Small Engines (Lawn Mowers, etc.): Tecumseh OHV130

Question
QUESTION: Hello! The quick question is, will damaged magnets on the back of the flywheel prevent the engine from running?  My sister has a lawn tractor with a OHV130 206822A Tecumseh engine.  She said she was mowing the lawn, heard a weird noise and the engine just stopped.  It has a weak spark, the valves are opening and closing as seen with the valve cover removed.  I don't know the compression value.  All I found was a broken magnet under the flywheel.  I removed the broken piece and reassembled just to see if the engine would run again, and it did not.  I primed the engine with fuel directly into the carb, and not even a sputter.  So again, will the engine run with broken magnets on the back of the flywheel?  I have since epoxyed the broken magnet back together but the cold weather has prevented me from testing it.  Thank you!!

ANSWER: Yes, the engine will run with a broken magnet on the back, or inside of the flywheel.  These magnets on the inside are for the charging system.

The magnets on the outside of the flywheel are for the ignition system. If a screwdriver sticks to the outside the magnets then they should be fine.

As far as starting, make sure the flywheel key is not sheared.  You have had access to the key when you removed the flywheel.

If you see spark jump across the spark plug odds are it it fine...just make sure the flywheel is is not sheared.

To see if the engine will start, make sure you have spark.  Remove the air filter and use a small bottle filled with just a little gas and squirt a little gas in the air filter housing...this is basically priming the engine as you know you are introducing fuel.  I use an old diner style ketchup bottle with the long, tapered (pointy) tip.  The engine should as least pop as you prime it.  You should be able to keep the engine running by priming.

Let me know if the engine tries to start when primed.
Eric


---------- FOLLOW-UP ----------

QUESTION: Hi Eric,

Thanks for your advice!  It was warm enough in the Cleveland area for me to go give this tractor a try.  I did install a new flywheel key just for safe measure, per your suggestion.  The tractor still did not start.  A very, very, very weak spark.  Looking in the tractor manual, there are a series of safety switches which will ground out the coil source voltage if for example, someone is not sitting on the seat.  Per the diagram, it makes sense that most of the energy must be going to ground, and I am only seeing 2 vdc at the coil itself.  So I will trace the safety circuit.  The question I have at this time is does that motor have a Low Oil Switch on it somewhere?  That would be something else that would kill the coil source voltage.  There is no LOS shown in the tractor manual, but that manual doesn't show much detail about the engine.   Thank you!!  Dave

Answer
Since you know how to access the flywheel you can access the ignition module.   Remove the top engine cover to access the ignition module and dis-connect the small wire connected to the ignition module.  Re-check for spark.  If you have spark with the small wire dis-connected from the ignition module the module is good and you have a safety switch or wiring problem.

Let me know if you have spark with the small wire dis-connected.

Eric