I just got off the freeway and while waiting for the light, there was a thunk and my engine died. It would not turn over with the starter. It would turn just a bit and then wouldn't budge.
Towed it home and started looking into it. Tried to turn the crankshaft from the pulley bolt and sure enough, it moves to a certain point, but no further. I can turn it backwards less than 1/8 around and then it binds up again.
I pulled the spark plugs to make sure it wasn't compression stopping it. Same result. Then I dropped the oil sump expecting to see bad news but everything looks fine.
My next step is to take off the timing cover to see if it's in there or if the seizure is coming from my camshaft. And after that, I'll pull the rocker covers.
Does anybody have ideas on what I should be looking for?

The engine did not overheat, there is no lost fluid, oil looked great, etc. I'm kinda stumped so far.

 

It could happen I guess if your crank sensor failed or some gas issue. Electrical? alternator stopped charging used up your battery?

 

you might want to pull the Serpentine belt off and try to spin it again.
i have seen frozen accessory cause an engine from cranking in the past

I would pull the rocker before the timing cover, if a timing chain goes it usually breaks,
it will cause the motor to crank supper fast as it has no compression

 

If all the above don't show anything, remove the front cover and see if the timing chain has broken or gotten so sloppy it jumped a tooth or two.
If it did, piston is hitting valve that is open.
drowssap, this is an interference engine, meaning the piston will hit the valves if timing chain breaks, and engine will have compression on any cylinder that both valves happen to be closed on. Since the engine will not budge at a certain point, it most likely is a valve open and piston hitting it, not allowing the crank to go further.
Not saying this is the case, but sure sounds like it.

 

Thanks everybody. I can't believe I didn't think to check the accessories. I guess I just assumed the belt would spin still. I sure hope this turns out to be the problem. I can't wait to get home and check.
I can see the bottom of the timing chain from having the sump off and what I can see looks good. But yeah. It's looking like either an accessory......or something in the top end.

 

I don't know this particular engine but It sounds to me like a piston hitting a bent or dropped valve.

 

It's definitely not an accessory issue. Bummer. I really don't feel like tearing this engine down again.
I'm waiting on a bore scope so I can just take a look in the spark plug holes. Maybe I'll be able to see what's going on in there. Or if it's the camshaft, I'll be able to look from underneath and see something. I'll update after I've looked at that.

 

check the starter motor too...

 

Have you done or had done any work to the engine recently?

It does sound very much like a 'dropped valve' but I hope not. Take out the spark plugs and check none have disintegrated and try access a small endoscope camera that will fit down the spark plug hole and take a looksee.

 

Have you pulled the valve covers to see if you have any broken springs, rockers, or keepers? If its a bent, or dropped valve you will have a loose rocker. It should be very apparent. You can also turn over the motor and if the rockers move then it isn't the timing chain.