Electrolysis works in line of sight. It’s not going to do much inside a water jacket. You may find more success with a product like Evaporust or Metal Rescue.
Coincidentally, Evaporust helped unseize this late 1920’s Evinrude RBM powerhead today. Two days soaking and then a couple heat treatments with penetrating oil is all it took. Admittedly, it wasn’t too rusty inside. Keep in mind this photo is after the Evaporust bath.
Wayne
Upper Canada Chapter
uccaomci.com
