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I have the loudest Elantra, please tell me why

Hi! First post.

I have a 2013 Elantra. It’s the car that I’ve learned about cars with. I haven’t done anything too heavy with it yet, but finally got to changing my own brakes, spark plugs, ignition coils and bulbs. Did a transmission flush. Hooray for me.

Recently, after I changed the plugs and coils, I had to take the thing on a 500-mile round-tripper, through Appalachia. To say that the computer wasn’t prepared to handle that so soon after having run rough for a couple of days (I was waiting for parts) would be an understatement, and the transmission, while shifting fine, kept missing its cues to do so. A mess, lots of blue clouds out the back end, got hot a couple of times. Not great, but it pulled through in the end and has been running fine since.

EXCEPT that now the car, which always had a little bit of a non-engine rumble to it, hums loud enough to drown out the radio when I get it past 40 or so.

The dash isn’t showing any lights, the tires are only a year old, the front brakes are the same age, the rear may need some maintenance but also just got a passing grade from the dealer so … yeah, i don’t know what this is about or what. It doesn’t sound like a bad catalytic converter, and it’s otherwise asymptomatic for bearings, so I’m kind of stumped.

Like I said, it drives fine minus what seems to be some lost fuel efficiency after running rough (I keep meaning to reset the computer but haven’t had the time), so this is just a weird one.

This does not sound like a vehicle that receives a passing grade. Got hot , blue smoke and not shifting correctly means you ned to have a mechanic really look this thing over.
Did you buy this thing used because it sounds like you may have a flood vehicle .

I don’t know but it only takes a few minutes of “running rough” or with a miss, to get one of the cats red hot and ruin it. I don’t know if that’s the case or not but smoke is not normal. I think someone else needs to take a looksee.

Good for you, well on the way to a experienced diy’er. If this humming sound occurs whether in gear or coasting in neutral (may not be quite as loud when coasting), and gets louder the faster you go, despite what you say, I’m still thinking the most likely cause is a bad wheel bearing. I suppose the obvious tests for wheel bearnings have already been done, axial and radial play, listening for scraping noises when hand turning the wheels, etc. Here’s the problem: Depending on the bearing failure mode, sometimes there are no obvious shop symptoms for wheel bearings, and the only way to prove it is the wheel bearing is to replace it.

Before going that route make sure the noise is associated with the car moving in gear or in neutral, and doesn’t occur when the car isn’t moving whether the engine is being rev’d or not.

no mention of miles.
i would not expect a 2013 to need plugs/wire/coils?
unless it has 100k miles and you thought it was not running well?
which is a red flag. new car. runs poorly?
you do minor tuneup and it runs the same? as in poorly still?

I think you got it exactly – the noise starts right around 40 and gets more intense (and even “rolls”) up to 60, and sticks around until the speed drops. I ran it on some open road and switched down to neutral, and it stayed with me. I haven’t heard any scraping yet, but I think I know which angle to approach first. Thanks boss.