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From: Hank Dozier
Date: April 19, 2002
First of all, in most places, due to environmental rules, they do not hot tank anymore. Now thes parts get cooked in an oven at about 700 F and then the residual is shot-peened off. This presents some different issues, though, compared to hot-tanking, so lets answer both. Hot tanking is a hot liquid, generally caustic, solution, so ALL aluminum, pot metal, and other light alloy parts need to be removed. The solution also is detrimental to rubber parts, so whewn you do cylinder heads, remove all valves and seals. For blocks, knock out the cam bearings (it will eat them anyway), but you want the solution to get forced through the passages to clear out the oil sludge. Ditto for the welch/core plugs. You cannot do aluminum parts in hot tanks. For the oven process, you have to remove all the cam plugs, and for cylinder heads, be advised that you disassemble them to protect the springs at that temperature, as well as to cook off the crud in the spring pockets. Blocks get disassembled the same way, same reasons. Heads will generally need a valve job, but as the crud means the head is old, you want one anyway. You can oven cook aluminum blocks and head, timing covers, etc. They afterwards use bead on aluminum, not steel shot for the final cleanoff. Hope this helps.