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Discussion Starter #1
First:
I have (and have had) a weird vibration at idle..it's definitely more pronounced when the alternator clutch is engaged (A/C on, or headlights on, in Drive with foot on the brake)
I've read HUNDREDS of pages on this subject...i've done all the scheduled maintenance on the car (2016 MD with 135k miles)...however, i've not replaced any of the engine/trans mounts.
I don't drive hard or anything crazy, although once I did go over a train tressel too quickly and actually got a little "air". (first time going down that road and no signs posted on it being **** near a ramp, haha)
So i've ordered a new Torque Strut (aka: Roll Restrictor) and i'm going to put it on this weekend.
Also, i'm going to replace my serpentine belt this weekend too (ordered a Krikut to help get it perfect), as it's the original belt and it's got 135k miles on it, so i'd say its good preventative maintanence.
Any other ideas on what I should be looking at for the vibration. (It's definitley a vibration vs. rough idle, as my rpm needle is DEAD solid still, and it sounds like something it definitely vibrating underhood; although i've checked everything and there's no loose bolts or anything like that)
 

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When changing the serpentine belt, start the car when the belt is off to see if any vibrations. That belt drives the water poump so you can't run it for an extended period.
 

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Seized clutch pulleys can cause vibration




And sunken hydraulic engine mounts I guess, could be another to check. If the bracket to the motor is sitting hard on the rubber stop then I'd say the mount has collapsed, also underneath the bladder would have expanded full of the fluid that's contained within the mount.


 

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Discussion Starter #4
If the alternator clutch pulley was seized, wouldn't I know it? (aka: it wouldn't be working at all to keep the battery at the correct voltage)
Also, on the upper engine mount, it LOOKS to be OK? (I'll go get a picture of it right now)
 

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Discussion Starter #5
Yes it's dirty.
So it looks like there's probably a solid 1/4" between the mount and the rubber (I don't know what a brand new one installed gap would be)
441792


Also, I used the KriKut on my belt...and either I'm an idiot and can't get my hand in the correct place to actually USE the guage, or my belt has a little less than 100ftlbs of tension, as the guage just goes max (it only reads down to 100lbs)
I mean; I'm definitely going to go get a new belt and replace it later today...but I just want to be sure i'm actually using it correctly.
 

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Doesn't the car have a belt tensioner...why do you need to check tension? Another question, isn't the alternator always driven? The only possible clutch would be on your compressor.
 

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Discussion Starter #7
Doesn't the car have a belt tensioner...why do you need to check tension? Another question, isn't the alternator always driven? The only possible clutch would be on your compressor.
No, and No.
the MD Elantra uses a bolt to set the tension on the serpentine belt (I thought cars went to automatic tensioners when they went to serpentine...alas I was wrong)
also, the elantras use a load sensing alternator...so it just free wheels until you need it, and a small Valeo clutch kicks in.
look under your hood sometime haha
 

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I'm glad mine doesn't have either of those "engineer's wet-dream"! :eek:
 

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Discussion Starter #9
So I swapped out the belt.
The OEM belt looked PERFECT, but it seemed to be less than 100lb's of tension...
On the new belt, I tightened the adjuster bolt more, and verified it was 150lbs of tension (right in the middle of factory spec)
The vibration is still there; but i think it's just how elantra's idle.
 
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