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tk1469's Avatar
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09-07-02, 04:17 PM   #1  
tk1469
Recoil pulls too easy - Sheer Pin ??

I was just given an old Jacobson snowblower with a horizonal shaft 4HP engine. The recoil cord pulls really easy and the mechanism "spins" after pulling it. Somebody told me it could be a sheer pin (?) - any ideas? What is this and is it something I can replace? How would I do it?

 
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09-07-02, 08:45 PM   #2  
mikejmerritt
Hello tk1469, the free wheeling after pulling the starter cord probably has nothing to do with a sheared key. I would look toward a frozen valve and hope that the engine still has an intact rod. Both could be checked simply by pulling the head. If you have a stuck valve some liquid wrench or better PB Blaster shot down the valve stem should free it up with a little effort. If its not a valve make sure the piston is moving when you turn the crank. If both of these check out well it may have a valve that is to tight.....Mike

 
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09-08-02, 02:27 PM   #3  
Another possibility is a rusted up part in the recoil mechanism that's not releasing to engage the spool. Carefully take it apart and see if you don't find something stuck.

 
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09-08-02, 05:36 PM   #4  
I agree with Mike. Pull the head, or use a screwdriver through the plug hole, and make sure your piston is moving. If not, you have a broken connecting rod.


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09-09-02, 03:27 PM   #5  
I could be wrong [hasn't happened this year, but you never know] but I think you guys are missing the point. What he describes sounds more like a recoil mechanism that's stuck in the disengage position than an actual motor problem. If the engine was locked and he gave the starter cord a good yank he should get a few inches of travel and then come to an abrupt halt.

 
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09-09-02, 09:40 PM   #6  
Tow guy....the only reason I'm going with the broken rod or stuck open valve is that the poster said that it keeps spinning after he/she pulls the rope. The clutch dogs in the starting mechanism have to be engaging if the engine continues to spin after pulling on the rope. It doesn't have any compression though, which is letting the engine freewheel easily. That was the key piece of info the poster has given us here. Otherwise, I would go with your reccomendation.


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09-10-02, 04:36 AM   #7  
Right, got that; BUT he says the "mechanism" spins freely. Nowhere does he say that the ENGINE spins freely (or at all).

tk1469 - ?????????

 
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09-10-02, 04:37 AM   #8  
BTW, what's a snowblower used for, LOL.

 
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09-10-02, 07:09 PM   #9  
LOL...I dont see many of those around here either.

The only thing that could continue to spin after the rope is pulled is the engine. The starter spool is connected to the rope and a spring, so it can't keep going. Any clutching drive used will be attatched to either the spool or the flywheel, and cant turn independently of both. The only thing left that could be turning is the engine. It's the only thing that can turn independently of the cranking mechanism.


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09-11-02, 08:35 AM   #10  
Hopefully tk will fill us in and solve the mystery.

 
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