts.com/p...369/22905603-P?searchTerm=spectre+fuel+filter
 
Thanks. I think I'll start with a simple paper filter at the fuel pump on the firewall.

View attachment 49639

After a while that should show me how much rust and crud has been reaching the pump. The SU pump has its own mesh filter, as do the two SU carbs - but a clear filter will let me see what's coming from the tank.

TM
 
Keep in mind that pumps "push" better than "pull". If the paper filter placed before the pump starts to load up, fuel delivery will drop off quickly. Keep a spare filter with you just in case.
 
I chickened out on cutting the original copper fuel line or monkeying with the compression fitting, so I put the filter between pump and carbs. We shall see what we shall see ...

View attachment 49640
 
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