After doing some research, apparently 2011 was the first year of Hyundai's new Theda direct injection gas engine. Now, after a few years they are becoming known as sludgers, prone to sudden and catastrophic engine failure/seizure. Hyundai is apparently denying as many warrantee claims as possible citing sludge due to improper maintenance, if the owner cannot prove that all oil changes were done and the proper oil and filters were used for each one. Looks like a big problem for owners.
First something doesn't add up with the story... so i think we are missing something.
Next, the alternator pulley is shaped funny due to some kind of design where the alternator does most of it's power generation when the vehicle is not accelerating, according to what i've been told.
The starter in these vehicles has a known achilles heel where a plastic fork that deploys the pinion gear fails often and it's possible that this could be stuck engaged?
Vehicle carries a timing chain.
I am not aware of any sludge issues with this motor. One would think that if it had known issues they would have revised the design by now as the 2.4L Theta is the workhorse of most of the lineup and has been that way for quite a few years now.
Starter being stuck engaged is one of the possibilities. Looks like the intake manifold has to come off to get at it.
Just type in "2011 hyundai sonata engine failure" in your search bar, many sites will come up including below.
You might want to inspect your Sonata for sludge to be safe. Just saying.
2011 Hyundai Sonata Engine Failure – Class Action ...
Chimicles & Tikellis is investigating a proposed class action lawsuit against Hyundai for alleged premature engine failure in certain 2011 Hyundai Sonata vehicles.
Broken engine mount leading to collateral damage I.e. Belts, hoses, throttle cable, etc?
Even if he slammed the gas down along with brake or revved the engine accidentally the car should have a rev limiter on it.
Does not appear to have any broken motor mounts or leaks or anything else wrong externally. The engine is seized up tight. Removed the serpentine belt and cannot turn the crank with a wrench. He did admit to adding 1.5 quarts after the fact, and it is 3/4 quart low now so it was over two quarts low when this happened. We did not remove the starter so there is a very slight chance that it could be jammed into the flywheel and seized, thereby preventing engine rotation, but I am not holding my breath on that. I did look in the oil fill hole and everything I could see with the flashlight was VERY clean. The poor kid is now exploring his options, none of which are good.
Thanks for all the replies.
wow - I'm driving the 2010 2.4L (75k now) and so far no issues.
Wonder what's different on the 2011 2.4 and why Sonata - what about others using the same engine.
Maybe mine is known for same issues - haven't checked into it....yet
Maybe since car had less than half it's oil in the crankcase (at least 2 1/4 quarts low), that it's 5000RPM wind up at about the same time the brakes were applied hard caused what little oil that remained to slosh away from the pickup thereby starving engine and causing seizure?