Locked up raptor

hill_racing

hill_racing

New Member
#1
#1
Where do I start with freeing up a raptor? The piston is froze and it has marvel mystery oil sitting in it. I’m not sure who put in the oil because I just got the motor but it obviously hasn’t helped free it up. I haven’t had the side cover off yet but hopefully it’s fine in there. Valves are a little rusty.
 
Triley41395

Triley41395

Well-Known Member
#2
#2
hill_racing said:
Where do I start with freeing up a raptor? The piston is froze and it has marvel mystery oil sitting in it. I’m not sure who put in the oil because I just got the motor but it obviously hasn’t helped free it up. I haven’t had the side cover off yet but hopefully it’s fine in there. Valves are a little rusty.
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You might as well just start tearing it down or take it to someone. If it's frozen, it should be rebuilt anyways. I don't have a lot of experience with these small motors, but I do know that it's stuck because something needs replaced. Just a guess but it's likely seized where the crank and rod connect.
 
hill_racing

hill_racing

New Member
#3
#3
Triley41395 said:
You might as well just start tearing it down or take it to someone. If it's frozen, it should be rebuilt anyways. I don't have a lot of experience with these small motors, but I do know that it's stuck because something needs replaced. Just a guess but it's likely seized where the crank and rod connect.
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Yea I assumed that was nessesary. Should I just try to get the crankshaft out and go from there? I know the valves need out and cleaned up as well.
 
sparkwizard

sparkwizard

#5
#5
Take the side cover off. If you can get a wrench or a socket on the connecting rod bolts, remove them and see if that frees the crank .Assuming the head is off, as long as the crank turns, you can try to flip it upside down and fill the cylinder with oil from the bottom and let it soak that way. You are better off dissolving the rust and not hammering the piston out. I use automatic transmission fluid. Good luck. After you flip it over, you can get the cam out and remove the flywheel.
You want the piston to go UP, away from the crank, not DOWN. that would jam the crank.
 
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sparkwizard

sparkwizard

#8
#8
Head is off I assume. can you use the side of a putty knife, something dull, to scrape the cylinder ABOVE the piston, where the oil has been soaking? No sense trying to move the piston up through that and damage the piston. Scrape it and use a Scotchbrite pad to remove any nasty stuff, then wipe the cylinder dry. Flip it over and fill the cylinder with your choice of fluids. ( NOT EVAPORUST) I use auto trans fluid.
If someone filled the cylinder with MMO from the top, and it is still there, that means the rings are sealed to the cylinder. Top ring is wet, bottom ring is not. By flipping it over and filling the cylinder, you will soak the piston skirt and the lower rings. When the oil soaks through the rings, you should see it in the upper cylinder, dripping into whatever your engine is sitting in.
You CAN use the crankshaft to PUSH the piston up. DO NOT try to pull the piston DOWN. You will mess up the threads in the rod and you will get trapped when the piston is down. Push piston up, remove the crank. Be patient and you might not need to spend too many of your dollars.;)
EDIT: Was the head on it or off, when you received it? Was there a plug in the head?
 
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Harquebus

Harquebus

Well-Known Member
#9
#9
hill_racing said:
...Should I just try to get the crankshaft out and go from there? I know the valves need out and cleaned up as well.
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Take the whole thing apart to assess the condition; it's too easy and basically idiot proof (at least the flathead design is, and that engine in particular*). Take photos if you want and share here. Show us what you're working with.

Follow Sparkwizard's advice.

I am betting and would presume the piston-bore is fine and that the seizure occurred on the crank journal-to-connecting rod, but that is just a haphazard guess. Whoops, Triley already said that. "Great minds" and all that. ;)
 
sparkwizard

sparkwizard

#10
#10
Rings are rusted to the cylinder, crank and rod are fine.
I would bet $20 on that. Rod would not seize to the crank, it would just let go and blow a hole in the block.
While I respect all of your great minds, this time, I don't think we all need to be wrong.:cool:
 
hill_racing

hill_racing

New Member
#11
#11
I have the head off but it was on, and there was a spark plug. Haven't torn apart more than that but I will today. Rings rusted might be a good assumption because there is rust on the valves. I will probably try to get the crank and valve train out and see how it goes from there.
 
sparkwizard

sparkwizard

#15
#15
Was the crankcase full of water like it was playing submarine? What did the oil look like when you drained it?
Black, chocolate milk, or Cream soda?

Either way, remove the cover, flip it and fill it with some kind of oil.;)
 
hill_racing

hill_racing

New Member
#16
#16
sparkwizard said:
Was the crankcase full of water like it was playing submarine? What did the oil look like when you drained it?
Black, chocolate milk, or Cream soda?

Either way, remove the cover, flip it and fill it with some kind of oil.;)
Click to expand...
Haven't drained the oil yet. I opened the fill plug and didn't feel water or oil so that probably isn't good.
 
Harquebus

Harquebus

Well-Known Member
#18
#18
The Marvel Mystery oil is usually used for bigger car engines that are way more of an endeavor to take apart, the owner wants to avoid that, so he soaks the pistons and hopes for the best. This engine is so simple and small that you can disassemble it in short order.

Get to it, man. Take off the sump cover and assess the connecting rod and take off the rod cap, etc. No need for all this suspense. :)
 
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