Topic: Do we need to rethink how we line gas tanks because of modern gas/ethenol?

[ntm1974]

I cleaned my tank with acid, neutralized with baking soda/water and then immediately filled and still get surface/flash rust.

I am thinking that it would be nice to take it to a radiator shop and have them boil it out and line it (around $125.00)

But then I got to thinking that the ethanol gas we have to use now might cause problems with the lining.  Anyone have any thoughts on this?  I have a buddy with a plastic ducati tank that is getting eaten up with this new gas and was hoping to avoid a similar situation. 

[BeSeeingYou]

If the tank is solid and not compromised I would not use a liner, period.  Try some CLR on the flash rust.  Neutralize, dry and then use or coat with a light film of oil, tranny fluid, etc.  Works for me.

[Hannibal Smith]

Sometimes the cure is worse than the disease.
There is too much hand wringing when it comes to tank rust IMO.
Unless it is heavy red fuzz, and flaking, then etching will only make the next installment worse.
15 years ago, only worst case scenarios were etched and "lined", nobody just etched and left it at that......at least in the circles I ran with.
Little blotches of light rust won't hurt a thing.
If I run into a tank that rust must be dealt with because it actually is clogging the filters and the like, I go shopping for a new tank.
I hate lined tanks, and fiberglass ones, especially with Ethanol percentages we are running today.

[Bodi]

The tank came from Japan with bare steel inside, and there are thousands still holding gas without help 40 years later.
Lining is a desperate stopgap temporary last resort, for use on a tank that has rusted through and pinholed. The proper fix for that involves welding in good steel.
Ethanol is a problem for many bits in old fuel systems. I have heard that it eats Kreem but POR-15 is OK with it... however I have no direct experience with either (refer to my crotchety opinion on tank coatings above).

[bikebitzofvt]

Keeping the tank full alleviates rusting - no exposure to air means no rusting.  However, some tank designs make it impossible to fill 'em to the brim - the filler neck isn't always the highest point of the tank.

I use POR-15 to line steel tanks that have rusted inside.  The rust is very bad for carburators!  Vibration will pull the rust particulates into suspension in the fuel, they'll be drawn into the carbs, then plugging jets & orifices.  Plugged orifices are bad!  Fuel filters only strain to 75 microns or so, and if a significant amount of rust is present they tend to plug up causing running problems. 

Kreeme's "new" formula says it is ethanol safe, but since I used the POR-15 I will never go back - IMO it makes a great, tough finish and dries nicer than the Kreeme.  One $50.00 can of POR-15 is enough to coat 3 tanks.  I've done 6 different tanks (77 750F, 81 750C, 2 86 xt350, 81 CB450T, 74 550K) in the last year with the stuff and haven't had any problems with it.  As with anything, proper prep work is key!  Oddly, the 550 tank was in the nicest shape when I started of all 6.  Better grade steel, perhaps?  I wouldn't bother with a pin holed tank - that seems like just asking for trouble.

I had to remove an improperly installed Kreeme lining from a XT350 tank last summer.  PO dumped the whole bottle in and let it settle on one side, and didn't remove the scale & rust before hand.  The Kreeme was coming off in chunks.  It took 2 gallons of acetone and about 6 hours of shaking, pouring out, straining and repeating to remove it all.  I then used a 80 / 20 solution of water & hydrochloric acid to remove the rust.  I relined it with POR-15 and have since put 3K miles on the bike running the cheapest 87 octane I can buy without a problem.  It also sat all winter with sta-bil added and carbs (and fuel line) drained.  Fired right up this spring.

My biggest concern with ethanol is what it does to rubber, urethane and poly-urethane fuel line.  Take a couple inches of line and put it in a jar with gasoline.  A few weeks later you can see the particles in the bottom of the jar.  I bought tygon line from K&L that seems to hold up much better, but it's very expensive in comparison.

Just my $0.02...
BikeBitz