Helicoil into aluminum - corosion

[IolantheSF]

Put the helicoil in with silicone or 5200, then daub more over everything after you put the bolt in. This will break the circuit that lets the differing metals form a battery.

Alternative: Bore the hole out and rethread it, then use an aluminum bolt of the same alloy. Remember the anti-seize!

[Nicholson58]

What was in the hole? SS bolt? what's the difference - one might ask?

Any number of things suggested above will help. Can you tap over-size and use a larger bolt? There are also other options such as an aluminum Pem-nut. This is a nut placed by a tool & similar to a pop rivet.

[ggray]

You have gotten enough good suggestions, but take comfort in the practice of Volvo, at least some years ago, to build their sterndrives (aluminum) with Helicoils.

[Paul L]

Yes, there was a stainless bolt in there before. It turned out that the material was too corroded to even fit a helicoil. It was valiant try though.