Hot Rods Help Removing pistons from block

This sounds pretty good. If I'm ever faced with this situation again, I'm gonna give it a shot.

 

my local welding shop can get me small dewers of liquid nitrogen for shrinking shafts and such, should have thought about that sooner as its safer than the acid .

 

I've said this before, if they're stuck they're stuck !
The Coke thing, drink the Coke & piss into the cylinders, it'll do more good. I believe that the folks who tout Coke have only used it to derust a screwdriver.
I have tried most of the magic elixirs mentioned here & nothing works, but the dry ice thing might be worth a try.
A big hammer & a 2X4 or drill the pistons with a hole saw & then a big hammer.

 

Am I the only one who has disolved pistons?

 

Well, on purpose anyway! I've vanished some on accident before.....

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400 horse 409 has forged pistons. Not easy to break like cast. My machine shop would just drop it in a vat of something for a couple of days and that's that. Ask a local shop and see how much.

 

you'll probably have to have it bored anyhoo!

 

I like the idea of freezing. Never thought of that. Got any friends with a hot tank? Soak it in the hot tank and get it all nice and warm then some dry ice on the piston don't see why that wouldn't work.

 

We woulda used the hot tank in the old days. I don't have access to one now.
Enough hot caustic will melt those pistons into hot tank sludge if they're aluminum.

I would think forged might take a bit longer, as they're less porous, so less surface area for the bath to contact. I never paid attention to what the pistons were until time to order new ones.

 

nope done it both ways chemically and while running the motor chemically , 5 cent fuse burned up a 15K motor .

 

they still sell caustic at the grocery and hardware store ( lye ) its the same concentration we used in the hot tank . only thing is the hot tanks had a mixer in them that kept the chemicals stirre d up and moving , so they wouldn't saturate and nutralize .. only one place I know around here ( sw chicago ) that has a tank still ( and its only to be used for special customers and to melt pistons they will not use it for that , they will torch out the pistons as its quicker and easier ) all the other shops went to the jet wash and ovens and roto blast , because of the waste disposal issue .

 

One thing that has worked for me a couple of times is to lay the block so one bank of cylinders is vertical, then roll up half a shop rag and put it into each cylinder, along with a mix of 50/50 kerosene and ATF, and light the rags. They turn into large candles that will heat up the pistons and block. Let it cool back down and repeat. After a couple cycles of this it has usually weakened or broken the bond enough to make them come out a lot easier. On those pistons that are at or near top dead center, flip the block over and use the same process from the crankcase side. Learned this from an old pants-pisser that resuscitates old stationary engines, some that have been idle and outside in the elements for 50+ years. He can't break pistons because they're too hard to come by when you're bringing a 1918 McCormick Deering Model M back to life.

 

It's that 3x thermal expansion business that does it. The aluminum heats & cools so much faster that the steel doesn't keep up & it just splits the rusty layer apart. Thousands of psi pressure is developed at the interface.

 

Our hot tank just had some tiny air jets in a pipe on the bottom to keep it stirred up and bubbling 24/7.

 

wonder if it's the sugar content--Mexican coke has a ton of it.

 

Nope. It's the acid.

 

ours has 2 propeller like things that stirred it around , I remember no why he didn't like aluminum in the tank, hydrogen gas formation as it had a gas burner under it to make it boil and the top had a lid over it .

 

Yeah, they're hell on aluminum. One of our rookie guys put an aluminum porthole from some boat in the tank & left it overnight.

In the morning he was asking everyone, "Who took my porthole out of the tank?" LOL

RIP porthole...