Solenoid chattering

[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.