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2 questions on engines


TomF

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Hello, everyone! We are working on an 18 hp twin Briggs engine. It belongs to a friend, and he has gone through several batteries. The starter appears to not have enough power to turn over the engine. It cranks it over once.... tries and stalls..... hesitates..... turns over again... stalls. We connected the battery directly to the starter, bypassing all the wiring. Same symptom. This with a brand-new battery. We took the starter motor apart. There were two bent tabs on the rotor where the winding wires connect. These bent tabs were 180 degrees opposite each other. We weren't sure if these were damaged/burnt/melted, or like this from the factory. We're guessing a new starter is in order. Are there any other problems we should consider first? Your guidance is greatly appreciated. Tom Feldpausch and son Peter
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It would be useful to know if the voltage on the battery stayed relatively close to 12 volts when you connected it directly to the starter. If the voltage is lowered significantly, then the starter is probably shorted internally. Another way check is to measure the resistance of the field and armature windings and compare with a good one. Too low a resistance , or zero ohms, might indicate a partial short also. Does the starter rotate freely, from the mechanical point of view? Bearings OK?? Hope this helps.....DaveG
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You might try an auto electric shop, they rebuild starters of all shapes and sizes all the time. They will probably test it while you wait if they're not too busy.
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Having spent time around British cars, also check to make sure that the battery ground connection is solid. As mentioned earlier, check for a voltage drop when the starter is engaged, do it both across the battery terminals and from the starter lead to the chassis. If there is a significant drop at the starter but not the battery, check the grounding. Good luck!
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Has the engine been checked to see if it turns over easily (normal). Could be a binding engine that is taking the starter out. You might pull the spark plugs and turn the engine over to see if it turns freely (remember to account for the resistance of the cam and valves when turning). It is also good if you can get your hands on an ampmeter so you can check the starter current (amp load) when cranking the engine over. Too many cranking amps and you have a bad starter or binding engine. Good luck,

Roy

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Tom, If all the above checks out okay make sure the battery has the proper amp/hour capacity. I tried a 20 amp/hr battery on a kohler starter just sitting on the bench. The starter just sat there and the battery voltage went to zip. Then I used an old 40 amp/hr battery. The starter about jumped out of my hand! Hope this helps. Steve
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