Go BottomMassey 245 Coil Problem
 | Todd Wilson
Join Date: Posts: 1 
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2001-04-16 26774
I am posting this for a friend who has a Massey 245 gas tractor. It has started to burn out coils. Its been to the shop and this and that and every 10 hours or so it burns the coil out. The coil has the resistor built into it and the resistor is burning out which in turn burns the coil out. Anyone have any ideas as to why this is happening. Everyone here is out of ideas. Its had a tune up with new plug and wires. All connections and wiring has been checked and cleaned and tightened. Alternator appears to be charging fine. Any help or ideas would be great! Thanks!Todd
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| Larry in MI.
Join Date: Posts: 1
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2001-04-16 26778
Todd there aren't too many things that I can think of that will cause a resistor to burn out. Excessive heat is normally the problem. The excessive heat is normally caused by exceeding the power rating of the resistor. Without going into the P=I2R discussion, my guess would be that the input voltage to the coil is excessive or the load on the output side of the coil is excessive. I would check the alternator output voltage to be certain that it does not exceed the recommended level. Since you say the spark plugs and wires have been replaced, I would venture a guess that the input voltage on the coil is being exceeded or possibly the coil is not mounted in a manner to dissapate the heat properly. Try replacing the voltage regulator if the output is too high. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley 
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2001-04-17 26802
This note is likely to out sort of a jumble, but maybe there'll be an idea too. After verifying the conditions mentioned in Larry's comment, my first reaction would be that it sounds like the dealer is getting the wrong part. Or, there's supposed to be some resistance in the coil primary circuit in addition to the coil itself. A wiring diagram could be checked to see if an external resistor is supposed to be present. A manual also would likely give a spec for resistance or current flow in the primary circuit (breakers closed). The current could be checked with a VOM. Current and resistance readings could be checked both against manual specs and coil manufacturer specs, in case there's been a parts substitution or change in manufacturer since the original equipment.
I can usually come up with some far-fetched ideas. So, here goes: I'd check that everything in the engine compartment is standard. Anything that cuts down on air circulation may cause the coil to run hotter. I have heard of similar conditions that were actually design problems and were cured by adding heat shields. The primary circuit closed breaker current is not the actual operating current flow. The breaker point dwell time and the capacitor affect nominal current. Short dwell time would increase nominal current. However, I can't believe that an ignition system wouldn't be designed so it could remain on indefinitely with the breakers closed since that would be the usual condition when the ignition is on and the engine isn't running. However, a wrong valued capacitor might do something (I did say far-fetched). Arragh, I'm starting to think about spark arrestors, and that's getting too far-fetched, so I'll stop. My best bet is that the primary winding resistance will test different between the original manual specs and the replacement coils, an external resistor is shorted or wired out, or Larry’s checks will prove abnormal.
....
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| Larry in MI.
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2001-04-17 26822
My best guess is that if TomG and I were given a Volt-Ohm-Meter and your tractor that we could fix that sucker!! ....
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