Help diagnosing a starter problem with a JD lawn tractor?

8,096 Views | 19 Replies | Last: 15 yr ago by SpicewoodAg
SpicewoodAg
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(I accidently posted this in the Nerdery. I apologize for posting it again).

I have a JD LT155 lawn tractor that will not start. I know:

- battery is good
- cables are good
- solenoid clicks rapidly when I turn the key
- when I remove the cover where the starter engages the flywheel I see that the gear is engaged. I expected the gear to be retracted - but am not certain what is normal.

I don't want to replace a $170+ part without knowing that it is bad. Should the gear be engaged even when the tractor is OFF? Or does it retract when off, and extends to engage when the key is turned to start?

Any help diagnosing this would be appreciated.
wunderbrad01
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The gear should not be engaged, but it is not abnormal for me to find it like that. Have you tried turning the flywheel by hand? It could be that the engine is locked up, or it could be that something got hung between the starter gear and the ring gear on the flywheel and it is just stuck in place.

Also could easily be that your starter or solenoid is being a troublemaker.

[This message has been edited by wunderbrad01 (edited 7/22/2010 2:53p).]
CATAGBQ04
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You mean like it's in contact with the flywheel with the power turned off?

I think you need to visit your local JD dealer...
dave99ag
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This might not be directly related to your problem, I had a similar issue with my JD tractor. A little troubleshooting led me to a bad fuel shutoff solenoid. Cost about $60 at the JD store.
SpicewoodAg
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The engine is not locked up. I can turn the flywheel. I hate to take it to the JD dealer. $$ and hassle factor getting it into the truck.

I gotta admit - I don't understand how the solenoid functions here. I always thought a solenoid forced the starter gear to engage when voltage was applied. On this tractor - the solenoid (according to JD parts diagrams) is a small part, not physically part of the starter motor.

Catag - yes. The starter motor gear is in contact with the flywheel with the key off.

[This message has been edited by SpicewoodAg (edited 7/22/2010 3:40p).]
sts7049
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if the gear isn't retracting, my vote is that it's time for a new starter
CATAGBQ04
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Ditto
el_scorcho
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Starter solenoid opens and closes the circuit to the starter. If the solenoid is sending power to the starter and it does not engage and spin, then it's a starter motor issue. Might whack that sucker and see if the bendix is stuck.
CanyonAg77
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Wow, Deere's online parts catalog lists the starter drive (#2) at $85, the whole starter at $200.



[This message has been edited by CanyonAg77 (edited 7/22/2010 5:24p).]
SpicewoodAg
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Canyon - that's why I want to be sure it's the starter!
sts7049
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wow - well, maybe you can replace certain parts and get away with it, i dunno anything about tractors to be honest.


i would try whacking it with a mallet or something though and see if it unsticks.
TexasRebel
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are you SURE the battery is good?

a clicking solenoid and a gear that wont retract is often a sign of a weak battery.

the gear will retract when the engine starts.
SpicewoodAg
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I used a booster battery to be sure it had enough....

CanyonAg77
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quote:
i dunno anything about tractors to be honest.

What about lawn mowers? That's what it is, not a tractor.


Spice: Wonder if disassembling / cleaning / lubing the bendix would help? And I second the idea of making absolutely sure you're getting 100% power to the starter. Check the voltage at the terminals, or maybe take it off and touch the terminals with a set of jumper cables to see if it works when off.

[This message has been edited by CanyonAg77 (edited 7/22/2010 10:06p).]
Max06
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I have a perfectly running JD LT155 that I'd sell if you want a parts tractor. It is missing hood, seat & deck but otherwise good to go.

I got it as a project but I really need a real tractor for my place.
sts7049
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quote:
What about lawn mowers? That's what it is, not a tractor.


touche. i probably would have phrased that different if i hadn't just come back from happy hour.
CATAGBQ04
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One man's lawn mower is another man's tractor.
SpicewoodAg
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Appreciate the help so far. This weekend I will double check the integrity of the wiring to the starter circuit. Will probably remove the starter and see what I can tell about it. The good news is that it is easy to get to (unlike changing the drive belt - a recent repair).

BTW - just to be clear - it will not crank. The starter motor does not turn. Just the clicking of the solenoid.
wunderbrad01
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If you're this far, you need to test that the solenoid is good. When the key is turned and the solenoid is engaged, verify with a voltmeter that you are getting 12V at the starter.

If you arent getting 12V at the starter, you either have a bad solenoid or the wire between the solenoid and the starter is bad. If you are getting 12V, the starter is the problem. Go ahead and pull the starter and do a little bench testing with a separate battery and some jumper cables to see what happens.

On the more expensive starters like this, it is often times worth the savings if you take the starter to a starter repair facility and have it rebuilt, that is if you know anyone in your area that does starters and you can trust to do it right.
BrazosDog02
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If the starter gear is stuck and not retracting, you should just take it off and haul it to a motor rebuild shop and let them rebuild it. Its cheap and it will fix it. They will put new parts in it and lube it up. I think you have more than one problem here...probably the starter AND solenoid.

A solenoid is like a relay..or it IS a relay...can't remember. They do the same thing. They receive a small voltage from you turning the key and direct a large voltage from the battery to the starter motor. This way, high current does not flow through the ignition switch where it will burn it up. Sounds like your solenoid isnt functioning properly.

[This message has been edited by jed1154 (edited 7/23/2010 4:15p).]
SpicewoodAg
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The winner is.....

TexasRebel.

The battery was good.

The cables LOOKED and felt good.

But I had ~ 12V at the battery + terminal, but only 10.2V at the end of the positive cable. The terminal at the battery was corroded more than could be seen. I built a new cable using some 8 ga. power amp lead with new ring terminals.

Runs very well now.

Thanks for the help.
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