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Loud pulsating grinding noise from underneath the car

Tiny
YOURMINKY
  • MEMBER
  • 2000 HYUNDAI ELANTRA
  • 2.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 105,000 MILES
The front driver side wheel has a new bearing on my car. When I drive the car it makes a loud pulsating grinding noise when the engine is cold. The grinding noise appears when the car hits twenty mph and goes away after a few minutes of driving and does not return until everything is cold again. The noise is even louder if I rotate the steering to the right. Rotating the steering to the left makes the noise almost go away. It started happening a few days after all four tires were balanced and rotated. The pulsating grinding noise is new, before it was a constant humming grind when the engine was cold, not so loud, that eventually went away after driving for thirty minutes or so. The weird part is that the new pulsating grinding noise goes away after driving the car for a minute or two. Is it related to alignment, tire balancing or something else?
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Friday, December 22nd, 2017 AT 4:52 PM

6 Replies

Tiny
WRENCHTECH
  • MECHANIC
  • 20,758 POSTS
It is probably a bad tire that was brought forward in the rotation and is now under the weight of the engine and trans-axle.
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Friday, December 22nd, 2017 AT 5:05 PM
Tiny
HARRY P
  • MECHANIC
  • 2,292 POSTS
Does the noise change at all when you apply the brakes? Because I am thinking about the possibility that one of the brake pads is completely worn down and just rubbing on the rotor. That could explain the grinding and the fact that the noise changes with turning the wheel.

Also, if they just replaced one of the bearings, the other could be failing. There is an inner wheel bearing and an outer wheel bearing. Generally when one goes bad, the other is not too far from going bad as well.
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Friday, December 22nd, 2017 AT 7:39 PM
Tiny
YOURMINKY
  • MEMBER
  • 106 POSTS
The brake pads and shoes are all new. I will check the relation of the noise to applying brakes and update.
I changed the front driver side wheel bearing because of a different issue. Previously, the tires/wheels had a humming noise which increased and decreased when I turned the steering clockwise or anticlockwise. Judging by the nature, experts told me it is the front driver side wheel bearing that is bad and I changed that wheel bearing. However, that did not fix anything. The noise was still there. I was told to rotate tires. All four tires were rotated and balanced six days ago. The pulsating, short-term, dragging noise started three days ago.
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Saturday, December 23rd, 2017 AT 9:17 AM
Tiny
HARRY P
  • MECHANIC
  • 2,292 POSTS
Hmm. A bad CV axle can make some horrible noises (clicking, popping, grinding). But that usually is not something that goes away when the engine gets warmed up. Since it is speed and temperature related, I am thinking that it might be the transmission itself making that noise, grinding gears. When the car is warmed up, check the transmission fluid. If it is black, then that is your problem.
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Saturday, December 23rd, 2017 AT 6:59 PM
Tiny
YOURMINKY
  • MEMBER
  • 106 POSTS
Thank you for your comments.
I tested and the pulsating grinding noise has no relations with braking. When it happens, during that few minutes, the noise is increased and decreased by the rotation of the steering wheel only. Going straight creates a dull pulsating noise. It starts a few seconds after the cold car starts moving and hits twenty mph. Speeding up over thirty five mph or slowing down under fifteen mph causes the noise to go away.
Steering counter-clockwise (left) increases the loudness and steering clockwise (right) decreases the loudness.
The pulsating grinding noise is similar to beetle larva eating wood type noise, there is about half-second interval between pulses.
People told me to re-rotate the tires again just in case it is bad cupped tire issue. It is zero degrees outside. I will either rotate it myself when it is a bit warmer outside or take the car to a tire store to have them rotate and update this thread.
Regarding the transmission fluid, eighteen months ago I removed three quarts and added 3.75 quarts of total of AT fluid because I thought the fluid level was low. I used Valvoline MaxLife Multi-Vehicle Automatic Transmission. According to Valvoline, it is compatible with SP-II, SP-III and SP-IV which is used by Hyundai. I checked the fluid level two months ago and found the AT fluid level was actually too high. I removed 1.75 quarts and added one quart new AT fluid two months ago. The fluid level was in between the lines on the dipstick two months ago and I don't have a AT fluid leak. The fluid is very dark brown. Experts told me the fluid gets dark after several months on Hyundai and that is Okay.
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Monday, December 25th, 2017 AT 12:16 PM
Tiny
HARRY P
  • MECHANIC
  • 2,292 POSTS
The fluid changes from red to a light brown/amber color under normal operating conditions for Hyundai's. I would worry a little bit about it being dark brown. When you checked the fluid, did you feel any metal shavings or grit in the fluid that came off of the stick? And did you warm the transmission up before checking it?

The only way to get an accurate reading of the fluid level is to start the car and drive it a few miles, and then check it, while the engine is still idling. That gets the fluid into the lines and various nooks and crannies, which lowers the reading on the stick a good bit.
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Tuesday, December 26th, 2017 AT 2:53 AM

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