Broken bolts on Honda 50hp

"I replaced the water impeller

"I replaced the water impeller wheel last year and noticed the bolts were difficult to break loose. There was a previous owner as I bought the boat used, so I am not sure this area had been accessed before. The engine only has 165 hours on it. Recently I was running the motor and took the boat out of the water and noticed the lower houseng was coming loose. On closer look, the 2 bolts near the back of the housing were missing. I proceeded to attempt to remove the remaining 2 bolts and both broke! I thought the first 2 had vibrated loose, but on closer look they too were broken with the shaft of the bolt still in the housing. The question is what to do next. Can a machine shop drill out the bolts and retap the threads or do I buy the piece new? Please help."

"Chris

Try to weld a nut on

"Chris

Try to weld a nut on to the broken bolt. Choose a nut with a hole diameter equal or bigger than the bolt diameter and weld inside the nut. You now have a frozen bolt with a hex head. The trick to free it is to heat the bolt red hot (maybe you already did that while welding. Apply the heat on the bolt, not the aluminium. The bolt will expand from the heat and will break the oxide. Let it cool, and the bolt will shrink somewhat. Let it soak with WD40 for a while, and carefully try to loosen ít (not until its cool, if hot, it is as soft as clay). If you can move it even the slightest bit, you are on the way to succeed. Careful! don’t move it further. Move it back again, and let it rest for a short while, to dissipate the friction heat. Do this small motion once again, and again and again... After several small motions, you will notice that the resistance decreases and the bolt is freeing up. Now it is time to increase the motion (don’t overload the bolt), and soon you are done. Use plenty of wd40, and don’t let it seize because of friction heat.
You got to have a lot of patience for this, and you might have to reweld the nut several times. If it is impossible to move, the threads probably haven’t been heated enough (it takes time for the heat to dissipate down through the bolt stem).
Protect the surrounding surfaces while heating. A piece of sheet metal will protect from the torch, and a wet sponge to prevent too high temperatures.

You can also try drilling it out and use insert threads if necessary.
When you machine stainless steel, you must make sure you have a sharp tool. Never let it go hot. As soon as it goes blue, it will harden, and gets very difficult to drill out. If possible, try to grind off the blue surface, deep enough to get into softer material. Remember to use plenty of coolant. If you use water, the metal will not be warmer than the boilng point (100°C).

Good luck
Robert (from Sweden)"