Loud screech upon startup

I have a 2009 Hyundai Sonata which gets a sporadic high screech upon startup. I associate this sound the key left in the ignition after the car has already turned over. It will go away as soon as I shift into drive. Any ideas if this problem is with the ignition switch or starter? How difficult is this to diagnose as it only happens on occasion? Assuming it’s the ignition switch, might I be damaging the starter if it continues?

When was the last time you had your serpentine belt replaced?

I agree with Mike. Noise like that is more often than not the belt.

What makes you think it is starter related? Sometimes starters can make a horrible screeching noise when you start the car and the teeth aren’t fully engaging but you’ve already started the car. Is that the kind of noise you’re hearing?

The belt looks real good. Also, the noise goes away as soon as I get it out of park or neutral.

The belt LOOKS good ??
I’m a ‘‘car guy’’ and a parts guy at a shop. I know these things and do it for others as well.
My 08 expedition passed ‘‘inspection’’ at oil change a month ago.
Two weeks ago I’m driving home after work and a slight ‘‘bump’’ or delay occured as the a/c engaged but continued working.
A mile down the road the power steering gets stiff and warning lights start popping up like a christmas tree .
’’ feels like I broke a belt ??’’ I queery to myself knowing it ‘‘looked’’ good two weeks prior.
Pulled over in the Albertson’s parking lot and popped the hood…
Shreads everywhere ! It didn’t just lose the belt off the pulleys , it ate it for linch !
Gotta work now but I’ll post later as to why.

Almost impossible to tell if a belt is bad by a visual inspection.

And when you shift it out of park or neutral it puts a different load on the engine.

Does the squeak come back when you shift it back into park or neutral???

Does it happen every time you start the car??

I never heard of any ignition switch making a sound. A starter disengages when you release the key. In most modern cars it’ll automatically be released when the engine starts.

Not too many things can create a high-pitch sound. Usually a belt. But it’s difficult to diagnose over the internet and not actually hearing the sound.

Try this…have someone start the car for you and see if you can detect where the pitch is coming from.

Why did I shread a belt on a truck that gets regular inspections ?
Why will your good looking belt make noise ?
The ‘‘little bit longer’’ gamble bit me. YOU don’t have a little bit longer.

Rubber items harden with age , losing their elasticity. A fan belt loses its '‘grab’'ability.
Also, belts get compressed over time too. They’re no longer as thick as new.
Not grabbing well any more allows some slippage and that is your squeel.

Another cause of belt squeel will be a pulley that is on its way out causing resistance under a belt attempting to turn it, hence a squeel.

During the belt replacement work, test spinn all the pulletys it goes around feeling and listening fo rold bearings. Replace as needed.

In my case, my old hard and narrower belt JUMPED a groove or two as the resistance from the a/c compressor caused it to struggle.
After jumping over a coulple grooves the pulleys proceded to cut the belt with their edges. Then that loose piece gets tangled in the spinning remaing belt and pulleys yanking the rest of the belt off into the mele. ( it also broke a wire harness that I repaired. )

Look at and feel the NEW belt. Same with the old belt…remember this difference for future inspections.

It does not sound like a squealing belt to me; I’ve heard that sound plenty of times. It’s much more of a metallic sound, and sometimes I can hear it for a second as I turn the ignition key off.

A screech and a metallic sound don’t sound the same to me.

A metallic sound occurring during startup after you release the key…it might be the starter is not disengaging. But again - very difficult to diagnose without hearing the sound.

So the noise sometimes stays long enough for you to put the car in gear and the noise go go away?

Check how much play there is in your serpentine belt. More than an inch and it’s too loose. Hope it’s the belt. That’s an inexpensive fix. If it is the belt, you could spray the inner surface with rosin, but I would only do that until the weekend and then change the belt.

Maybe the starter bolts have worked loose.

The noise will remain until I shift into drive, then immediately stop. It will start up if i move it to park or neutral. Again, this happens very sporadically, but what quite loud when it does.

Could be an accessory or pulley bearing too. Maybe a mechanic’s stethoscope would narrow down where it is coming from. I’ve used a length of garden hose for this purpose in a pinch.

Could be the belt is glazed. Spray some water on the belt while it is making the noise and see if it goes away. Tensioner could be bad or accessory and your hearing the bearing squeal.

If the noise is present whenever the engine is running in neutral or park but disappears when any gear is engaged I would suspect that the torque converter flex plate is broken.

Yeah, flex plates can make horrible noises. When some of the flex plate’s bolts walked out of our impreza, it sounded a grinder. It was there all the time, though.
The other comment regarding the use of an automotive stethoscope makes sense. They are cheap and allow you to pin point the source of the noise.

I am revising my opinion. I think the starter is hanging and when you move it into gear it releases.

That was my first impression, @knf. Then a later post indicates that it is not a start up problem but rather a running in neutral problem since shifting into any gear silences the problem, then shifting out of gear causes the sound to return.

Agree with Mike, if it’s a metallic sound the starter gear may be sticking and hitting the gear teeth on the flywheel.