Technical Freeing Up Stuck Engine

I've been marinating a stuck Cadillac 390 for 5 months now. Cylinders filled with Acetone and ATF. Pulled distributor, rockers, push rods and timing chain. Cam and rotating assembly good and stuck. Rings must've been fine as the cocktail doesn't run past very fast. Other than patience, what else could help? Thinking about building a device to hold a porta power and gently press the pistons down with the crank out. No rust on the bottom end from what I seen with the pan off.

 

five months...damn...I have no where near that much patience. I would have taken it all apart 5 months ago.

 

You're not going to use those pistons again, anyway. Take a block of wood and a BFH and smack hell out out of them and drive them out. Direction is your choice but probably easier to remove from the bottom.

 

I'm sure that would work.
Personally ,I would loosen all the mains and rods.
I would get it on the floor or a heavy bench, prop it securely where it has clearance to turn.
I would get a decent size ball been and a piece of wood (hardwood preferred).
I would tap one side then the other.
Then I would tap side to side, adjacent pistons.
I really think the shock from the hammer blows will help loosen it rather than a steady push.
Pushing one piston with the port-a power will stress that piston and rod where it will have to push against all seven during a high pressure push.
The hammer blows rely mostly on shock and you can go back and fourth...quick.

 

I'll try those tricks as well. Hoping I can pull the crank easily.

 

I would find a better one. I don't have 5 hours of patience much less 5 months.

 

Loosen the mains and rods, remove as much as you can. Take an air chisel and a slug of steel, I use 3/8th, tape the slug to protect the walls. Start rattling the slug on top of the piston. When you detect some movement, go to another.
I’m guessing rings are froze to the walls. Just need to break things loose.

 

I tried ever mixture of solvent recommended and let it soak for months on end and never had any luck. Even tried heat. I eventually had to torch two rods and beat each piston out piece by piece. I eventually just bought another engine but since I couldn’t help myself and it had started to get personal I did get all of them out without hurting the cylinder walls! Lol


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With the crank in place it will be difficult to actually make any pistons move.
My usual method of freeing stuck pistons is to drill plenty of holes through the tops of the pistons. Drill some 1/2 -5/8 holes as close to what would be the back of the ring land as possible. This reduces the hoop tension and allows the rings to relax somewhat.
As it appears that you have plenty of patience, try to free the wristpin so that the BFH and chunk of 4x4 can actually move the piston. If the the wrist pin is free then the rod can be removed.
If the rings decide that they are happily married to the block it is possible to break a cylinder wall with too much effort applied to the bfh method so the more piston material that is removed the better.

 

We take a plastic 55 gallon drum and fill it half way with a citric acid and water mix like maybe 8:1 or so. Then put the whole motor in. Let it set for a few days. Pull it out, then neutralize the citric with baking soda water mix. You can use another 55 drum and soak it if you like. Never had one not come apart after this. There is no rust left anywhere including in the water jacket.

*** Almost forgot to add this! If you try this be sure and get as much of the ATF and oil out of the engine as you can before putting it in the citric acid mix.**

Oh yeah, this should only be attempted by trained professionals. The description above was performed by trained professionals with years of experience to keep them safe.


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Kinda off the topic of car engines, but years ago I had a stuck Triumph M/C engine. I filled the cyls with penetrating oil and put two heat lamps on it till the penetrating oil started smoking, then let it cool off. I did this for a couple days and sat on the bike in high gear (with a beer in hand) rocking it back and forth. Finally I felt some movement. Then I made the mistake of looking at the spark plug hole when I gave it a big lunge. Got a face full of hot oil when it broke free!!

 

Are your lifters free? I had a big block mopar that had sat in a field for years. I beat the pistons out of it with a sledge hammer hitting on a pipe. Busted pistons all to hell, but they came out. I could see no way to get the lifters out. Ended up junking it... Good luck I hope you get it.

 

hell, if you're really good, like me, you can break all 8 cylinder walls.

 

Friend of mine used a BFH and block of wood on a stuck piston and busted the cyl wall.
the next 312 he bought had the same issue, this time he cut the rod to save the crank and block.
I gouged one out with a torch. No problems.
Drilling holes seem to work well.
good luck

 

Squirrel go it right. that looks pretty bad. just went threw that with a flathead, got 4 out okay, but the 5th one got me.
alot of hammering for nothing.

 

Bathroom bowl cleaner. The kind with acid.

 

You don' t mention taking the heads off. That should be your next move. Clean out any trash and corrosion from the cylinders and see where you are. It might be that only 1 or 2 cylinders are bad, it might be they can all be freed up.
Stuck pistons can be pushed out with hydraulic pressure. Make sure the valves are making a good seal. Make a fitting to screw in the spark plug hole that will take a grease fitting. Fill the cylinder with oil and start pumping your grease gun. This will give you 1000 PSI or more and will shift almost any piston.

 

I've had luck putting them on an engine stand, and turn it so one bank of cylinders is pointed up. stick a half shop rag in any of the cylinders where the piston is down a bit, then add some old oil, diesel fuel, whatever, so you have a molotov cocktail in each of the four cylinders. Let them burn until the fuel is gone, then roll the engine 90 degrees so the other bank is up, and repeat. Do it three or four times letting the block cool between heating sessions. Then pry a bit on the ring gear to see if it'll move.

Do it outside.

 

Have you tried citric acid to dissolve the rust ?

 

I fought a ford flathead for 3 months. Dissembled it as far as I could and left it on the engine stand with cylinders full of my secret trans fluid and acetone mix. Every time I'd walk past it I'd hammer on the pistons with 2 by four and a 4 lb hammer. Once I even set it on fire. After 3 months of frustration I turned it upside down and hammered holes in the pistons....got it apart and sold it to Mike Bishop. He used it in either his F-1 pickup or his Bonneville car.

 

Not sure if the pistons will come out of the bottom due to interference with some of the block webbing. I just knocked a 364 Nailhead apart with a BFH and a long 1" navy bronze drift. If you can't get the crank out, loosen the rod cap of the cylinder you are working on. The porta-power may work, but I would be afraid of pulling the head bolt threads out of the block.

 

I read alot of great ideas and most sound experienced. I haven't done this in forever but we used to use Kerosene and that seemed to work with a piece of hardwood and a BFH. (Big Freaking Hammer)

 

My Dad used to have a two stroke lawnmower, and my brothers and I would gripe about mowing the lawn. One day we got the bright idea of using straight gas in in to kill the mower so we wouldn't have to do the job. Dad would fill it with Marvel Mystery Oil to free it up, then put mixed gas in it and make us finish the lawn. We got away with that trick a couple of times, then he started filling up the gas tank himself instead of letting us do it.

 

You're supposed to change the oil every 3 months, not five. You're 2 month past due. Change the oil and try again in 3 months! But seriously, sounds like scrap at this point.

 

My 50 flattie was frozen from sitting and I pulled the crank and let it sit with some marvel oil in the cylinders. After smacking most of them with a block of wood and a BFH I got all but 2 out without ruining the cylinders. The last 2 I had to make swiss cheese out of by drilling holes though the piston from the top. Once I did that I was able to collapse the pistons in on themselves and they came out. Had it bored out to 3 5/16" and runs pretty good considering where it started!

 

...typical overachiever.......

 

Is it rusted rings or oxidation from the aluminum pistons? You could try some heat.

 

Can you get the crank out of a stuck Cad 390? That would make things a lot easier. I've not worked on a stuck V8 where that was possible.

 

You have to get it to turn so you can get to all the rod bolts.

 

The citric acid really works well . I put a rusty Cad block in one and it cleaned it out perfectly in the water passages. Since you have been soaking it for a while, instead of employing the big hammer theory, I would get an air hammer with a flat planishing type head on the end, and see if it won't jar things loose. Put a thin .060 or so piece of steel on the piston top and then hit it with the air hammer/planisher. If that doesn't loosen it, then try the citric acid. You can get powdered citric acid from Amazon. The crankshaft should be removed if possible so the planishing can be done from both top and bottom. On the bottom side you would need an aluminum rod to stick down past the rod and then planish on it some.