Heating Metal to Release Filler Plug

[Beltzington]

Hello - Hope this is the best forum for this question.

I have a 3/4" threaded steel plug I can't remove from an aluminum transfer case body. Because of the dissimilar metals not sure if heat would help or hurt loosening the plug. Your advice? Thanks.

 

[RoyJackson]

I'd heat up the aluminum case...however, there are caveats.
Aluminum doesn't change color like steel does as it's heated. Aluminum also conducts heat much better then steel.

A trick I've seen used for heating aluminum is (using an oxy-acetylene rig) sooting up the aluminum by just burning the acetylene (no oxygen initially). Once the area is sooted, turn the oxygen on as you would normally, then burn the soot off. Best done with a rosebud, BTW.
Once the soot is burned off, that's as hot as you want to go. Keep the torch moving too...

Be prepared to turn that plug out as soon as the soot is burned off.

If this is successful for you, don't forget to use anti-seize compound when you put that plug back in...and torque it to spec.

 

[Beltzington]

Thanks Roy for the quick response. I have an oxy-ace setup but the TC is still on the vehicle and I am very concerned with catching the floor-pan insulation, hoses and cables on fire. I will also be lying under the vehicle which complicates this procedure.

Should have been more specific with my question, would heating the aluminum TC with a handheld MAP Torch loosen the threads at all?

 

[RoyJackson]

Can't hurt to try...MAP gas is pretty hot, so be careful!

Another concern is any oil, grease or other contaminant on the surface of the casting...

I'm going to suggest you have a friend standing by with an appropriate fire extingusher and a cell phone when you heat the casting...and do this outside, if possible.

Good luck!

 

[LD1]

A technique that I have had a little better luck with on NPT threads....

Heat the plug itself. Once it is hot (doesnt have to be super hot) take a stick of wax (or candle) and rub all the way around the plug. The wax will wick into the treads, loosen the corrosion, and provide a little lubrication on the way out.

So try that with the wax. But dont try turning right away. Wait until the plug cools a bit. At least cool enough for wax to no longer melt.

 

[RoyJackson]

A technique that I have had a little better luck with on NPT threads....

Heat the plug itself. Once it is hot (doesnt have to be super hot) take a stick of wax (or candle) and rub all the way around the plug. The wax will wick into the treads, loosen the corrosion, and provide a little lubrication on the way out.

So try that with the wax. But dont try turning right away. Wait until the plug cools a bit. At least cool enough for wax to no longer melt.

I'll remember this tip!

 

[LD1]

I'll remember this tip!

I have used it a good bit and never had any issues. But, for whatever reason, it seems to ONLY work on NPT threads. I have tried it on stuck bolts and nuts before but never had any luck:confused2:

 

[RoyJackson]

I have used it a good bit and never had any issues. But, for whatever reason, it seems to ONLY work on NPT threads. I have tried it on stuck bolts and nuts before but never had any luck:confused2:

Probably bcause NPT are tapered...if it doesn't work on standard bolts, it probably won't work on a NPST (straight pipe thread and I may have the acronym wrong).

But even with just standard NPT fittings, still a great tip!

 

[Beltzington]

I'll give the wax a try... if not I'll kick up the heat some. Roger that on the safety observer.

Going to be a few days before I can give this a shot but I will post the results.

Thanks!

 

[LD1]

Do let us know how the wax works out. I know I have used it alot, but cannot recall if I ever have on aluminum??

The place I use most often seems to be on cast engine blocks. The 3 pipe plugs above the cam hole on the rear of the block. It does work like a charm on them:thumbsup:

And if it doesnt work, let us know what does:thumbsup: