Starter bendix problem

hello all,
I have a murray ultra with a 16hp briggs. When turning the the key the starter spins good but the gear don't come up and engage with he engine. I can manualy turn the gear and it will engage but when I turn the key the gear just drops back down and the starter spins. Is there a way to replace just the bendix and do yuo think this is my problem?
thanks

 

You can, indeed, replace just the starter gear but you must remove the starter from the engine to do so. Is this a single cylinder 16 or twin? If a twin cylinder, a V-twin or an opposed twin? Have you visually inspected the starter gear and confirmed that it was stripped? I think you need to test, or have tested, your battery and be sure to clean any corrosion from each and every battery cable end related to the start circuit - six total.

 

The ring gear on the flywheel should also be checked for damaged teeth. If needed, it can also be replaced. Briggs stoocks a bendix kit for the starters that contains the gear, spring and drive unit. There will be either a pin or c-clip holding everything togather. Once the retainer is removed, the whole bendix can be removed as a unit. The ring gear is more involved and will require drilling the factory rivets out. The replacement ring is then attached using the supplied bolts and nuts.

 

If the gear goes down when you turn the key after you've "helped" it up by hand, then the battery is connected backwards. If this is the case, you may have more problems to look forward to like a burnt up coil and stator.

 

This sounds logical. The starter turns clockwise so when (if) it engaged with the motor, the motor would spin counterclockwise to start. Is this the way the engine should turn? I have not unhooked anything at all since the last 20 times I've used the mower.
thanks

 

check the battery red to + black to -

 

The battery is hooked up as it has always been. I have not unhooked anything.
Also the teeth on the starter and the flywheel are in great condition. This wouldn't matter anyway since the starter gear isn't making a connection with the flywheel.
Thanks

 

The engine should spin clockwise to start, not counterclockwise. The teeth cannot make contact with the flywheel if the starter is turning the wrong direction. Inertia is what sends the drive gear upward to make contact with the flywheel teeth. If the starter is turning backwards, inertia will send the gear down instead of up.

Just to be sure we're on the right page, you did say that you have manually engaged the gear on the starter with the gear on the flywheel, and it still goes down when you turn the key? This is with the gear firmly engaged with the flywheel?

 

What would make the starter turn the wrong way just out of the blue? Keep in mind nothing has been hooked up or unhooked in well over a year.
This is my problem though. My starter does turn the wrong way.
I was quoted $130 for a new starter from a local service place but I hate to spend that if it might be something more simple.

"Just to be sure we're on the right page, you did say that you have manually engaged the gear on the starter with the gear on the flywheel, and it still goes down when you turn the key? This is with the gear firmly engaged with the flywheel?"

Yes. I engaged the starter gear with the flywheel manually. It stays there until I turn the key then it drops down instantly.
Thanks for all your help so far
Brian

 

Did you look for yourself to be sure the battery isn't connected backwards? (someone messing with it that you weren't aware of maybe?) That's the only thing that would cause it unless someone opened up the starter and reversed the polarity of the permanent case magnets.

 

yes the battery is connected correctly. This mower stays in the garage with only me, my wife and 15month old son having access. My son is too young and my wife can hardly get the garage door open let alone unhook and re-hook a battery..lol This is very puzzling to me though.

 

From what perspective are you refering when you say clockwise and counterclockwise. This should be as viewed from above the engine. Makes more sense than a starter turning backwards...?

 

You say the starter gear spins down after you have raised it into the flywheel and you turn on the switch, then the poles have switched and cause the wrong direction. This usually is the result of a battery being charged with the positive and negative reversed on the battery charger or the battery is hooked up wrong. I had a customer come in with a starter motor that to him was spinning the wrong direction. He was actually pointing the direction of spin to me. When I properly placed the started on a battery with the case grounded and the positive pole jumpered to the post on the starter it spun the direction that it should and the oposite of what he said. After seeing this the customer then went home and changed his battery hook up and the starter cranked the engine. He called back to the shop and said that what he thought was the negative cable was actually the positive but due to the routing under the housings he could not tell which was positive or negative. Everything worked fine for him.

 

Thanks for all your help everyone. After doing some calling around and posting on here, this is what I'm left with. I removed the battery from the mower so the battery is now eliminated from the equation. I ran jumper cables directly to the cables on the mower, red to red, black to black. The black cable on the mower is grounded to the frame and the red goes to the solenoid so I know the colors are correct. Having it hook up "correctly" the starter spins the wrong way. If I hook the red from my truck to the black on the mower and the black from my truck to the red on the mower, the starter turns the right way and the gear engages and the motor turns. The local repair man said in all of his years he has never seen anything like this and can't explain what is going on with it. He said somehow the poles got switched inside the starter although he has never heard of such a thing.
So I guess I'm going to buy a new battery, starter, solenoid, and new wires and make it all like new again and then everything should be fine. The repair man wants to examine the old starter to see what went wrong with it.
AmI missing anything I should replace?
Thanks everyone

 

No...don't do all that. There is a reason for your problem. Do you have a voltmeter? Get one if not (a cheap 20 dollar digital meter will work fine). Then check polarity of the battery, and work from there. The system can't just reverse polarity all by itself. Chances are, none of those parts are actually bad, or if any are, it will be just one.

 

Without the advantage of a disassembled starter motor directly in front of me I'm trying to envision if you switched the terminals on the brush card could you induce reverse polarity? Man, I can't picture it in my minds eye and with reason how this could happen on a DC motor but perhaps it can. Any ideas on this anyone? I could see how this could happen on an AC motor but not a DC motor.

 

easy to do with DC but not so with AC. Many have said you can't reverse direction on an AC motor by switching leads even on a PSC motor. I have seen it on shaded pole motors though, with a rotation direction arrow stamped on it and it clearly rotated the wrong way...for me I simply either replace the fan blade with a different one, but that only delays the inevitable so get it rebuilt instead....

 

ok..so now I've unhooked everything from the starter. The starter is still on the mower but no wires run to it. I hook my negative jumper cable from my truck to the bolt on the starter where the battery lead goes and then just touch the positive to the case of the starter and it spins in the right direction and turns the engine. So I guess I'll just replace the starter. Somehow just sitting a few weeks made the starter switch poles...maybe it got bored or something...lol

 

I've been following this thread with interest and would love to know the hows and whys on this one just for knowledge sake. Sounds like the problem has been isolated though

 

It can't just switch poles. It can't even be purposely switched unless it was disassembled and the case field magnets were flipped over top to bottom, or the armature was rewound incorrectly. Neither of which could happen out of the blue.

I too would like to hear what you come up with as a fix for this. I still think there is a simple explanation.

 

I still don't have anyone who can tell me what happened to this starter. I have another mower so I'm not buying a new starter until I get this figured out.

Brian

 

I emailed a reputable magnet manufacturer about this and here is a copy of the details of such:

Thank you for contacting us. It is possible to reverse the polarity of a magnet by exposing it to a strong magnetic field in the opposite direction. In the case of the backwards starter, I'm more inclined to believe that the starter is wired backwards internally. I don't know how the polarity of the magnets could possibly be reversed with the starter assembled. If you have any other questions, please do not hesitate to ask.

Best Regards,
Kevin Stayer
K&J Magnetics, Inc.
www.kjmagnetics.com



-------- Original Message --------
Subject: Reversal of poles?
From:
To: contactus@kjmagnetics.com
Date: 7/25/2007 7:15 AM

Good day,

I have a perplexing situation and hopefully you can help me out since you are experts in the magnet field. Simply, can a magnet’s poles be reversed, north to south and south to north? If so, how can this be accomplished? Specifically, I am in the outdoor power equipment service business and we have an electric start lawn mower in our shop that has a 12 volt DC starter motor and for some reason the starter motor spins in the opposite direction it is intended to spin. We have eliminated the possibility of a reverse polarity battery by attaching a known, new, correct polarity battery directly to the starter motor, thereby eliminating all starting circuit wiring and we still have a motor that spins in the wrong direction. We have rectified the situation by replacing the starter motor but everyone in the shop would like to know if and how a magnet’s poles can be reversed since obviously this has apparently happened in this case. We have hypothesized that an electrical current applied to the magnetic field in a specific manner can induce pole reversal but aren’t absolutely sure. Can you shed some light on this and, if not, send me in the right direction for an answer?

 

Also note that the "strong magnetic field" required to reverse the polarity of a permanent magnet means VERY strong...much more than any magnetic field it would ecounter under any natural circumstance. If the mower was actually subjected to a magnetic force strong enough to reverse the poles of the permanent magnets, the entire mower would be very magnetized.

Nice inquiry to the magnet company Puey61! I take it you're curious about the situation too, huh? hehe

 

Question, was this starter ever taken apart and put back together.

Had a customer come into the shop last night with a Honda that the starter would not engage the flywheel. Upon examination, the starter was running in reverse. Seems the customer was having a problem with the starter and had taken it apart. Upon reassembly the housing with the magnets was installed out of phase with the brush holder. I noticed that the electrical connection was not in the usual position and the leads were stretching the wire harness. After repositioning the brush holder to the housing, the starter worked properly. Also had to clean up the area of the armature shaft that the bendix rode on to get full engagement to the flywheel.

 

Thanks puey61 for all your help. The starter has never been taken apart. I've owned the mower for 4 years now and the starter has never even been removed. I used the mower a couple weeks before this happened. It did sit outside for 2 nights but I have my yard fenced and security lights. I doubt anyone came in just to change the polarity of my starter..lol Could lightning have hit near it or something? I will not rest until I solve this..It's a mission now!!!
thanks again everyone

 

Lightening would have fried more delicate ignition and stator parts before affecting the starter. The battery was not recharged? Seen farmers do this with an arc welder and get the polarity reversed.

 

no..I eliminated the battery totally. I'm running direct power to the starter.

 

I've been following this thread with great interest and thought I'd throw in my $.02

Just a wild guess here... but what if the starter gear did not fall back down after starting the engine and the engine turned the starter at way more RPMs than it was designed for? Could something have fused?