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S

SDE

Well-known Member
I removed the engine from the sled. I have the intake and exhaust manifolds and the heads removed. One piston is at TDC, and so I can not put any fluids in it to soak or to burn it loose. With the other piston at BDC, it will not hold anything either.
This is a 1972 SST340 Chaparral. It had a 1982 plate on it and so it is possible that it has not been running in 30 years.
I put a small block of wood over the high piston and whacked it with a heavier hammer. Some crud came out from above the rings and so I applied some PB Blaster to it.
With the piston at TDC will beating on it with a hammer, get it to loosen up? Will the crank and rod be able to roll over?
Thank you
Steve
 
You could try heating the pistons with a small propane torch. The cylinder walls are probably rusty from sitting all these years. Hal
 
If you can tie the engine down so you can wrap a rope around the flywheel and hang a weight, so the weight will turn the crank. Let it hang a few days.
 
I have removed the nuts that hold the jugs down. I was hoping that if the top piston would go down , that the other piston would lift the jug up. That way I am only trying to get one loose at a time. But I am afraid to pry on the jugs themselves, for fear that I will break something?
Thank you
SDE
 
I have a propane torch. I was not sure if it would provide enough heat to do any good. I will give it a try.
Thank you
SDE
 
After I removed the recoil. I put a pry bar in the slots in the piece that is attached to the flywheel.
It did not feel inclined to move at all. I will see what I can rig up to it when I apply the heat to it.
Thank you
SDE
 
try not to force anything hard--just keep applying your loose juice each day and after a week or two it should penetrate and loosen things up
 
i got a 340tnt skidoo with a good motor if that will fit in it. you can have the whole sled for comming to get it. busted track suspension, rest is usable. in indiana. email is open.
 
i sold and repaired snowmobiles for 20 years and 90% of the time they sat out side and got water in the carb that would collect in the bottom of the crankcase so then the bearings on the crank would rust most had roller bearings on the crank. you should split the crank case and look at it if the bearings are rusted you will have to change them out if you can find them. still have some for JLO & Sacks engines
 
What damage will you do to the Rod Bearings, or
crankshaft, by smacking the piston with a hammer ?
(I've done it, myself, and always worried about
that..I saw no apparent damage with a babbeted
bearing, but a needle bearing connecting rod
could indent or score the crankshaft)
 
It's already broke in a way. If it's been sitting for many, many years, I wouldn't be whacking or prying on anything. Take as much of the engine apart as possible and try to asses the damage. There's also a good chance the engine is toast and will cost a lot to get running again. It's a small engine and is much easier to take apart than say an engine in a tractor.
 
The side on TDC, put the head back on it (with the gasket), tighten and fill through the spark plug hole and let sit. I would try Marvel, ATF or Coke.

bob
 

That would make a great sled for vintage snowmobile racing. They were supposed to have been very competitive at the time.
 

If it is at dead on TDC you might want to rotate the crankshaft while tapping on the piston. Also, placing dry ice on the top of the piston will cause it to shrink away from the cylinder and might just be enough to free up. This of course only works if the piston is aluminum and the cylinder is steel. Take care with the hammer when the piston is cold from CO2 (dry ice).

Good Luck
 
I used a propane torch on both pistons and it still isn't moving. I wondered if something else is stuck. The ring that can be seen on the piston that is down is clean and the both pistons look good. I will play with it some more and then I may split the cases to see if the lower end is the problem.
Thank you
SDE
 
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