Solenoid chattering

[RSKY]

Was going to put wife on mower to mow leaves while I used leaf blower but it won't start. Battery showed charged but I put my starter on it anyway and it still chattered. Shorted across terminals and it turned over for a second but I let the screwdriver slip off. Never could get it to turn over again. I can usually get anything started but have had no luck. Any ideas?

RSKY

 

[TemporaryKubotaOwnerMark]

Solenoids chatter because of low voltage. That can be due to a low battery or a poor ground, or an internal failure.

 

[flyerdan]

Usually when they start doing that it's because the copper contacts have eroded enough that the solenoid can't pull the disc far enough back to make contact. I had that happen on the forklift, took the end cap off the solenoid and the battery contacts were 2 square head copper bolts, turned them so the new part of the head was to the inside, works like new.

 

[Texasmark]

You didn't post a conclusion. If you jumped it once and didn't jump again, that's not the solenoid. As Kabota owner Mark said, that's low voltage.

You turn the key or push the button. A couple hundred milliamperes run down the wire to the small stud(s) and pulls the solenoid rod down making contact between the two ⅜" studs with the copper disc attached to the end of the rod. That action connects the starter across the battery which loads the battery and supply cables/connections.

Once the starter starts sucking on the battery it craters and either the terminal voltage drops or somewhere in the supply cables/connections, you have a corroded terminal dropping excessive voltage....but on this one I'm taking a sulphated up battery that can't supply a good load and maintain terminal voltage.

The voltage available for the solenoid to remain energized has now dropped below 9v or whatever the holding voltage happens to be. The lack of energizing current causes the spring loaded rod to release which releases the contact between the input and output terminals of the solenoid.

This takes the load off the battery and the voltage pops back up.....fingers are still on the start switch so you have adequate voltage back on the solenoid and it energizes again, loads up again, releases again, etc, etc, etc.

Have your battery load tested for 11v at the terminals while delivering 200 amps. If it won't do that get a new one.

Pitted contacts reduce the surface area of the contact surfaces and that reduces the current carrying capacity to the starter. It does just the opposite of what I said above because the starter can't load the battery supply like it should since it can't conduct adequate current through the solenoid.

Pitted contacts continue to erode until the surface area is so small that the copper to copper plate to stud junction welds together and this condition is where you let off the start switch but the starter continues to run. Then it becomes a.......geez, how do I shut this thing off.

 

[RSKY]

Due to having to leave and get granddaughter to spend the night because daughter and her hubby have the flu, I have not had a chance to do anything else to the mower. I suspect the battery is bad and intend to check it out tomorrow afternoon. Will post what I find.

That three and a half year old was talking when we picked her up. Talked all the way the twenty miles to our house. Talked while getting ready for bed. And talked for thirty minutes after she was in bed. Then she woke me up talking this morning.

She is so much like her mother.

RSKY

 

[powerscol]

Give her a hug and give thanks

When you get back to it check all of the ground wires, especially at the relay. Don't just look, take them apart. Then remove and clean battery terminals negative first then with negative off, the positive, Re-install positive first. Be sure all cell on battery have water,. Last check the connections at the starter, Good luck

 

[RSKY]

Took the battery in and it checked okay. So I went to the dealer and got a solenoid. Yep, that was it. First time I've had to replace one since I owned a 1973 Road Runner,....which I sold in 1984.

Thanks for the info.

 

[Texasmark]

Took the battery in and it checked okay. So I went to the dealer and got a solenoid. Yep, that was it. First time I've had to replace one since I owned a 1973 Road Runner,....which I sold in 1984.

Thanks for the info.

Interesting. I'd like to take it apart and investigate the mechanism (that made it fail) since it defies logic.......experience based opinion, nothing more, nothing less.

 

[TemporaryKubotaOwnerMark]

What is there about a failed solenoid that defies logic?

 

[Leejohn]

Go here save you some work.

http://www.dansmc.com/solenoid2.jpg

 

[TemporaryKubotaOwnerMark]

I'm well aware of how a solenoid works. Internal failures causing chattering is nothing new, so I'm not seeing how finding yet another instance of it defies logic.

If you've never run across it before, this might help.

SWITCHES & RELAYS: Cut the Chatter

 

[Texasmark]

What is there about a failed solenoid that defies logic?

What logic? How about a mechanism......sh.. doesn't just happen as is the popular misconception. It's caused and by the symptoms posted, a defective solenoid is not the mechanism. Since it apparently solved the problem then there has to be something peculiar happening inside to make it the root cause and look like a discharged/sulphated battery as the culprit.

Besides I don't know about you as I know nothing about you, but I learn by investigating. I think the NTSB does that too!

 

[TemporaryKubotaOwnerMark]

A solenoid can chatter from internal failures (as I posted earlier in the thread). That's old news. Well-established fact. Unremarkable. Not the most common reason, perhaps, but not exactly Bigfoot rare, either. The mechanism is discussed in the link I posted.


I'm not understanding what you are seeing here that is a mystery. :confused3: There's nothing here to investigate. If someone posted about a head gasket failure due to overheating, I wouldn't investigate that, either. It's old news.

Are you saying you have never heard of solenoid chatter due to internal failure?

 

[Texasmark]

A solenoid can chatter from internal failures (as I posted earlier in the thread). That's old news. Well-established fact. Unremarkable. Not the most common reason, perhaps, but not exactly Bigfoot rare, either. The mechanism is discussed in the link I posted.


I'm not understanding what you are seeing here that is a mystery. :confused3: There's nothing here to investigate. If someone posted about a head gasket failure due to overheating, I wouldn't investigate that, either. It's old news.

Are you saying you have never heard of solenoid chatter due to internal failure?

Yeah. In 60+ years working on electric start engines most of us encounter. With only 2 moving parts there isn't much to mechanically fail...the spring or the plate mounted atop the plunger rod that the solenoid pulls in gets pitted and quits conducting adequate current. So where's the mechanism that conducts long enough to load the battery to the point where it can't exceed the solenoid's coil holding current and it turns loose and then lets go, allowing the voltage pop back up exceeding the pull in voltage of the solenoid coil and the process repeats as fast as the mechanics will allow it.....yet this "internal mechanism" doesn't either weld itself shut keeping the starter energized with the key off, or melting the mechanism and the solenoid just quits responding all together.

My failures were either open solenoids and mostly pitted plates and studs which I opened up, filed off, flipped or spun the plate, pop riveted back together and went on my way.

 

[TemporaryKubotaOwnerMark]

Go read the document I linked. It's a well understood phenomenon. That it has not happened in your experience doesn't mean it's a mystery.

 

[PatrickS2222]

Interesting. I'd like to take it apart and investigate the mechanism (that made it fail) since it defies logic.......experience based opinion, nothing more, nothing less.

Burnt heavy contacts won't INMHO cause it to chatter. You're correct - 95% of cases it's poor battery cable connections or one of the battery's internal cell conductors has fractured. I'd reckon it chattered because of about the only reason that wasn't on your list - the hold-in winding had failed. There's also a (much stronger) pull-in winding, but it's job is completed once the heavy contacts switch power on to the motor - for that reason, the pull-in is earthed to the motor + terminal. It also begins rotating the starter motor armature, which helps meshing the pinion to the flywheel ring gear. This is how the pull-in winding is neutralised - when the heavy current contacts close, 12v is supplied to both ends, leaving only the hold-in winding active because it is earthed to the casing.