How to unstick 10 year old engine

Flyboy60

Member
Dec 11, 2004
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How can I get this seize engine rotating without damaging the cylinder walls.
Already use Marvel Mystery Oil but so far NO LUCK.
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Mustang5L5

A little massaging and it went right in
Mod Dude
Feb 18, 2001
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ATF might loosen them up if you have a month or so to let it sick. I think kerosene would do the same.

However that block is going to need machining anyway so you could use more forceful methods as well
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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Take the oil pan off and treat the cylinder wall with trans fluid or kerosene, marvel mystery oil will work too, get enough on the wall to seep down between the pistons and the wall, let it soak. Flip it over and do the top of the pistons. It's messy. Tap the pistons with the wooden end of a hammer, just tap, tap, tap. Do this to both sides of the pistons. It will break loose.
 

CarMichael Angelo

clearly, I’ve got something going on in that hole
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The key here is, not damaging the block, which I want to reuse.
The cylinders are trash. Anytime water has been allowed to lock pistons in place will also do pretty severe damage to the cylinder wall. If they aren’t cracked from freezing, I doubt that a .030/.040 overbore will fix it.
What makes the engine worth worrying about? If this is a common stock block 5.0/302, there are enough of them out there to justify putting a chain on the one you have, and using it to hold your boat in place.
 
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junkyardwarrior

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Jan 10, 2011
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yeah the cylinders and pistons are trashed.

Remove the pan, remove all the rod caps, remove main caps, remove timing set, remove crankshaft, then lubricate the cylinders with ATF or whatever you have, then you're going to have to beat them out manually. I like to use a wooden dowel to beat against the bottom of the pistons, but get several because they will mushroom quickly. With wood you stand less chance of beating up a rod or cylinder badly enough to render it useless. With what I see in the picture, the cylinder wall may not be salvageable anyway. Measure it's bore in a clean cylinder. If larger than 4.000, it's junk. I've been down this road many times and almost all of the time the block is not salvageable because even though the rust is "surface", when boring the cylinders to 4.030, you are only removing .015" from each side and a lot of times there is still water shadows in the soft iron. It may have to go .060". If it's already 4.020 or larger, stop what you are doing, pull the parts that are salvageable, and scrap the block/pistons as they are junk.
 

Flyboy60

Member
Dec 11, 2004
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The cylinders are trash. Anytime water has been allowed to lock pistons in place will also do pretty severe damage to the cylinder wall. If they aren’t cracked from freezing, I doubt that a .030/.040 overbore will fix it.
What makes the engine worth worrying about? If this is a common stock block 5.0/302, there are enough of them out there to justify putting a chain on the one you have, and using it to hold your boat in place.
No freezing where I am at - in the tropics
 

7991LXnSHO

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Sep 1, 2010
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Tractors that are siezed up have a special fluid that comes in old style quart oil cans to free up the pistons and run again. Or at least run until an upcoming rebuild. I cannot remember the name, but NAPA has had it as did O’Reilleys. The cylinders get soaked until it frees up and can turn over.
50/50 acetone and ATF mix is the best penetrating fluid according to a machinist magazine test, and is probably the most affordable in this volume.
 

CarMichael Angelo

clearly, I’ve got something going on in that hole
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I agree the cylinder walls are probably trashed but he asked about getting the pistons unstuck :shrug:
Of all of the sht to have to do...nothing beats soaking, beating, soaking some more, beating, soaking, and finally MAYBE beating out pistons OUT OF A RUSTED, DEAD BLOCK.

Itd be different if the engine was some rare piece. But if this thing is a windsor....( any Windsor)...beating out pistons is just stupid.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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Like I said, it's probably a waste of time, but then it could be a 'numbers matching ' block.
Not like he is resurrecting a 250 ci 6 cylinder so he can put a aussie cross flow head on it. :jester:
 

LILCBRA

I started this morning by knocking out some studs
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Dec 6, 2005
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I echo what everyone else has said, chances are the cylinders are going to be worthless. Why do you want to reuse the block? If it's a numbers matching block to a car that you're looking to do a concours restoration chances are good that you'll have to sleeve a number of, if not all of, the cylinders.