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I’ve been having to start my old ZD 21 with a screwdriver for some time. So I ordered a new starter solenoid and installed it yesterday.
But when I went to connect the battery, the new solenoid immediately
made a “whirring” sound and the battery cable SPARKED.....not allowing me to reconnect the battery cable.
Soooo, I took the new solenoid off and put the old one back on so I could at least start the mower with a screwdriver again. NOPE.same thing happened with the old solenoid now....that Is, upon placing the battery cable back on I got the same “whirring” noise when the cable hit the post.....and sparks.

any help appreciated.

Two things come to mind very quickly. When you install the solenoid you mixed up the wiring. On the solenoid you have either 3 or4 terminals. Let’s say you have 3 terminals, 2 large and one small. On one large terminal you will attach one large cable coming from the battery and one small wire going to the key switch. On the other large terminal you will attach the other large cable which goes to the starter. On the small terminal you will attach the small wire coming from the key switch or safety switch. If you have a 4 terminal solenoid you will hook everything the same, but the second small terminal will have a small wire going to ground.
If you have everything wired correctly, I suspect you have a bad key switch.

You have it wired wrong. Check the cable from batt + to the starter solenoid. It goes on the large terminal farthest away from the starter body. You have the motor engaging but not the solenoid. If it is wired properly the solenoid is shorted but i doubt it with 2 solenoids. With the small wire disconnected from the solenoid does it do the same thing?

Hammermechanicman said:

You have it wired wrong. Check the cable from batt + to the starter solenoid. It goes on the large terminal farthest away from the starter body. You have the motor engaging but not the solenoid. If it is wired properly the solenoid is shorted but i doubt it with 2 solenoids. With the small wire disconnected from the solenoid does it do the same thing?

Click to expand...

Thanks for the reply, Hammer! But, it is wired like you mention. And when the new solenoid made this whirring sound I pulled the new one off and put the old solenoid back on so I could at least jump it with a screwdriver. But no......after putting the old solenoid back on and tried to place the battery cable on.....more sparks and more whirring. The solenoid Wires are on the far terminal just like when I pulled them off. Hmmm

Sorry, I’m now very confused. Can you take a couple of pictures of how you have it wired.

There should be a wire or strap coming out of the motor going to a large lug on the solenoid. The cable from battery + should go to the other large terminal on the solenoid. With nothing comnected to the small terminal the starter motor should not spin. No sparks. If you get the whirring noise which is the starter motor spinning but not engaging the flywheel you have somerhing wrong with the contacts in the solenoid.
When the solenoid engages and extends the starter drive it pushes the contacts closed between the large terminals to energize the motor.

Sorry, I was thinking remote solenoid. If this is basically the starter you are talking about, only two wires should be connected to it. Large battery cable to the top terminal and small wire with spade connector on the side spade. This wire would be coming from the key switch. If you have a third wire it is probably a small wire which will supply current to the key switch and be connected to the same terminal and the battery cable. I know this may not be your exact starter, but shows the terminals. https://www.dbelectrical.com/produc...V5__jBx0BCwmKEAQYAyABEgKV9PD_BwE&gclsrc=aw.ds

Hammermechanicman said:

There should be a wire or strap coming out of the motor going to a large lug on the solenoid. The cable from battery + should go to the other large terminal on the solenoid. With nothing comnected to the small terminal the starter motor should not spin. No sparks. If you get the whirring noise which is the starter motor spinning but not engaging the flywheel you have somerhing wrong with the contacts in the solenoid.
When the solenoid engages and extends the starter drive it pushes the contacts closed between the large terminals to energize the motor.

Click to expand...

Hammer, yes....that strap from the starter is connected to the solenoid terminal that is closest to the starter. That’s where the cable was/is on the old solenoid I replaced. And that’s the same connection I made with the new solenoid. And as mentioned, I out the old solenoid back on.....or tried to. But got the sparks and whirrin. Damn, this is crazy. Maybe it has the virus. Hope not.....I’m too old to be around it?

Here Is pics of my old solenoid back on.

In my opinion you have the starter wired correctly. If you cross the two large terminals, you will get sparks, as you are making a direct connection to spin the starter. The starter will not kick out because you will not energize the solenoid doing this. Have you tried to take a jump wire from the large battery terminal on the solenoid to the small spade terminal? This should energize the solenoid and speed the starter if both the solenoid and starter are good.

Rivet....yes, .to answer your question. Let me start from the beginning.

i purchased the old ZD21 three years ago with 2000+ hrs. Looks rough but runs like a top. I mow my 20 acre yard with it w/o issue for three years . I service It myself regularly. Eveythings good. But after a couple of months of ownership the solenoid/starter begins acting up whereas I could only get the starter to spin by jumping from the lg terminal on the solenoid to the spade terminal. I have started it that way for a couple of years now.......although there was occasion it would indeed crank and start from the switch.

So a month ago I bought a new solenoid and put it on. And that’s where the trouble has begun. So once I put the new solenoid on and found that I couldn’t put my battery cables on w/o sparks and whirring......I put my old solenoid back on so I could at least jump it across to the spade terminal to start it again BUT NO........now the old solenoid does the whirring and sparks too.

Rivet.......thats the way I have started the mower for three years....that is, jumping with a screwdriver. But now, I cant even put the battery cable back on the battery because of the sparks and whirring. I can’t get to the point of jumping it with a screwdriver..

I wish I could.

It looking like you are going to need to replacement the complete starter.

Disassemble the solenoid and check the contact disc. There should be a small spring that pushes it away from the 2 contacts. Either the disc is fused to the contacts or the spring is not there. When the solenoid plunger pulls in it pushes the contact disc against the contacts. If the motor spins when you connect the battery without the solenoid engaging the contact disc is not being pushed away from the contacts.

But why would it be doing the same thing on both my old solenoid and the brand new one?

Remember I’m not there, but have you checked the key switch switch? Switch might be bad locked in the start position.

Don’t mind at all you asking, Rivets. Nope, it’s ok.
At this point, I’ve called my closest Kubota dealer in Monett Mo......some 60 miles away? to come pick it up as I can’t crank it over to start it/ load it. What a bummer. I appreciate yalls help though.

And this actually all began a week or so ago when I felt it time to prepare the old girl for springtime mowing (the mower....not my wife).

And I couldnt get it to start......she wouldn’t hit a lick. (And this is by jumping with a screwdriver) So I changed fuel filters and made sure the fuel pump was working..... new air filter and I even installed new glow plugs. Thats when I decided to go ahead and get a new solenoid.

I know something is shorting out somewhere. Guess I’ll leave it up to the Kubota shop. Again, thx for helping.
stay healthy and safe and God Bless

Sorry I couldn’t help more, but with these systems I wish I was standing next to you. Good Luck and stay healthy, please let us know the final results.

I sure will

KirkKing said:

I’ve been having to start my old ZD 21 with a screwdriver for some time. So I ordered a new starter solenoid and installed it yesterday.
But when I went to connect the battery, the new solenoid immediately
made a “whirring” sound and the battery cable SPARKED.....not allowing me to reconnect the battery cable.
Soooo, I took the new solenoid off and put the old one back on so I could at least start the mower with a screwdriver again. NOPE.same thing happened with the old solenoid now....that Is, upon placing the battery cable back on I got the same “whirring” noise when the cable hit the post.....and sparks.

any help appreciated.

Click to expand...

I had same experience when installed new solenoid. When I put ground cable on battery, sparks flew and got the same whirring noise. Went to old time electric rewind shop and was told what I had done wrong. The starter must be removed to replace the solenoid. The starter has a yoke into which the shaft of the solenoid must fit. This was a chore for a novice, but it worked. I was assured that if the solenoid shaft was fitted into the shaft, I would not get the sparking and whirring, and I did not get this the second time around. I had wired the new solenoid exactly as the old one was wired. I even put the old solenoid back on and got the same sparking and whirring. This was because I had not removed the starter and placed the solenoid shaft correctly into the yoke on the starter. Hope you don't need to do this again, but if you do, remove the starter along with the old solenoid and fit the solenoid shaft into the yoke inside the starter. My ZD 21 is 17 years old and this is the first problem I had. Oh yes, my Kubota dealership charged me $186 for the new solenoid. Wish I had known that John Deere uses the same solenoid and charges $40 for theirs.