Re: Gimbal Housing Repair???
Pics didn't come through. I don't see in your profile where you're from, but I assume you run in salt water; fresh water where I run, gimbal housing corrosion isn't a real big deal.
Usually the gimbal housing corrodes at the bottom where the U-joint bellows attaches; that's where the water accumulates and does its damage. I have seen them rotted away BAD to the point where the ring the U-joint bellows slides over was rotted well up beyond the groove in the ring. Most notably was last summer when I bought an Ebay A1/G1 gimbal housing from an A-hole in MS who said it was pristine condition only for it to arrive with a fresh coat of paint and the u-joint bellows ring about 1/2 gone - literally. Then the guy yanked my chain about a return/refund and ended up having to file a dispute claim, which I won. Morale of the story: buyer beware, used junk may look nice in pics but pics can be deceiving.
Problem you had with the MIG not sticking is the casting wasn't clean and you have to get aluminum HOT before the wire starts to burn in and grab. I don't think you will be able to fix your problem with a welder, or epoxy. Pop a U-joint bellows when your boat is in the water and you will have a little water leak to contend with. Your problem is a safety issue if you don't realize it.
Obviously, best fix is to put a new gimbal housing on but that requires removing the engine from the boat. I don't even know if you can buy new A1/G1 housings anymore; I think Mercruiser stopped making them some time ago and they only sell the A1/G2 housings for service now (as far as I know). You might be able to get an aftermarket A1/G1 gimbal housing through Sterndrive Engineering but I'm not sure.