Catastrophic starter failure. 450C ...CAUTION graphic images

[kilohertz]

So after I figured out how to get the starter out, it took all of 10 minutes (I can't believe I didn't see the hole in the side frame to allow access to the bottom bolt).

Put it on the workbench and dismantled it....It was working last time I ran it, and the brushes looked new and commutator looked good when I removed the end cover to check it....then one day it wouldn't start, and smoke was coming out of the back end. I have never in all of my years of mechanics and rebuilding starters, ever had one that self destructed like this, I have always been able to repair and replace wear items. The commutator bars were ripped out, fine wires shredded...what a mess.

This thing goes straight into the scrap pile and a new starter is on the way. YIKES!

Cheers

[oldmetalmender]

I just did the same on my starter. It was just to replace the jellied rubber grommet for the copper strap. I had no fiber junk. It almost looks like a mouse nest.
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https://www.aspwholesale.com/alternator-parts.html

Looks like you might be better off with a new one.

[LeonardL]

Okay... I'm probably the nearest thing to a dumb ass here but what the heck is all the furry stuff? I have seen starters fry and even explode before and I have never seen one produce what looks like a ground up rat! Holy crap!!

[kilohertz]

Well it was thought that a mouse got in there and made a nest, but I couldn't figure out how that would happen.

I'm guessing it's the fabric that usually insulates the field coils around the case perimeter, but it was all sitting at the bottom, and so much fine wire and the comm bars...I just can't figure how it can go from looking like a re built starter to this basket case in one running of the machine.

[Jim B]

Suppose the drive hung in and took the starter way, way overspeed? That will mess a starter up bad, in a hurry.

[kilohertz]

Suppose the drive hung in and took the starter way, way overspeed? That will mess a starter up bad, in a hurry.

Jim you are indeed a wise man...and now considering the condition of the other end (bendix end) I think you nailed it. I was wondering why the shaft had turned blue right in front of the bendix, and why the bushing in the nose was shot, and I also noticed all the teeth were well mashed and there was no lead angle left on the teeth, just rolled over blunt edges, so the gear must have hung up on the ring gear and went for one helluva joy ride. And to make matters worse, I had run up the engine faster than I usually do as I was testing the hydraulic pump and movement speed. I imagine without doing the math, it could have spun past 20,000 RPM, yikes.

Thank you for that, makes perfect sense.

Ordering a new gear reduced starter tomorrow.

Cheers

[gaspumpsam]

Jim B is right on the money with his suggestion , but maybe also check wiring/ key or starter button for sticking and keeping starter engaged.

[LeonardL]

If you haven't already... I would go ahead and gut the thing to see the rest of the carnage. I agree with Jims summation of it hanging in gear and running with the engine. I've seen that happen before on several starters but they never made it this far. In my experience the drives gave up long before the rest of the starter did. This is pretty incredible to say the least. I've never seen one do this.

[kilohertz]

Jim B is right on the money with his suggestion , but maybe also check wiring/ key or starter button for sticking and keeping starter engaged.

Agreed, the starter button had been sticky with ice but I (usually) am aware of it after each start. It's possible I missed it this time. It's on my list if things to do before the new starter arrives. I also have the tank heater to install, even though it is now mostly above 0 most days. It will make cold starts next winter much easier.

I've pitched it into a snow bank so will have to find it to complete the autopsy.

Cheers

[kilohertz]

The new starter arrived and I installed it today, took about a half hour to complete, the top nut was actually harder getting on than the bottom bolt, was the opposite of removal.

So I ended up buying the 140-914 6601 and it was $100 cheaper than the one that was "supposed" to be the correct one 140-914 6570. Crossed my fingers, flipped on the battery switch and pushed the start button, WOW! That starter spins fast, only needed a sniff of ether and away she went. It was just 0C.

So that's it, starter replaced. We had 6' more snow that slid off the shop roof and completely buried the old starter, so the complete autopsy will have to wait until spring.

Cheers