MTFCA Forum

I have a very nice original 1914 gas cap that is cemented by rust into an un-salvageable tank, so a ring of tank metal around the cap was torched out of it. The heat didn't affect the rust cement any; the cap is still firmly in place. Can anyone recommend any one type of snake oil penetrant that won't hurt the aluminum? I don't want to experiment on this one; it's too nice. Flip side: any that will damage aluminum and should be avoided?

Aerokroil works good and I have never seen it damage aluminum.

Kroil
http://www.kanolabs.com/

I’ve never found anything that works well on aluminum to steel.

Is it really aluminium, or pot metal. If pot metal I would advise grinding the steel back all round so that you have a ring of steel around the cap. The heat generated may loosen things a bit. If not , continue to grind in one spot until the threads on the cap are just exposed. That will allow you to see where a Dremel cut-off wheel can be used to cut along the remaining threads until you can break the steel ring free. There is every possibility thet the cap threads will still need to be filed/dressed before it will fit back into a tank fitting.

Hope this helps.
Allan from down under.

Thanks all. The cap is aluminum and not potmetal. I have a gallon can of Kroil so I will go ahead and try that. I was going to anyway but I thought I'd better check with those who have more experience than I in this area. Will let everyone know how it comes out. Literally.

I have had great success with a heated ultrasonic cleaning tank using Evapo-rust. It dissolves the rust (Iron oxide) leaving steel, Iron and aluminum unharmed. I used to use reverse electrolysis (and still do for large Items like engine blocks but this Is the best way to remove rust on smaller Items like carburetors.