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SimpleMan

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Sure hope someone can shed some experienced light onto a problem my Sovereign is having. Engine is a Kohler OHC 18, with a United Technologies inertia drive starter. Symptoms are...starter will not turn over. Diagnosis I've done so far Checked battery voltage...it was low, so I used a fully charged battery. Same result. Bench tested my Solenoid...it tests perfectly fine. Checked voltage from Solenoid to starter (with key in 'start' position), and the starter still installed in tractor...I get very low voltage at the starter. Did the same check again, but removed the starter (checked empty wire), I then get a full 12 volts. If I put a direct 12 volts to the starter, it still won't spin. Also noticed that my solenoid sounds like a machine gun (ddddd sound) when the starter is installed, With the starter removed it just does a single click when I move the key to the start position. I'm leaning towards the starter being the culprit...but what gets me is that I had the starter bench tested at a local electric motor repair shop, and everything seems to check out fine....other than the 'no spinning part'. Does it sound like I'm on the right path...or should I focus my attention on something else? Thanks all Gord
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Have you tried checking voltage at battery terminals with all wires/solenoids in place and trying to start? Maybe another bad battery? The ddddd sound tells me the solenoid is not getting enough volts to flow enough amps to keep the solenoid engaged. Second thought after bad batery is a bad ground connection. Another test would be to run your 12 volts straight to the starter bypassing the solenoid, and then see if you have 12V at the starter terminal. If you have 12v at the starter with a good cable that can flow lots of amps and a good ground path then the starter sounds like it is bad...
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If you apply 12 volts directly to starter .. Will it engage and tuen motor over? This can be accomplished in two ways. 1. jumper cable from battery post to starter. 2. from one side of solenoid to other. I have found that when putting in solenoid, it is possible for the studs that the battery cables attach to can turn, and causes a bad contact internally.
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Sounds like a short in the armature or the stator. If you disconnected the starter and you see the full battery voltage on the wire, and then less with it connected, you probably have a bad starter.
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Dirty cable connections at battery positive & negative posts. Dirty connections on negative cable at frame connection. Dirty connections on ground cable between frame and engine. Corrosion in positive and negative battery cables. Bad ground connection between solenoid and tractor engine/frame. Bad ground connection between starter and engine. Burnt high resistance contacts in solenoid.
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If you apply 12 volts directly to starter .. Will it engage and tuen motor over? I tried it...starter will not turn. Even on a bench test I cannot get the sarter to spin. UCD. I had thought of the cleaning and checking you mention. Everything checks out fine. Question is, if the high resistance contacts are burnt...would that show on a bench test? Have you tried checking voltage at battery terminals with all wires/solenoids in place and trying to start? Maybe another bad battery? I tried boosting the tractor with my car...same result. Using a meter..showed 12+ volts. I'm leaning more and more towards the starter being the culprit. What gets me is that there were no warning signs of it wanting to quit.
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When you energize solenoid,(disconnected from starter),do you get a good solid click from it??Mine had gotten moisture inside and rust on plunger was hanging it up.After replacing it,I disassembled the old one(carefully drill out the 4 rivets)cleaned the rust out and it works great again.Reassembled w/Pop rivets and now in the"spares"box for another day.^
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On my Kohler OHC 18 the bolts that held the starter to the engine were also the bolts that held the starter together. So, make sure the starter halves are properly assembled otherwise the armature will bind. I taped the halves together when I had my starter off so it would stay aligned while I bolted it to the engine. Depending upon how many hours are on the engine you may an engine problem. The OHC's are famous for failure. See if the engine turns over by hand per Sandhillbill's suggestion. Good luck,
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As Bill said ,can you turn the engine over by hand.I would'nt wish it on anyone but maybe the engine is locked up.Grab the crankshaft up front and see if it will turn.Or you could do the same by turning the pto clutch on the side.
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Starter is shorted internally and draws so much amperage that the solinoid can't stay energized. Even if you "bench test it" it may spin but stop at the short when reinstalled. Dissasemble the starter and replace the brushes.
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I checked to see if I can 'turn the engine by hand'...no problems there. Reinstalled the starter...it cranked the engine over, but alas all was not well. When I tried again the second time I was back to square one...no cranking. Gonna be ordering some brushes for the starter. Is it possible that a faulty ignition switch could cause some of these symptoms?
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I'd take the end cap off the starter and take a look inside before I ordered brushes. I'd bet the armature/commutator is the problem. Ike
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Doughtfull, Seen this a lot on automotive stuff. Brushes get worn and they shourt out causeing tremendous amperage load, but won't entergise the armature. Bump it while it's tried and it most likely will start, untill the bad brush finanny wears out completely. Results are still the same, rebiuld the starter.
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quote:
Originally posted by D-17_Dave
Doughtfull, Seen this a lot on automotive stuff. Brushes get worn and they shourt out causeing tremendous amperage load, but won't entergise the armature. Bump it while it's tried and it most likely will start, untill the bad brush finanny wears out completely. Results are still the same, rebiuld the starter.
That's kinda where I was going......bad brushes arc, short, get hot and destroy commutator surface. If the brushes have worn down to this point no doubt the commutator will need some work. The newer stuff does not seem to have as much to turn down, at least from what I have seen. It's worth a look inside before spending money on brushes that could be spent towards a new starter IMHO. Ike
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The condition I ussaully find is worn brushes and the surface contact from one or two of the brushes fails. Results, dead starter. Or, worn brushes, and the springs start to make contact with the stator or the wires on the brushes short against something internaly. Result, shorted load. I don't normally find the stator needs all that much but maybe polishing a little. I normally scrap the debris out from in between the bars on the stator after I polish it so the fine debris doesn't short the sections together. I have seen destroyed armatures due to exccessive wear or some catostofic failer of something. But rarely is the unit not rebuildable. W/ some starters getting to be better than 75.00 bucks I'm fixing more and more of mine rather than replaceing them. Good luck on whatever you decide to do. A rebuild in most cases last's about as long as a new replacement.
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Ok... things are getting a little wierd now. Pulled the sarter apart. Brushes show very little wear, in fact theres still a lot of brush left. Armature looks 'dark copper color'. Obviously, there is a problem. If I remove the starter from the tractor, and hook up a 12V 10a battery charger to it, it will spin. As soon as I connect it to a 12V battery (fully charged, I tried the one in my tractor, and the one in my car), it will not spin. Then...just to make sure I hooked my battery charger back to it....it spins. I double checked to make sure I was getting 12volts to the starter. Seeing as I'm learning here about 'all things electrical', am I on the right track in thinking that the reason my starter runs on the charger is because it does not have enough amperage to cause the short that makes the starter fail? As a side note, even after removing the starter from the tractor, I noticed a major voltage drop (about 5-6volts) everytime I would turn the ignition switch to 'on' or 'run' I found that I had a short in my ignition switch..I replaced it (thinking that all my troubles would be over) but when trying to start the tractor, the results were the same..no starter action. With the new switch, and the starter in place I notice about a 4-5 volt drop when I turn the key to 'start'. If I remove the starter...voltage stays constant as I turn the key. Conclusions...I'm going to be buying (hopefully a rebuilt, since they're not as much money) starter, since I'm having difficulty in determining the exact cause of the failed starter.
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Wow, now THAT is troubleshooting...of the third kind! Hope that starter solves your problem (I know it will).
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Ok...color me embarresed:I:Ibut I found the main source of my problem. First...it helps if all of ones diagnostics tools are working properly (especially booster cables). I coudn't figure out why my starter would work with a charger, but not with booster cables and a battery. Friend loaned me a pair of decent cables..disconnected the tractor battery, and boosted from my other tractor guess what...sparks at my positve cable. Eureeka...found the cause of my voltage leak. Clean the cables and battery terminals properly, and starting problem is fixed.:D I'm glad that I didn't jump and buy the starter after all. Sometimes it is worth being stubborn. Thanks everyone. Still not worthy to be called a real mechanic...but I'm trying^ Gord
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quote:
Originally posted by UCD
Dirty cable connections at battery positive & negative posts. Dirty connections on negative cable at frame connection. Dirty connections on ground cable between frame and engine. Corrosion in positive and negative battery cables. Bad ground connection between solenoid and tractor engine/frame. Bad ground connection between starter and engine. Burnt high resistance contacts in solenoid.
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Hi, A couple of comments about this starter problem. The most common starter failure we see after the helix on the drive getting gummy and the gear not kicking out, is cracked magnets in the field. These magnets are powdered iron and are molded in a semicircle and glued to the field housing. THESE MAGNETS CANNOT STAND SHOCK. It appears that the most common troubleshooting technique for a starter that doesn't work, is to pound on it with a wrench or something bigger. This cracks the magnets and the little pieces stick to the armature. The clearance between the field magnet and the armature is only a few thousanths of an inch. These little pieces lock the armature so it won't turn or it drags so bad it is worthless. Then when you try to start it the locked armature goes up in smoke or the brush leads get so hot the leads come loose from the brushes. In Briggs starters we have seen a number that the carbon packing that is tamped around the brush leads has come loose and the starter is weak because only 1/2 of the potential torque is available because the other half of the armature gets no juice when one of the brushes is out of the circuit. These are the most common true starter problems we see beyond brushes, turning the commutataor and new bushings. Armatures are tested with a growler which induces an alternating magnet field into the armature. If any of the windings has a shorted turm, a hachsaw blade or thin steel blade will viberate when the armature is rotated and the energy is induced into that portion of the armature. In our starter shop, I would venture that 85% of the solenoids that are replaced are OK. In a starter that has a solenoid actuarted drive. Like a GM car starter or a Kohler Command starter, many Onan starters, and some Briggs Vangard starters, the solenoid has a pull in winding and a hold in winding. The both windings get 12v from the key switch and the pull in winding gets its ground through the fields and armature in the starter. The hold in winding gets it's 12v at the same time and goes to ground. (We see so many car starters come in with a new solenoid that did not fix it and then it comes in to fix the problem.) Since the armature and fields are composed of few turns of very heavy copper strap, they have very low resistance. The hold in winding draws about 10 amps. and the pull in winding is wound of less turns of heavier wire and it may draw from 20 to 30 amps. Since both are in paraallel in the static mode the current draw is from 30 to 40 amps. When the key puts 12v to the selenoid terminal if there is a problem in the starter motor, like the brushes being worn to so the plastic brush holders are riding on the commutator, so the brushes can't make a connection, the pull in winding has no path to ground. The hold in winding which goes directly to ground, does not have the power to pull in the drive by itself. Because the motor is the problem, replacing the solenoid does no good. When it is correct, when the solenoid comes in the contacts connect the battery to the starter motor. This puts 12 volts on both sides of the pull in winding eliminating the current flow through this winding. The hold in winding then holds it engaged. Now lets look at the inertia drive starters. When the 12 volts is applied to the starter from the solenoid the motor spins and because of its mass the armature shaft spins inside the drive gear and "screws" it out to engage the ring gear. At this point it hits the end stop and then turns the engine. It will stay engaged in the flywheel until the engine starts and the ring gear turns faster that the starter and Kicks the gear from overspeed and spins it down ito the starter. These solenoids have to large heavy contacts that have the battery connected to one terminal and the starter to the other. There may be 1 or 2 small terminals If there is one, one end of the coil in the solenoid is connected to the mounting plate. The other end of the coil goes to the little terminal. When the coil is energized, it pulls a plunger with a copper bar to contact the back of the terminals and connect the two together. When the 12v is removed from the little terminal the magnetic field is gone and a spring pulls the bar from the contacts and the starter and battery are no longer connected. If there are two small terminals, the second terminal is usually connected to ground through some safety switches, any of which can keep the solenoid from activating. If the selenoid has 12 v. to the small terminal and it is a 1 small term solenoid and the base is grounded or a 2 small terminal solenoid and the 2 small terminals have 12 volts across them, the Large terminals should be connected together and if there is 12 volts from the battery on one of the big terminals there should be the same voltage on the other big terminal going to the starter. If so the solenoid is working and the problem if most likely elsewhere. As you discovered the most common electrical, not starter, problem is high resistance connections. I will address that later. Al Eden I
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UCD, as you quoted: "Dirty cable connections at battery positive & negative posts." This is exactly why I mentioned the "making sure ones diagnostics tools actually work". At the begining of every thing I had used baking soda water, and wire brushed the terminals on the battery, and the cables. I honestly thought that they were clean. The reason I never revisited it until so much later was that none of my diagnostics seemed not to be pointing in that direction (a bad case of 'tunnel vision' and major inexpierience). After I started using the booster cables that actually work, and saw the sparking I knew what my problem was. Went to the local hardware store, and bought a proper terminal cleaning brush. Properly cleaned everything, and you all know the rest of the story. Life's full of those kind of lessons. Next time I'll know better. As I stated earlier..thanks everybody for the help. I've learned a lot. Gord Al: I agree with CarlH...that explanation can only come from someone who knows what he's doing. Thanks.
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check batt voltage at SIGNAL wire[the small one from ign sw..Its been my experience that with all these damn SAFETY controls,they each lose a bit of voltage and dont give full 12v at signal wire.that wire btw, will operate the solenoid at as low as 10.5 volts,so I would test that first.to fix it if low,you can trace out which safety sw is bad or just put a relay in the starting circiut which solves the prob once and for all,,just did one on a JD,the dude just put a 275 buck starter on it and didn't need one,22 bucks for a relay fixed it..
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