My low hour 77 Mercury 700 was spitting water from the relief hole in the exhaust cover, I guess there's a diaphram in there that's torn. Got the gasket kit, began working on it this morning. Several of the bolts are seized, managed to break 1. Felt like it was turning but it wasn't. I sprayed everything down with deep creep several times over the last couple weeks. I'm pretty sure it will be fine with 1 missing bolt, but not half of them.
Any ideas how to proceed? Maybe I should start looking for a different outboard or a different boat.
Got 5 of them out, working on the last one, which broke off flush. 1 of them I was able to grab and twist out with vice grips. For the others I tried a trick I remembered. Heated the remains of the bolt that is sticking out of the aluminum with a propane torch. Dripped candle wax onto it and let it cool to the touch. They backed right out. The last one I have drilled and will insert an easy out and try heating it and doing the same thing. If that doesn't work I'll just drill the the whole thing out.
Another tip I read about was using Alum (Pickling salts). It will disolve iron leaving all non ferrous metals intact. Kind of hard to try this on an engine that is attached to a boat, lol. I thought about trying to build a dam to keep the alum solution in contact with the broken bolt, but didn't want any to somehow drip into a cylnder and cause problems internally.
DO NOT!!! I REPEAT, DO NOT USE AN E-Z OUT! There is NOTHING E-Z about them when regarding steel bolts in an aluminum block! And once they break, you can't do much to get them out as they're hardened and impossible to drill!
Just drill the bugger out and retap it. For future reference, you're on the right track with the heat and patience tactics.
Scott nailed it on EZouts. Retired Machinist, seen my share of broken bolts. They do have a place, as left hand drill, inserts, Heli-coil, etc. But a situation like this, is drill and tap. You can try original size again, go a step up if ya got the meat, or sometimes going to a Metric tap and drill size will help, as different OD's than SAE. Also if its a many bolt plate, and only one broke, try a smaller bolt, then drill and tap the original broke off bolt. Lots of options. But depends on the situation.
Have to say, I HATE corroded in bolts! But patience (red and green wrench too) always gets them out. If its a mobile part, a Machine shop with a EDM machine can burn it out, and thats the only way a broke off hard EZout will come out to. Wish ya luck with this, and don't give up!
In my shop the welder (the guy, not the machine) welds a nub on the broken off bolt with the Heliarc. The heating and cooling usually loosens up the bolt and he can grab the part he welded on with a vice grip. Takes him about 7 minutes. If there is an EZ out broken off in the bolt, it might take and hour or more @ $72 an hour. The EZ out nets us a lot of extra profit. So avoid using the EZ out. Take it to a shop before you try that. It will save you money.
I can second the comments on the EZ out. I had this problem once with some flush bolts in the block and in my opinion the very best way is to take a nut and place it over the broken bolt then use a mig welder to weld the nut to the remaining bolt. The intense heat will help break up the rust seal and you can back that bolt out. Tap and die is a last resort in my opinion because it is complicated and easy to screw up especially is you are working with the engine on the boat. It's one thing to have the block on a level drill press and a whole other ball game drilling it out with a hand tool. Try the welding first - rent one for a day if you don't have one - in the end it's much cheaper and simpler to preserve that thread.
Best method I've found for ones that break off flush, or too short to get a grip-on, is to drill the stainless bolt completely out of the aluminum block.
Then do a Heli-Coil repair. It'll be stronger and more durable than the original. Apply a thin coating of Permatex #3 Aviation-Type gasket dressing to the threads of each bolt, torque to mfr's specs and they will never seize again.
If you try to tap a stainless bolt out of the aluminum block, the stainless is so hard that the chunks will tear out the aluminum, and likely damage the threads in the block beyond repair. Plus you stand a huge chance of the tap breaking, and then you're worse off than before.
Much easier to not fight it, once you've completely drilled out the stainless bolt it'll take less than 5 minutes to do a Heli-Coil. The kits aren't inexpensive, but they're so handy and will pay for themselves over time.
Couple more good ideas there. And if is a steel bolt, the "weld a nut on" works too. But like Ed said, if its Stainless, and you have the meat to drill a the larger Helicoil drill tap size..(Helicoils use a different size tap drill), as I think we are talking 1/4-20 here, right? That a "G" drill, for the Helicoil tap. Its a .260 letter drill. I would have to go out in the shop for accurate, as coming off the top my head here. What we are talking here, forgot to go back and look..Exhaust/water jacket plate? Go get a Heliciol kit for the bolt size. End of problem....that would be the way to go. Also make sure you get the center of the broke bolt, as you want all the old bolt threads drilled out.
And Ed, you sure nailed it here (and imagine you and Thom have seen this more than once).....YOU ARE SO CORRECT HERE. Seen it too!
"If you try to tap a stainless bolt out of the aluminum block, the stainless is so hard that the chunks will tear out the aluminum, and likely damage the threads in the block beyond repair. Plus you stand a huge chance of the tap breaking, and then you're worse off than before."
I agree with all the comments but it is a better idea to pull the powerhead and drill out the broken bolts on a drill press, with GOOD bits, not the hardware store kind. Better still take it to a trusted machinest to have them removed, money well spent.
I replied to this a while ago but somehow it disappeared. Anyways I got them all fixed. Drilled and tapped the last 1 or 2 that need it. Chased all the other holes to clean them up.
I ordered the powerhead gasket set and the one gasket that was actually bad causing my leak is not included. Not sure what to do at this point. Under the water jacket cover on the port side is a spring loaded diaphragm. It's near the thermostat. The diaphram was torn causing the leak that started this whole mess. Checked with the local places, everyone looks at me like I'm working on the space shuttle or something. I have been unable to find reference to it online. Maybe I have a rare one of a kind factory prototype with this part in it, who knows. Anyone know what it's called or where to get it? Luckily I live in Southern California so there will still be scattered opportunities to take it out.
Electro Arc Disintegrators are great if you can take the part or the engine to a machine shop. It is expensive - but the original threads of the casting are retained and undamaged. It is an amazing process.
PS I had to have this done to remove an EZ out once. I went home & tossed my other EZ outs in the trash.