cleaning out old fuel tank, is it time to give up?

[tevake]

Aloha, As I shared in an earlier thread I am into rehabbing a 1980 SC targa. it was in storage for ten years, so needs a real going over. Its coming along pretty well. one of the parts I have been working on is trying to get the fuel tank cleaned out. Its been flushed with all types of solvents, blasted with water, even had scoops of gravel adjitated all around to scour the insides out. then I put in some fuel and a bunch of motor oil to keep from rusting while refinishing the outsides.
That has finally come together after a first coating with a supposedly rubberized undercoating. which ended up not drying and having to be removed [mineral spirits is the way to go for undercoat removal]
Ended up refinishing with spray on truck bed liner. Came out looking good.
So today was to be reinstall day. After a bit of a flush with clean fuel to remove the oil.
Well I have flushed and flushed and am still getting very funky looking fuel coming out!!!


In researching here there is mention of taking it to a radiator shop to flush it with some acid wash ? There are no such shops on Kauai. I also came across a tank coating by the folks that make POR 15. Has anyone here used this coating or others with good results??

Is it time to give up on this tank, and order a new one?? OUCH$$$

[ossiblue]

My first question: Is the coloring in the jar due to sediments? You may wish to let the jar sit for a day or two and see if it clears up and there are solids on the bottom.

Someone, I'm sure, knows what kind of acid is used to flush radiators. Possibly it may be available in another form where you can mix a mild solution and flush the tank yourself. I'm thinking along the lines of phosphoric acid which can be found in other products, for example. Just a thought.

Finally, your tank has a swirl pot in the bottom where the fuel outlet/return lines are. I'd research any product that is used to seal the tank as it may clog the lines in the swirl pot. I'm not familiar with the POR-15 product, but others have used it. If it is a thin liquid that bonds to metal you probably won't have a problem. If it is a thick coating, that could be an area of concern. Just a heads up. Others will chime in with direct experience.

Lots of people have had tanks like yours refurbed, so there's likely an easy solution. If it's the radiator shop, however, you may have to consider an inter-island shipment to a location that can do the work--still cheaper than a new tank, but maybe comparable to a used one. Something else to consider.

[porsche930dude]

well id say if your not getting chunks coming out run it. add a cheap inline filter at the exit of the tank before the pump and change it after a while. just wash it out as best you you can before you put it in. I dont really know though. I just have alot of experience with small engines

[tevake]

Thanks L J for the heads up about the swirl pot, good to know, Yes the discoloration is tiny rust particles and tint. the particles do settle in a short time.
I would like to hear if anyone has had luck with coatings.
Or what kind of treatment might help. I did turn up that some have used chain to scour the insides of their tank. sounds like a better idea than the gravel. much easier to remove.

Thanks Richard

[GWN7]

The gas tank on my 69 sat for 16 years with about 7 gals of the nastiest fuel in it when I acquired it.

I drained it, took it to a rad shop. They put it in a tank of hot caustic soda to clean it out. Then they coated it twice with the POR 15 treatment. (Coated and let dry. Then re-coated.)

The owner said it's the only way they know of to stop the rust.

They have plugs for the outlet holes and the sending unit. Pour the POR 15 mix in, then cap the spout end. Slosh the mix around rotating the tank to coat all surfaces. Pour out the extra POR 15. Wait a day and recoat. Wait two days before adding gas.

That was two years ago....So far so good.

[pioneer1]

Aloha: POR gas tank repair kit uses a phosphoric wash and cleaner before the sealer is used. When I did a tank on a '51 MG I threw in a handfull of sharp edged 3/4" gravel,rotated the tank over and over to break off any rust and clean the inside, and emptied the stones. The gas tank is still sealed 10 years later.

[scotricker]

Awesome back yard! .... we'll be right over to check the gas tank...

[ossiblue]

Richard,

Here's a link to some pictures of the swirl pot inside your tank:
1973 911-T (CIS) Fuel Tank Exposed

Again, the concern would be that a thick coating would enter the pot through the hole in the top and eventually clog the inlets which are very narrow slits around the center filter hole (look carefully at post #11 in the link and you can see the slit as a black line in the metal piece around the center hole), or the return line which is along the right side of the pot, in the pictures. The posted uses of POR-15 were on tanks without this swirl pot. Hopefully, someone who has repaired a tank like yours will chime in soon.

[E Sully]

Part #: PEL-TMP-9710

[Tsunamiboy]

There are reproduction tanks on the market, I think about $549. I took my tank to a reputable rad shop and they did a great job but it cost $350 They cut the tank open, cleaned, coated and welded it back up. If I had it to do again I would buy the reproduction.

[tevake]

Lots of useful info coming out, especially the split tank for the inside view. thanks paulo for the sacrifice.
L.J. I share your concern about plugging up the drain and return lines.
It does sound like the POR coating can do the job. At least on a more simple designed tank.
Has anyone done this treatment on a tank with the swirl pot with good results??

Pool party at my house when we get this done!!

Mahalo Richard

[tevake]

Up date from tech. guy at POR 15 customer support . He said that the product is not formulated to bond to plastics, and would sooner or later come off and end up in the lines and filter.
So I am thinking about pouring a bunch of Ospho.[ A brand name for phosphoric acid.]
Into the tank, then give it the slosh test. to see what comes out after that??
A last ditch try to save this tank. Before ordering one from our host. @ $ 449.
Any thoughts??
Richard

[dshepp806]

Order/install the new piece.

Best,

Doyle

[GWN7]

Originally Posted by tevake

Up date from tech. guy at POR 15 customer support . He said that the product is not formulated to bond to plastics, and would sooner or later come off and end up in the lines and filter.
So I am thinking about pouring a bunch of Ospho.[ A brand name for phosphoric acid.]
Into the tank, then give it the slosh test. to see what comes out after that??
A last ditch try to save this tank. Before ordering one from our host. @ $ 449.
Any thoughts??
Richard

Isn't your tank metal? If it won't stick to the plastic cup inside then that's a good thing. Rattle a chain inside. Ospho it. Then POR 15. Put a inline filter just after the tank and your good to go.