Pulling down a 1960 430 Merc engine. Have three pistons stuck solid from water standing in cylinder. Need help in how to safely remove. I know that some of you "experienced" HAMB'rs know how. I have been soaking these in "rust bust" for 24 hours with no help. Need input.........thanks.
I remember seeing lots of talk on here a long time back about soaking flatty blocks in a barrell filled with some kind of a mollases (sp) and something else. Not much help, sorry. BB
My buddy swears by diesel fuel. He says it takes a few days but that it works. I've never tried this so I can't vouch for it. That's all I got.
How far are you willing to take this? I once spent three weeks soaking a motor only to find that the pistons were actually free the whole time, one of the rod bearings was spun and had seized the connecting rod right to the crank. My advice, take the motor down as far as you can and make sure it is just a stuck piston or three, if it is, I swear by mystery oil. Soak for a day, then track down a block of firewood slightly smaller than the piston. Square up the end of the block and place it on the top side of the piston. Rap the block firmly with a rubber mallet or dead blow hammer. If the piston doesn't show movement in three or four raps soak for another day and try again. You want to be sure the block of wood almost completely covers the top of the piston, this spreads the impact out over the entire surface and reduces the chance of cracking the piston. Good luck.
Well, if the piston rings are rusted to the cylinders, and the pistons are corroded enough that it's all seized up, and the cylinder bores are nice and rusty, it's a good bet you aren't putting the stock pistons back in the holes, because it's going to be overbored. So break the sonsov*****es. Take a nice long, stout drift pin/alignment tool, place it on the dome, just to the right of the pison pin, and knock a big freakin' hole in the dome of the piston. Repeat on the left side of the pin. Repeat until the piston pin is laying on the ground. Surely the piston skirts and face of the piston will have cracked toward the cylinder wall...help them along as needed, and remove the large pieces. Especially if they're cast pistons. In this instance, the piston is expendable, the bore is not. Treat the piston accordingly. -Brad
Any solvent will probably take more than 24 hours. Best thing I've found in 35+ years of messing with rusty **** is KROIL. Soak it, tap it, soak some more, tap it again. If you get tired of waiting just beat the **** out of the piston and plan on replacing it.
Thanks to all for the tips. I'll take oldcarfarts advice first and get some KROIL. Ordered some today. If that don't work, then Brad54's advice is next. I'll just beat the **** out of em till the come out. Sure hope I don't have ta do that cause 430 pistons is hard to come by,,,,but
The wife still uses coke. She's come out into the shop with a can of coke and unstuck atleast one of everything at some time or another.
I have had good success with diesel, it just take some time. I also clean all visible rust with a wire brush or cylinder hone, then soak it for a day or so. I like the coke idea, seems like someone told me about that years ago. James
PB Blaster. That stuff is the cat's ***. Try and hit it from both sides, and let it soak. Otherwise, I've heard Marvel Mystery Oil works well too, and that's suposed to work well on stuck rings also.
Tried Coke vs. Pepsi. I think Coke worked better. We wound up using a lot of beating, though. SAFETY MOMENT: Make sure you use a *long* br*** drift. If too short, one misplaced hammer blow can open up your hand pretty badly on the sharp insides of the bearing saddles. We were harvesting the crank and rods out of a 390 with a badly rusted block. .
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