Do stop/start systems wear out the starter motor? Discussion with an engineer.

[Hersbird]

This is thing is harder to start then a nuclear reactor but very few wear parts. I love the "glow plug". I wonder if a roach would work just as well.
https://youtu.be/01Sr8S9uQMc

[freebeard]

That was a plot point in Flight of the Phoenix.

Brings new meaning to 'hammer down'.

[markweatherill]

Originally Posted by MetroMPG

the oil drain down question

Oh man! Slick 50, Castrol and all the others must one day answer for the received wisdom of the masses that 'most engine wear occurs at startup'.
If so, it's more due to corrosive combustion by-products during warmup and not so much of that there cold-start metal-to-metal contact.

(Oh, and once the engine is warmed up, not every start is a grinding big-end rumbling cold start)

[ThermionicScott]

...90 percent of starter-motor brush wear occurs not during cranking, but during the coast-down after the start has finished.

I did not know that! Thanks for posting, MetroMPG.

[MetroMPG]

That part was news to me as well.

And I don't understand why that's the case, unless it's simply because the motor spends more time spooling down than it does spinning up & cranking.

[MetroMPG]

Makes sense. But how does that cause brush wear? Isn't that more of a stress on bearings/bushings?

[oldtamiyaphile]

If you pull apart a DC motor, you'll find the negative brush is often worn about twice as much as the positive brush, due to the flow of electrons. As such I think most wear occurs while electrons are flowing.

[me and my metro]

They started a new no idling policy at work. As one of the mechanics I was worried about the meter reader trucks. These guys read over 100 meters a day, that is a lot of start/stops each day. This has been going on for about 3 years now and I really haven't seen too many new problems. Luckily we have rotated out the 4.2L Ford v-6 trucks. They were the problem children before the new policy, I think we are down to 1 in my yard and it gets little use.

[gone-ot]

Originally Posted by oldtamiyaphile

If you pull apart a DC motor, you'll find the negative brush is often worn about twice as much as the positive brush, due to the flow of electrons. As such I think most wear occurs while electrons are flowing.

Yep, it's the same process as happened on ignition breaker points, where "pitting" was caused by current-flow actually causing metal-transfer ("pitting") which was offset by adjusting the value of the condenser (capacitor):

"...a MINUS (pit) on the MINUS (neg.terminal) is a MINUS (too little capacitance)..."

[metroschultz]

I've have been working on car & trucks for a living since 1975.
I have seen many different types of starter issues.
I have also noticed that starters on cars with smaller diameter (larger gauge number) primary battery cables seem to die sooner.
The starter in my current DD is 325,000 miles old.
I have buttons on the dash to stop/start the engine.
I use these while driving through town & at lights.
When I put the buttons on the dash, (in summer 2006) I also replaced the OEM battery cables with heavier ones. I used 0gauge (single aught for you old guys) wire & made the cables to my specs.
Negative goes directly to the starter mounting bolt @ the transmission, then a daisy chain ground through the engine bay. This will cause noise in your FM stereo so use aux input or Cd's or a ground isolator module.
Positive to the starter then OEM cable to the alternator.
I've had no issues with my starter and it spins noticeably faster than a car with OEM cables.
High amperage draw kills starters.

Ohms law
Ohms Law Calculator

says that watts = amps x volts,
by reducing the amperage draw on the starter I have effectively increased the voltage to the unit and increased it's life.