How to restore OMC fuel tank and once restored, how to keep it stored

[Dave Crabtree]

I recently acquired two OMC fuel tanks (with twin lines) that have been used within the last 12 months, so they’re in proven and useable condition.  They were stored until I bought them with 2-3 inches of fuel in them.  External inspection revealed no significant dents or scratches; the paint and decals provide a good patina but a new paint job and new decals might make them pop.  After draining the tanks, internal inspections revealed minimal rust.  There is signs that the gaskets have leaked some and it might be good to replace them.  Is there a good video showing the complete restoration of tanks?  Also, once the tanks have been restored, what are recommendations for the long term storage of a tank that will be used only on rare occasions?  I don’t want them to rust on the inside.  (This has probably been asked a million times but I could not find anything substantial on a search.)

[aquasonic]

Once the tank is clean and ready for storage, Marvel Mystery Oil works well to protect the tank from rust. One ounce of oil per gallon of tank capacity works well. Once added the tank needs to be rolled around to coat all inside surfaces. Two stroke oil is also commonly used.

WD-40 works well for cleaning and preserving the outside. A bath towel over the top will keep it clean in storage. 13 Gallon trash bags are also helpful in keeping the tank clean.

The cause of most interior rust problems is from the tank losing its seal. It can be caused by degraded hose, connector O-rings, upper housing gasket, or bad/missing fiber washer fastener seals on the upper housing. Once the seal is lost, air gets inside, and with air comes moisture.

[Dave Crabtree]

Thanks Aquasonic for the helpful guidance!

[labrador-guy]

Dave here is my 2cents on these pressure tanks.  I have a bunch of them around here and I like them!  I take special care with them.  I keep them inside I keep them out of the dirt.  When you get the black filler housing off you can get in the tank with a vacuum. I use a piece of 3/4″ conduit pipe maybe a foot long and tape it to the vac hose.  That gets the dirt and loose stuff out quickly.  I use enamel paint and put it on with a roller after sanding.  Look the bottom of the tank over good.  Any creases or big dents might cause a leak.  I fixed two tanks so far and when I put pressure in them they leaked from cracks in the bottom!

Remember to unhook the fuel line when hauling your boat down the road.  The shaking will make a bigger pressure than the needle valve in the carb can hold and there will be gas splashed all over.   Hot sun will do the same thing.  Don’t ask why I know this!

JMHO  dale

 

 

 

[outbdnut2]

If you can get ethanol-free gasoline, use it.  Premium or regular.  Ethanol combines with any water that gets in, and also with humidity in the air above the gas.  The resulting ethanol-water mix goes to the bottom of the tank and rusts, as does just having some water droplets in the tank.  That ethanol /water mix also goes through a phase change at low temperatures that is not reversible and not combustible, so that causes additional problems.

The fuel tank sealers at the link below (or other brand equivalent sealers) can help keep your tank from rusting again.  https://www.eastwood.com/por15-fuel-tank-sealer-pint.html

Storage treatments for gasoline, like Sta-Bil, can help keep the gasoline from going bad in ways not related to ethanol, and also keep ethanol from absorbing humidity from the air.  Sta-Bil Marine has twice the amount of ethanol-humidity control in it, but these products do nothing to keep ethanol from absorbing other water in the tank and don’t stop the phase change.  If you have ethanol in the gas, best to store the tank as empty as you can get it.  If no ethanol, have it half full or more.  Gasoline turns bad in ways other than ethanol when there is a lot of air and little gas.

When you restore the tank, be sure to put new O-rings in the fuel line connector that attaches to the motor – there are you-tube videos that show how to do this.  Use Mc Master -Carr #107  O-rings – You won’t find the size you need at a hardware store. McMaster sells a bag of 100 for $2.55 plus shipping.  https://www.mcmaster.com/products/o-rings/o-rings-1~/oil-resistant-buna-n-o-rings-8/

Below is an article about ethanol phase change in gasoline while stored.  Click on it or print it to make it big enough to read.

Dave

 

 

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