Trying to free a stuck engine

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ike61

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Howdy. I aquired a 71 duster that has a stuck 340. I pulled the plugs out and was going to squirt something in the spark plug holes and let it sit over the winter. What is the best stuff to use? Thanks
 
ike61 said:
Howdy. I aquired a 71 duster that has a stuck 340. I pulled the plugs out and was going to squirt something in the spark plug holes and let it sit over the winter. What is the best stuff to use? Thanks
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Get a few cans of Sea Foam
 
WIW '72 340 'CUDA
Post 37
Professor Fate said:
If it's locked, you're probably not going to have much luck on the same day. You may need to soak it and come back in a few days after it's had time to soak in... or even repeated applications over the course of a couple weeks depending how bad it is.
There's lots of "favorite" brews for soaking the cylinders- Kroil/PB Blaster, Marvel Mystery oil, kerosene/ATF mix, etc. The common denominator is that they need time. And when you try, work it back and forth with a breaker bar, gradually increasing the distance you wiggle it. And don't force it too hard CCW, you'll just loosen the crank bolt.
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Sorry for quotes but I'm too lazy to retype it all...:)
 
I loaded up a stuck 360 with Marvel Mystery Oil for a full 24 hours. It worked. Engine ran fine afterwards.
 
The biggest thing is whatever you use, keep the cylinders full. Over time, it will leak past the rings and dry out. Most anything you buy over the counter will be very similar. Marvels is great, SeaFoam......any of them. Just keep a watch on it, keep it full and be patient.
 
After a day, with mild effort, try and turn the crank back and forth with a 1/2 drive breaker bar and socket. You don’t want to put a lot of force on it and break a ring.
 
I've used Marvel but my Uncle swore by Caster oil he said nothing in his career (life long mechanic ) worked better. If you are sucessful put a can of Marvel in with a tank of gas to lubricate the top end .
 
Old trick we used in the junk yard was fill it up with coke a cola over night,it actually worked.
 
I’ve seen pretty good results lately with filling the crank case to the point of overflow and the cylinders with used motor oil (the new 0-whatever blends work best) and a couple of quartS of KW or Motor Medic engine flush and letting it sit. It makes a colossal mess but if it’s water and rust that has it fouled it will break it loose given enough time and patience.
 
I used sea foam, atf and varsol.
1951 flathead 6. After a few days i got against ring gear with a prybar and tweaked it back and forth. Crank wasnt stuck, and it started moving. Connected starter and spun it over a few times. Knocked valves loose and dropped head back on. Cleaned out oil pan and filled it with fresh oil. Got it fired up, and it runs great!
 
Old machinist told me they would use deisel and acetone to free old tractor engines. Same principal... fill cylinders .
I would pull the heads once free if you havent already . Hate to find out its a drooped valve wedged in there .
 
I would pull the oil pan and have a look see to make sure there's nothing obvious going on down there.
 
Once freed up maybe pull the valve covers and watch the valves as you turn it over slowly.
 
Before loading up the cylinders, I would bore scope them to see what the cylinders look like. If there's nothing apparent, then drop the pan and look at the crank. It has to be broken-down anyway, just my point of view.
 
You better run a bore scope into the cylinders first. If one or two had water sitting in them you are wasting your time. Otherwise, I recommend the 50/50 Acetone ATF mixture. I only had one engine unstick from the soaking approach. That was a 273 that had dripped a bunch of stale gas out of the carb over time and had varnished the rings to the cylinders.
 
ike61 said:
Howdy. I aquired a 71 duster that has a stuck 340. I pulled the plugs out and was going to squirt something in the spark plug holes and let it sit over the winter. What is the best stuff to use? Thanks
Click to expand...
Pull the pan.

For all you know... the crank could be broken.
I had a 70 340 4 spd duster once that just wouldn't crank over to do a leak down test on... I put a 1 1/4 on the crank bolt and could turn the crank back in forth a decent amount...but the starter just clunked.
I said fk it, rolled the cherry picker over and yanked it out. Yanked the oil pan and there it was... broke behind the no.1/2 in front of the main.
 
I've used 50 / 50 atf and acetone. Have experimented by adding brake fluid, and another time some diesel fuel to that mix. All seem to do the job, keep fluid in the cylinders. Give it time.
 
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