Steel plug frozen in Aluminum tank

[Fred Mc]

I have an extra aluminum tank off a semi that I want to use as an aux tank and it has a steel plug siezed in the tank. The area it is screwed into appears to be approx. 1/2-3/4" thick and I'm wondering how to free it. Ive tried brute force which isn't working. I know with steel to steel you can heat the area and melt wax onto the threads which will free it up but not sure about aluminum.
Any ideas?

Regards

Fred

[Lin]

I read somewhere that the best penetrating oil was a 50/50 mixture of transmission fluid and acetone.  Since the expansion rates of steel and aluminum are different, heat might do something too.

[eagle19952]

The hard part is holding the tank still...

[Iceni John]

Back when I worked on bicycles, we found bleach to be effective at breaking the galvanic corrosion between steel frame tubes and aluminum seatposts or between steel forks and aluminum handlebar stems, something that happened all too often on triathletes' bikes  -  they sweat a lot!   I don't know how or why it works, but it usually did.   When steel pedal spindles' threads were corroded into aluminum cranks, that's the only time I used heat, and then only sparingly.   Otherwise, several applications of penetrating oil over a week or two would usually work, with moderate heat before each reapplication.   Aluminum's coefficient of expansion is about twice that of steel.

Good luck!
John

[RJ]

Fred -

Might try Kroil.  Best penetrating fluid I've ever worked with.

Available on Amazon, eBay, etc. or direct from manufacturer www.kanolabs.com

FWIW & HTH. . .

[Oonrahnjay]

    What's the diameter of the plug?  Heat usually works best with a larger plug.  Posters above have given you good advice -- usually you find that work on it and work on it and it just won't move, then all of a sudden (particularly when the penetrating fluid you're using has worked in) it will come out easily.   Take it slow and carefully, it will work.

[Debo]

I'm sure you thought of this, but since you didn't say what the tank was used for on the semi, use all appropriate caution when heating if it used to be a fuel tank.

[scanzel]

How big in diameter is the plug. You could try just drilling it out, drill a hole inn the center and keep enlarging it until you get close to the threads and then give it a few side taps and it will seperate from the threads. This is what I did a few times.

[wal1809]

An old trick we use for chokes stuck in shotgun barrels will work.  Use a penetrating oil of your choosing.  Heat the area with a heat gun or even a hair dryer.  Get it good and hot, then put the oil to it.  Keep heating and treating with oil.  the expansion and retraction will get the oil to its destiny in time.  I hunt the Texas coast and more often than not, shotgun barrels get stuck from the salty atmosphere, if not out right sticking your barrel in the salt water. 

The best thing we found is a baby food jar full of penetrating oil and a one of those coffee cup warmers for you desk, hot plate thingy.  We set the jar of oil on the hotplate and set it on the floor.  Put the shotgun barrel in the oil and stand the shotgun in the corner.  Leave it run for the night.  Never have I not been able to get one first try after that.  So if you can figure a way to submerge the plug and apply heat for a lengthy amount of time (24 hours), that plug will bust loose.

[bevans6]

aluminium corrodes preferentially to steel, so there is likely a solid oxidization layer between the plug and the tank bung.  I would heat the plug to dark red fairly quickly, and take it out with an impact gun.  You may find ruined threads from the oxidization tearing.  If you need the hole you can retap, if you don't need the hole you can weld it up.  Dark red steel is just below the melting point of aluminium, the heat will transfer slowly through the oxidization layer, and the aluminium hole will expand roughly twice as much as the steel, so the hole will get bigger than the plug.

Brian

[Jim Eh.]

If it is just a port you need have a tank repair facility install a new one where you want. Most likely the threads are going to tear out when you do get that sucker turning anyway or at least be corroded away to the point of being unusable.

[Lin]

I am sure that you will be able to get it out, but another approach could be just to leave it in and drill, tap and plug a new hole through the old plug.

[Fred Mc]

Success

I wound up heating the plug with a propane torch and melted some wax onto the plug and then used a vice grip to turn it out. It came out very easy probably due to a combination of the heating of the aluminum AND the wax. Worked like a charm.
And on the subject of removing rusted nuts I'm sure most people know that if you heat the nut red hot it will then come off very easily. Very good for situations like rusted nuts holding the exhaust pipe flange onto the exhaust manifold.(i.e. on a BB chevy) If you twist off the stud trying to get the nut off it is a real pain.

[Oonrahnjay]

Success

I wound up heating the plug with a propane torch and melted some wax onto the plug and then used a vice grip to turn it out. It came out very easy probably due to a combination of the heating of the aluminum AND the wax. Worked like a charm.
And on the subject of removing rusted nuts I'm sure most people know that if you heat the nut red hot it will then come off very easily. Very good for situations like rusted nuts holding the exhaust pipe flange onto the exhaust manifold.(i.e. on a BB chevy) If you twist off the stud trying to get the nut off it is a real pain.

    The old smoke wrench works again.  Glad to hear you got it.  What shape are the threads in?

[Fred Mc]

Threads are perfect.