6.5hp Tecumseh Problem

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  #1  
Old 11-20-05, 11:22 AM
bizonthunder
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6.5hp Tecumseh Problem

I have a Craftsman 21" lawnmower with 6.5 hp Tecumseh engine I bought new in 2001. I have maintained it well and until last week it ran well. Last week I was going to mulch the leaves in my yard and I started up the mower. It started fine, but as soon as a started to put the engine under a load the engine started making some knocking noises. I pulled it back and the noise went away. I again put it under load and the noise returned. I shut the engine and checked the mower over to make sure everything was tight. Everything seemed to be fine so I started it up again. This time it ran for a short time (about 30 seconds) and then stopped. Now it won't start. I'm thinking I lost a bearing on the push rod, but not sure. I can pull the motor over without any problem when the spark plug has been removed, but with the plug installed the motor with knock and back fire while trying to start it.

I'm wondering if other people have had a similar issue, what was the diagnosis, is it hard to fix, etc? Any info is appreciated.

Thanks,

JJ
 
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  #2  
Old 11-20-05, 06:46 PM
v8driver's Avatar
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if your up to it, pull the head, if its a side valve flat head, its easy. check the valves for proper operation, popping out and in, both of them, and closing fully. doesn't sound like the connecting rod right now. there wasn't anything hit with it? just to be sure.
 
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Old 11-20-05, 07:09 PM
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Was it out of oil? Sounds like it threw a rod to me.
 
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Old 11-20-05, 09:05 PM
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well, if it backfires....maybe not........as for low oil... you said well maintained. i hope checking the oil often was done.
 
  #5  
Old 11-21-05, 12:01 AM
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Ah yes...I see that now. Geez, I need to slow down. I guess I'm reading this stuff so fast I miss important info. I agree, it's not blown if it's backfiring. It could be a valve problem of some sort, or could be a sheared flywheel key, or a loose blade.
 
  #6  
Old 11-21-05, 02:47 AM
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I'll bet the blade was recently sharpened and then reinstalled improperly and/or torqued insufficiently. In which case you need to make absolutely sure the blade is aligned well with the blade adaptor and that the bolt holding it on is torqued well. Furthermore, if this is the case, you will likely have a sheared flywheel key, thereby trowing the ignition off time. Hence the backfire...a new one will need to be installed and the flywheel nut torqued properly.
 
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