Unsticking Stuck Pisons

Sooner or later you'll run across an engine that refuses to turn. And somehow that engine has found its way home with you. Staring at it might work, but heres a few things you can add to the staring in an attempt to get some revolutions out of the old beast. Remeber, regardless of the method you choose, patience is a key ingredient.

These tips where stolen from the members of the Old_Engine echo.

Various solvents have come up in looking at this topic, everyone has their personal favorite, your choice will no doubt depend on what you already have on hand, and what may be an inexpensive purchase.
Some favorites;
-Fuel Oil
-Liquid Wrench
Some of you have probably noticed the similarity in all these components, so we'll leave the choice to you.

"...I filled the cylinder with fuel oil and let'er sit for a week. Then pressurized the cylinder, put a 10' long piece of pipe on the flywheel and bounced on it a bit to break 'er loose." Jim D.

...we used a lot of penetrating oil in the cylinders, put a 36" pipe wrench on the end of the crank. With both of us slowly bouncing up and down on the pipe wrench it finally turned. Got it to where it ran pretty well." John P.

"...Add a zerk fitting to a spark plug shell, then pump the cylinder full of grease and attempt to turn." ?.?
IMPORTANT NOTE:This method is not reccommended as it can crack heads and/or cylinder walls due to the immense pressure. Cast Iron is great when compressed, but does not take kindly to expanding forces of this nature.

"...find a block of wood the size of your cylinder, hollow out the center (to prevent piston collapse) and apply sledge hammer to block of wood." ?.?

"...liberal soaking of penetrating oil." ?.?

Input via the web;

"The best thing we ever found to break a frozen engine loose with was automatic transmission fluid.Since it's hard to tell which of the pistons are stuck, fill each with enough to cover the top of the piston about a quarter to half an inch. Let the engine sit-checking the fluid periodically-keeping the level up for at least a week.This allows the fluid to penetrate.It should'nt take too much pressure to break her free." Dave (solo1160@bellsouth.net)

"...when a bronze housing and an iron bolt won't come apart, apply heat with a torch and melt bees wax into the joints. The bees' wax follows the heat and will penetrate and lubricate the worst siezed assemblies. Try it on that stuck piston. Use plenty of heat (shy of a cutting torch, of course) - - it won't hurt the cast iron. Specially effective on two dissimilar metals, screwed together." DAVEMOWEN@aol.com

And this important word on unsticking pistons with heat;

"As a professional cast iron repairer who fixes many engine blocks of all vintages (with cast iron and LOTS of heat) a word of caution. Cast iron most certainly will crack from excessive heat. CI builds up stress in the metal. At temperatures above 260 degrees, cracking is a distinct possibility (why do you think engines that have been overheated break?) We routinely preheat parts to be fixed to 1100 to 1300 degress F, and one of the reasons we do that is to stress relieve the casting...in other words, we force it to break where it is already stressed.
Don't get the metal red, and easy does it with the heat. Keep at 200F or below, and don't concentrate it in one area. You can buy "temp sticks" from any welding supply house that will let you work within safe ranges." D.J. Baisch (ihorse@srv.net)

"I've heard rumors that iodine works quickly and effectively to free up siezed pistons but you must wash it out right away as it will etch the cast iron . a little dab will do ya" rustfinger@home.com

"I have another suggestion for your readers. My dad passed this on to me after hearing it from an old timer in the engine collecting hobby. He suggested using oil of wintergreen on stuck pistons. I don't know why, but it seems to work. Like any petroleum based oil, you still need patience." Mike (jd_mike@yahoo.com)

Remember to employ all safety precautions when working on any vehicle.
This information is only intended as an overview and may not include all the necessary information, data, or facts neccessary to complete the job.

Return to the OldEngine.org unFAQ page

This Page Created By Alexander M. Bilan (gmguy89@netscape.net)
All Rights Reserved
July 4, 1998
Revision 2.0 February 27, 2000