JD 950 Starter Problems

[yooperdave]

My folks have a 1980's JD 950 which they bought new.

During the past few years, when the key is turned to start the engine, only a single click noise is heard and nothing will proceed to try to start the engine.

We thought it sounded just like having a near dead battery, but that does not seem to be it. Our JD dealer who is known for not servicing his customers could not figure it out either.

Yesterday, I tried the key several times and finally got thru to the starter to turn the engine over to fire it right up.

This problem has gotten worse over the years. The tractor could have been running for 6 hours, turned off, and then would not start right after.

Any suggestions or some different tests to try to diagnose?

Thank You

Yooper Dave

 

[BB_TX]

The first thing to do is to clean the battery cable connections. Both at the battery and at the other end of each. This is the typical symptoms of a bad connection. Get a battery brush tool at you local auto parts store. They have a small brush to clean the inside of the clamp and a cup brush to clean the battery posts. If that doesn't solve the problem, take the battery to the parts store and let them test it on their battery tester.

 

[GaryK]

Ditto on the clean connections. Does this tractor have any safety switches that could be disconnected or faulty? If the current is getting to the starter(after cleaning all connections) and still does not start, try jumping the starter, that will tell you if its the solenoid which is a whole lot cheaper to replace than the starter. If you are getting current from the battery to the starter but not the solenoid, the problem may be in the starter switch itself.

 

[ScottAR]

My 1050 does exactly the same thing. Has for years. I even tried another 1050 at an auction and it did it too.

Maybe it'll crank on the first try, maybe the 10th, maybe the 50th. It always starts after it cranks. I took off the starter and carried it down to a local auto electrical guru and he claimed there was nothing wrong with it on the bench. There wasn't either. He jumped a terminal more than a dozen times to prove it.

Somehow, the thing isn't getting enough juice to activate, or it's bypassing itself somehow. I've cleaned every connection I could find. inspected everything I could find, even the little black box behind the dash.
I still suspect the starter, as the replacment looks nothing like mine based on the parts book.

If you all learn anything about this snafu, please post it.

I should add that the 950 and the 1050 share the same engine. The only difference is the 1050 is turbocharged.

 

[755inNY]

Your description of the problem leads to either not getting enough current to the starter (bad connection), a bad solonoid or a starter that is drawing excessive current.

As others have mentioned, remove and clean ALL connections at the battery, starter and the ground to the frame.

You can jumper across the solonoid to see if the starter will turn.

As bushings wear in the starter there is more free play between the armature and the field coil shoes. This can get bad enough to cause excess friction which requires more current to overcome. You could also have a problem with brush wear at the commutator end of the armature.

Jeff

 

[755inNY]

<font color="blue"> took off the starter and carried it down to a local auto electrical guru and he claimed there was nothing wrong with it on the bench. There wasn't either. He jumped a terminal more than a dozen times to prove it.
</font>

ScottAR,

A bad or marginal starter may still "test" OK on the bench. There is no load on the starter. In the tractor when the starter drive gear engages the flywheel, the load on the starter will require more current. If the starter is worn it may not be able to overcome its own internal friction or electrical resistance.

Jeff

 

[BB_TX]

Scott - Just curious. I have never had a problem one with my 950 (except the one time I left my key on and ran the battery down /forums/images/graemlins/blush.gif). The click Yooper Dave speaks of indicates he has enough current to pick up the solenoid (very little current required) but not enough to turn the starter ( a lot of current required). Does yours also do the clicking bit? Or nothing at all?

 

[yooperdave]

The starter was replaced with new at one point, but it did not solve the problem.

How hard is it to bypass the "idiot switches" on this tractor?

I agree that once the starter deceides to engage the engine, it will fire right up.

Yooper Dave

 

[BB_TX]

The one for the PTO would not be hard. There is also one where the H/L lever must me in neutral. That one may be harder. However, since you hear a click of the solenoid, I don't think these switches are your problem. The solenoid may go thru these switches but not the starter motor. Do you have a schematic/wiring diagram of the starting system? I do but it is 30 miles away where my tractor is. If I make it up there tomorrow, I will try to remember to look at the circuit.

 

[ScottAR]

Yes, the solenoid clicks, That's when I know to keep trying. /forums/images/graemlins/blush.gif

I've been mulling over replacing it since a new one wasn't that high when I last checked. (under $100 if I remember)

 

[California]

In the Yanmar forum an owner had the identical problem and determined it was caused by a bad ignition switch. See the 'YM1700 Smoking solenoid' thread over there.

 

[755inNY]

<font color="blue"> Yes, the solenoid clicks, That's when I know to keep trying.

I've been mulling over replacing it since a new one wasn't that high when I last checked </font>

ScottAR,

Have you tried bypassing the solonoid when it is acting up?
Typically there is a small wire that connects to the solonoid from the ignition switch and a large cable from the battery. There will be another connection that goes from the solonoid into the starter, usually it is just a copper strap that comes out of the starter housing.

You can try shorting across the small terminal on the solonoid to the battery cable terminal. A screw driver works pretty good for this. If the solonoid engages and the starter turns over the engine then you may have problems with the circuit feeding the solonoid. If the starter does run, try shorting from the battery cable terminal on the solonoid directly to the terminal that comes from the starter housing (bypassing the solonoid). If the starter turns (drive will not engage engine), then you may have a bad solonoid.

The solonoid has a metal disk inside that, when the magnet in the solonoid is energized, is pull into contact between the battery cable connection and the connection going inside the starter. This disk can get pitted from arcing when the connection is made or broken. The disk tends to rotate a little through the starting sequence and other vibrations. If the disk becomes stuck you can get one spot in the disk that is pitted so bad that will not conduct enough current for the starter. Multiple clicks on the solonoid may result in the starter turning over if the disk rotates a little to a cleaner spot. Of course the problem just gets worse and worse as the poor connection causes more arcing which cause more pitting which causes more arcing.....

If the solonoid elecro-magnet is weak it may be pulling the contact to slowing. This will also cause arcing and pitting.

Make sure you have the tractor in neutral and the brake set before performing the actions above.

Jeff

 

[ScottAR]

If I remember the solenoid is built into the starter housing, so replacing it may require a whole new shebang. When I get the machine home again, I'll look into this further as it's due for some more maintence anyway.

 

[Mark_in_NH]

For the 2 years that I owned my 950, it did the very same thing, I just chalked it up to a sign of age and starter wear.
Other then making sure all possible connections were clean, I never did solve it or really even try to.

 

[BB_TX]

Scott - I looked at my manual over the weekend. I had forgotten that the solenoid not only engages the gear, it is also a relay. It closes a set of high current contacts to supply power to the starter motor. If those contacts are bad, that would also prevent the starter motor from turning. I sent you a PM. If you will send me your e-mail address, I will sent you 4 pages from the manual showing the starter circuit plus some diagnostic information including "If your starter clicks but the motor does not turn". /forums/images/graemlins/grin.gif
Yooper Dave I also sent those to you over the weekend.

 

[yooperdave]

Hi Scott,

Thank you very much for the information.

My sick Aunt died this past weekend, so I was not able to get a good look at the information yet.

I will take a look sometime soon though.

Thanks again

Dave

 

[garry]

My JD 1050 does the same thing. could this be a common JD problem?

 

[jd110]

This is a fairly common problem on 50 series deeres. It is caused by low voltage to the starter solenoid. As these tractors get older, the wiring gets a little corrosion here and there at connections on the key switch, safety switches and other connections. The starter on these seem to be more sensitive to this voltage drop than some others. It is easily fixed by installing a relay in the circuit to energize the solenoid. I have used john deere part # RE44536 to do this repair. It is intended for older deere farm tractors, but it is easily adaptable to 650, 750, 850, 950, and 1050 tractors. The wiring needs a little modification to fit and the instructions for mounting the relay will no apply to compact tractor. I usually mount it on the valve cover. You can also pick up a starter relay at any automotive supply store and fabricate your own wiring.