# Seized 2 stroke Craftsman



## JnC (Feb 21, 2014)

So a few months ago someone gave me an older craftsman 2 stroke snowblower, model # 536884680. Its a 5hp 21" cut. The thing hadn't been used for over 10 years. 

I brought it home, put some gas in it, some starter fluid and thing fired right up. Put it away to be used later, a week later when I went to use it the machine just wont start up regardless of what I did, took the carb off, serviced it clean and put the blower back in service. 

It had been running like a champ since then, got at least 4 hours of solid workout from it during the huge storm on the 27th and also the one a few days ago. Whilst using it yesterday the engine just stopped working. Leading up to that point it didnt make any funny noises etc, the rpms started going down as if the machine was under heavy load, then it just stalled. 

Tried to start it back up, it did start only to die a few seconds later. 

So I guess I have a seized motor as the pull cord would not budge regardless how much I try, I also tried turning the crank but no luck their either. 

Took the exhaust off and I can see the piston, seems to look bright and shiny without any score marks. I know the only way to find out whats wrong with it is to open the motor but in the meantime I wanted to get some ideas on the matter from people who have been working on 2 stroke motors in the past. 

I am really hoping that their isnt some irreversible damage to the motor and that its only a seized crankshaft bearing as I fell in love with this little machine over the past week


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## detdrbuzzard (Jan 20, 2012)

i use to work part time at a shop that repaired motorcycles, we took in a lot of old two stroke dirt bikes that hadn't been run for years from customers. the first few did as your craftsman did. we decided to try a few with some extra oil mixed in and while they smoked like crazy none of them seized. in your case at least it was a freebee


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## JnC (Feb 21, 2014)

detdrbuzzard said:


> i use to work part time at a shop that repaired motorcycles, we took in a lot of old two stroke dirt bikes that hadn't been run for years from customers. the first few did as your craftsman did. we decided to try a few with some extra oil mixed in and while they smoked like crazy none of them seized. in your case at least it was a freebee



Plan is to see if I can fix the current motor, if not then a replacement motor can be had for around $50, I'd hate to give up on the blower as the little gerbil chews through snow like there is no tomorrow.


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## 43128 (Feb 14, 2014)

tsake some mmo and diesel, make a 50/50 mix and let it soak the piston. put the plug back in, and let it sit overnight and soak, turn the crankshaft with a wrench until it breaks free. run it rich for the rest of its life to prevent future lock ups. works 80% of the time for me on trimmers


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## Shryp (Jan 1, 2011)

I wonder if the rings were sticking and got caught on one of the ports.


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## db9938 (Nov 17, 2013)

Shryp said:


> I wonder if the rings were sticking and got caught on one of the ports.


Could be, or one of the rings let loose and did essentially that. You'll need to take the carb and muffler off their JnC to determine that. 


I would also loosen the spark plug, and see if there is a pressure release. It might have also flooded, and hydro-locked. Especially if everything looks bright and shiny, the cylinder seal may just be that pristine.


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## JnC (Feb 21, 2014)

db9938 said:


> Could be, or one of the rings let loose and did essentially that. You'll need to take the carb and muffler off their JnC to determine that.
> 
> 
> I would also loosen the spark plug, and see if there is a pressure release.* It might have also flooded, and hydro-locked.* Especially if everything looks bright and shiny, the cylinder seal may just be that pristine.



This is my first time venturing into the 2 stroke world, one quick side note here about the events that led up to the seizing point. I had used the blower in the AM for 10 minutes before it stalled on me. Started it up, it worked for a few seconds then stalled again, this happened a couple of times before I realized I was out of fuel, silly me. 


Put in fresh mixed fuel in the tank, go to start the blower and it wouldnt start, usually it started right away with the choke on. I tried yanking the cord for a good minute before giving up and pulling the blower back into the shop for later use. 

After about 5 hours I tried starting it and same thing, it just wouldnt start. Threw in a whole bunch of starting fluid in the carb and tried my luck again, there you go the thing fired up, sputtered for a few seconds before finally getting into rhythm.

From that point on it worked for about 10 minutes before finally seizing. 

Do all these preceding events indicate a flooded motor? 


Motor is off of the chassis and is getting pulled open on Friday.


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## db9938 (Nov 17, 2013)

Hmm, I don't think so. Might try removing the spark plug, the shroud, and see if the flywheel will reverse direction. 

You may also try using the blunt end of a pen to see how close the piston is to TDC. It probably should be just a hair past the end of what the depth of the plug is.


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## JnC (Feb 21, 2014)

As suspected, one of the two bearings on the crankshaft was seized, sort of a relief as the rest of the motor looks great.


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## JnC (Feb 21, 2014)

So I am ready to install the piston back in the cylinder, one issue though, how are the ring gaps suppose to be oriented? The piston does not have locating pins in the grooves, so I have nothing to go by, any help?


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## Shryp (Jan 1, 2011)

I don't know for sure, but I believe you don't want the gaps to be where the ports are.


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## ELaw (Feb 4, 2015)

How many rings does it have?

General idea is the ring gaps want to be away from the ports and away from each other.

So if the cylinder is oriented so the intake/exhaust ports are at 12:00 and 6:00 and you have two rings, put one ring gap at 9:00 and the other at 3:00.

If three rings I'd probably alternate them: first at 9:00, second at 3:00, third at 9:00.


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## JnC (Feb 21, 2014)

Just two rings, piston is flat on the top, thank you so much for the input.


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## db9938 (Nov 17, 2013)

That is some relieving news. I agree with the suggestions on the opposed clocking of the ring gaps, and away from the ports. 

I would also make sure that the bearing race, did not spin in the gear case. After you take the bearing off, just make sure that there is some resistance and it's not marred.


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## scrappy (Dec 7, 2014)

I have never seen a 2-stroke without pins to stop the ring gap from rotating.

Rings will rotate over time and the gap will catch on the port.

Just sayin.


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## JnC (Feb 21, 2014)

The snow gerbil is back together and alive again . It had erratic idle in the past even though I had cleaned the carb real good, apparently there is a pin head sized idle jet in the jet bolt that I missed out. While researching for some pointers I came across this link on how to clean the carb. 

Disassembly, Cleaning and Repair of Tecumseh Carb 640342 on a Sears 143.025071 Engine

the idle jet











a short video, yes it does rattle crazy but nothing is loose on the machine, I like how sears had used locking nuts/bolts everywhere on the machine. 

View My Video


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## db9938 (Nov 17, 2013)

That sounds like an angry snow gerbil.


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