70 HP Evinrude exhaust manifold removal

[gdc0581]

I have a 1978 70 HP that I bought as a parts motor. I've removed the PH and completely disassembled it except for the exhaust manifold/water jacket. The head broke off of the first bolt I tried to remove. This is a salt water motor and it looks like the prior owner had never heard of flushing. From the broken off bolt, it is clear that the problem is salt corrosion around the bolt stem. I've tried soaking the block for a week in water with Salt Away flushing solution and this hasn't helped a bit. It is clear that if I try to remove another bolt, it will also break. I've seen some posts that suggest penetrating oil, but I don't think of salt as being oil soluable. I've been thinking of putting the block in a 5 gallon metal bucket and boiling it. Direct heat might be an option for some of the bolts, but I doubt that I could get enough heat to the center bolts. Any ideas from this group would be greatly appreciated.

 

[Dhadley]

Re: 70 HP Evinrude exhaust manifold removal

If it's a parts motor are we concerned that the bolts break? If you just need the plates go ahead and try to remove the bolts. Heat will help. If they break you can still pull the plates off. If they break and you get the plates off it'll be real easy to get heat to them.

 

[gdc0581]

Re: 70 HP Evinrude exhaust manifold removal

True, I don't care about the bolts. I'm trying to save the block. It looks like a light honong would make it servicable and with 6 pistons, I think I can find 3 that will work. My concern is that even if I break the heads off of all of the bolts, I now have a 2 inch thick piece of aluminum held to the block with 18 bolts encased in salt. I don't think removing that would be easy. My real quandary is whether to spend about 800 bucks in boring (the other block), a rebuild kit, water pump, gearcase sealing, etc and have a new engine or to try to cobble together the best parts from 2 engines and get something that will probably work. I figure the minimum repair would involve new rings, gaskets, and a water pump impeller at about 200 bucks. Of course, if I can't save this block, it is a moot point.