I have found an aluminum intake with cast plugs screwed into various outlets that have been in there for a long time, is if safe to use a impact wrench to back these plugs out? Thanks

 

Sounds like, a soak with penetrant, maybe a little heat (not a lot) around the opening and an impact gun will likely bang it right outta there. Hit it in reverse, if it doesn’t give way cleanly, add some more oil, retighten, back it off again. Back & forth between reverse/forward and it should come right out. I would not “zip” it out, gradual should ensure you don’t end up with any aluminum threads on the plug. Breakaway is your potential battle, after that should be nuthin.

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^ this..
penetrating oil, little heat on aluminum for expansion and EASY back and forth ( tight/loose) is the answer.

 

I've never had good luck with an air impact on the those plugs, usually it just strips the hex out. Then you find yourself drilling and thread chasing.

 

Thanks, I am concerned about stripping threads.

 

Remember, the key is go slow and EASY. Once you get it to break loose, use penetrating oil and go back and forth as if you were tapping a new thread.

 

In 1970, I bought a 1965 Corvette FI setup for $50. And, as normal in south Texas, the car had been run with plain water--meaning that the fittings were stuck.

I repeatedly heated each with a propane torch and then applied oil. Most came out eventually with hand tools.

One was STUCK.

I took it to the plant where I worked and one of the maintenance guys my age took a small-tipped acetylene torch to it. He heated around the steel plug until well beyond the time I would have stopped for fear of melting the aluminum.

When he stopped heating, he quenched the plug with oil and easily turned it out with a hand tool.

It's still scary when I think about it! But I made that FI assembly a show-piece and it's now worth around $8000.

I'm not recommending this extreme, just explaining that heat on aluminum can do wonders. There is such a difference in expansion rate between steel and aluminum that the bond can't hold forever.

 

^^^ This. Proceed with caution. Heat and oil are your friends. Or just ignore them.