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2016 Mazda 6 making grinding noise

9K views 12 replies 7 participants last post by  nitewulf 
#1 ·
Car is 3-1/2 years old with 27k miles. A few weeks ago I noticed a rumbling or grinding noise when accelerating from a stop. If you let off the gas slightly, it's there too. I have had the car since new and I know this isn't a normal noise. I turned it in to the dealer Friday and asked them to check it out. I asked them to check the heat shield and exhaust including brackets and gaskets. They said all were fine and test drove the car. They couldn't find anything wrong. The regular warranty is up, but not the power train warranty. Where should I go from here? Should I call Mazda and see if they can arrange for another dealer to look at it?


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#2 ·
I would try another dealership and/or independent shop (you trust) and pay diagnostics - once you have diagnostics, see if it's something dealership will cover and bring them diagnostics paper. Depending on what's wrong, either get it fixed at the dealer or at the shop. Wheel bearing noise?
 
#3 ·
My first guess would be wheel bearings as well. Not uncommon for wheel bearings to take a hammering considering the 2016 GT runs on 19 inch rims and low profile 45s especially in winters where there are potholes everywhere. See if you can replicate the noise when the car is idling and take it across the rev range, if its only making the noise while in motion, i would start with the wheel bearings.
 
#4 ·
I thought of wheel bearing noise. The noise is not constant, though. If you have ever driven a manual shift car and shifted into too high a gear for the speed you are going, the engine lugs and creates a growling sound. Of course, this car is an automatic, but it almost seems like maybe the gear ratio is not right. The problem is finding a competent mechanic that can listen to the noise and properly diagnose it. I'll post if and when I get it resolved.

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#5 ·
Updare:

Took the car to the dealer today for a 2-1/2 hour diagnostic check for which I paid $150. I went on a test drive with the mechanic. He heard the noise, but couldn't find the source so I'm back to square one. He checked the motor mounts, pulleys, torque converter, transmission including fluid level, heat shields, wheel bearings and complete exhaust system to include brackets hangers and gaskets. They will call Mazda for ideas, but I'm not expecting much. Guess I'll trade for something else once it's paid off. Car was flawless up to a month ago.

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#8 ·
Turned out to be the belt tensioner. At least it's quiet now. I think next time I will try an independent shop since it's out of the regular warranty. I ended up paying quite a bit for diagnostic time, before they isolated and fixed the problem.

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#12 ·
Thanks for keeping us updated and glad that you found someone that was had the technical knowledge to help properly diagnose and fix the issue. Sorry, we couldn't help from afar, but sharing your experiences might help someone one here with same/similar problem, which is the point right? I would make sure to keep a relationship with that mechanic and hope you feel better about your M6.
 
#10 ·
Easiest way to check bearings is to get the car on some (sturdy) jack stands only high enough to get the wheel off the ground, grab the wheel with one hand at noon, one at 6, and try to shake it. Do the same at 3 and 9.

If you can make the wheel move even a tiny bit back and forth, it's likely a bearing.
 
#11 ·
It's somewhat difficult to isolate a bearing this way; modern "flat" (non-tapered, sealed) bearings frequently fool you when you try to use the usual method (e.g. sharp cornering); the problem is that it will often lead you to believe the wrong side is where the fault is.

One way that is almost-always effective, however, is to put the car on stands, start it, put it in the top gear at idle (easy in a manual, obviously) and then use a mechanics' stethescope on the top of the strut mount or, even better if you can get to it, on the strut itself. As the knuckle is bolted to the strut the mechanical transmission of the noise will almost-always be instantly obvious and will localize it to either the CVs or bearing. Since you have to pull the half-shaft anyway if it's the CV you stop there although USUALLY if the CV is the source you get that characteristic "clicking" noise when making sharp turns even at very low speed -- so if you're checking this you usually are pretty sure the CVs are not involved.

It requires GREAT CARE to do this, however for obvious reasons since the wheels/tires will be moving and if you get anything caught in there VERY severe injury is pretty much certain.

If you have motion with a shake and the tie rods and such are not moving at all (that is you're not getting movement by motion through the steering rack) there are a number of things that can be bad, including tie rod ends and ball joints, along with the wheel bearing. You need someone to look CAREFULLY at exactly what is moving while you shake it and if the wheel bearing is bad to the point that you can get visible motion in this way it's in extremely bad condition and the car shouldn't be driven at all as what's left of the bearing may disintegrate without warning.
 
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