Car wouldn't start, would sort of crank, but not well. Went down and looked at the starter, found this:



I've never seen a starter crack like this before. Have any of you? What on earth causes this? The car ran just fine, then one day didn't start. I didn't run over anything or have something fly up under the car. It seems very odd to me.

 

i've seen that happen a few times. it's usually do to a cracked outside started bolt hole in the block. check your block out very carefully. look at your starter bolts too, sometimes people over tighten them, bottoming out the shoulder or knurl, cracking the hole. are you running a front starter support bracket? if not, you should.
http://www.summitracing.com/parts/nal-354353

 

some pics of said crack;
http://www.carcraft.com/techarticles.../photo_01.html

 

Could also need to be shimmed or possibly caused by a damaged flywheel. I've also read that it can be a timing issue.

 

Moisture in the distributor, and a resulting crossfire during start, can cause that.
A cheap Chandler distributor cap on the L31 in my pickup did it.

 

check that the flywheel isnt bent or damaged. my car was eating starters just like that ended up the teeth were chewed up from something that made its way into the inspection cover

 

I had a starter in an S10 truck crack exactly like that. It was the timing to far advanced while cranking. It was computer controlled timing and there was actually a TSB through GM, and I have to have the ECM reprogrammed. It started fine after that.
Pretty much the engine will try to fire to soon and it will kick back against the starter.
Don't know if your timing is off, but something to check.

 

Looks like kickback. I had the same problem on my carbed 355.

To OP: does the car have any mods or is it stock?

 

Looks like....

Rebuilt starter that had some abuse in its history.

Not much sense in over-analyzing it. Paralysis by analysis, as we say when dealing with pathologically risk-averse types in the business world.

Replace it. Turn that one in as the core. Move on. Don't waste any further mental effort on it, not worth it.

 

Wow, thanks for all the great replies! Crawled under the car and did some inspection today:

1. Flywheel checks out OK.

2. Engine block is not cracked (phew!)

3. I'm pretty sure the shims aren't the issue because this starter has been on the car for 4 years and worked without issue.

4. I'm thinking the cap and rotor were the problem. The day before, I had problems with the cap and rotor, and the car had sat for 2 weeks without driving prior to that, plus a temperature drop. I'm thinking that I got some moisture in the cap and maybe started the crack on the starter from that.

The engine is a pretty much stock LO5. Thanks, redneckjoe, for suggesting the starter support bracket. I will be getting one of those.

Thanks to all of you who replied! Seeing as there's no mechanical damage other than to the starter, I'm going to chalk it up to being a cheap chinese remanufactured piece of junk and replace it, as sofa suggested.

Thanks again!

 

Perfect opportunity to upgrade to the LT1 starter.