Engine/Transmission Rattling sound at Cruising speed

New poster here. Need assistance.

(I did try to look up for my issue before posting and I could no find something close enough to my issue. So here it goes.)

We have purchased a new CX-9 about a month ago. On a long trip recently, after a few hours of driving (engine was warm, conditions were great, road was decently paved and flat), I noticed a rattle/vibration under the car. One similar to a flat tire, or going over a corrugated road.

Vibration is felt through the middle console and has nothing to do with the road as I'm driving over a freshly re-asphalted one at the moment. I pulled over, checked my tires, nothing. I start to drive again, and as I get in higher gears (4th, 5th and 6th) it gets just louder, at pace with the car speed. I pull over again, stop the engine, inspect the car. Nothing. Drive again, it was gone.

Problem resurfaced Monday. Very, very, very noticeable vibration. Unmistakenly not normal. So I audited the issue a bit more while driving, knowing it was an intermittant issue. In acceleration, it is fine. As soon as I stop pressing the gas and let the car cruise, not braking mind you, just letting the car decelerate on his own accord, it starts vibrating. I press the brake, and I feel the vibration still, but not intensifying. I ruled out the brake. In 4th I fell it, in 5th I feel it more, in 6th, you feel you are about to lose a wheel.

It is not felt more through the pedals, nor the steering wheel. I would say it feels like it is right under the middle console. In acceleration, the clanking/vibration abates and you barely feel it. But as soon as you let go of the gas, it comes back with a vengeance.

Got the car to the dealer and they are to this point trying to reproduce the issue with no success. As a side note and a future rant, I was also told that unless they find an issue, Mazda Canada does not reimburse the diagnostics fee (about $72).

I should have mentionned that I'm not a car guy so I'm a bit of a newbie when it comes to them. Sorry if I cannot explain the issue better.

Kingo

Edit: If I should have posted this in another foruym, let me know and I'll move it.

Sounds to me like a tire out of balance. Sometimes that is only noticed at higher speeds. Maybe one of the wheel weights fell off.

Well, I can't really rule it out, but it would surprise me.

If indeed it was an unbalanced tire, due to a lost weight or not, then the problem would be persistant and indeed at a certain frequency (speed), it would re-appear most of the time. Unfortunately, this problem is not easily reproducible. Moreover, the vibration is quite significant - then again, not knowing any better, maybe an unbalanced tire could indeed produce this type of vibration, but I never felt it that strong.

Also note that it is present at most speed and gear levels, dissappears with braking or acceleration, but cruising (letting go of the gas pedal) gets it on.

Thanks for being helpful and trying to give me insight on the issue.

I called Mazda and they still have it in and not localized the problem.


On a side note, I called Mazda Canada and they refuse to confirm either way if it is indeed their practice to refuse to re-imburse Diagnostics unless a manufacturing issue (part) is identified. I'm on my own.

UPDATE

Sorry if this sounds as my own personal little thread, but I want to fill you up with all details to help me pin-point this.

So the Techs were apparently taking this very seriously. They did a few miles of road testing to no avail. The issue did not come back. They put it on the lift, inspected everything known to a car mechanic - from transmission, to tie rods, to wheels and tires, to brakes, to differential, etc...

After all that they did a second road test, still not able to reproduce the issue.

So I am confident they did their job. I also was not able to reproduce the issue this morning, but I know it is there. These are probably the damnest issues a mechanic can deal with.

On my non-official mini rant, I called my sales guy who talked to the service Manager who talked to the service rep and...I won't have to pay for the diagnostic, they'll absorb it locally.

I hope that next time this issue happens, I'm close to my dealer and during working hours to get a guy up in my car so that he can pin-point it with his experience.

This thread is still alive, if people have lived this issue. If I get more updates, I will post them. But i'm still very curious to know if I am the only one with this bizarre issue.

It does sound like something rubbing on the driveshaft...especially since you mention it happens more during deceleration, i.e. the driveline is moving?

I had an issue with my other car where I would get this awful vibration/rubbing noise when taking fast left turns (i.e. like getting on an on-ramp), or when shifting the car abruptly into a lower gear. It would not happen any other time. So something in the driveline was hitting something, I believe it might have been muffler pipes on the driveshaft. Dealer never found the issue, it took an independent shop to notice it.

They couldn't find anything. On the Work Order, I can read that they tightened a loose motor mount bolt. Was this the cause of the issue? Or was this the ploy they used to get Mazda to pay the Diagnostics. Time will tell.

Since this issue happened only 4-5 times in the last two months, I will give it a few weeks before I can comment back on this issue.

My 2008 CX9 with 1800 miles with the same problems was brought in yesterday to the Mazda dealer in Ramsey NJ. Luckily it made the same sounds at about 40-50mph (or anytime above 4th gear) with the mechanic when he test drove it. Well it seems the whole drivetrain needs to be replaced. In addition, it is not the first one they have seen with the 2008 CX9 GRAND TOURING that has the same problem. HMMM I smell a recall coming.

We are having the same sort of issue with our 08 GT AWD. The same type of vibration you are referring to, but ours is noticeable between 1.5k and 2k rpm and when cruising lightly on the accelerator. It is fine when accelerating and even coasting. We have an appt. at the dealer on 7/30, so we will see what they have to say or what they might find. They are not a big dealership, so I might be the first one in with this complaint.

noel0511 said:

My 2008 CX9 with 1800 miles with the same problems was brought in yesterday to the Mazda dealer in Ramsey NJ. Luckily it made the same sounds at about 40-50mph (or anytime above 4th gear) with the mechanic when he test drove it. Well it seems the whole drivetrain needs to be replaced. In addition, it is not the first one they have seen with the 2008 CX9 GRAND TOURING that has the same problem. HMMM I smell a recall coming.

Click to expand...

I doubt it is a recall issue, though it is one of the more common drivetrain complaints in the CX-9. I'm certain they won't be replacing your entire driveline, which includes engine, transmission, transfer case, torque converter, and axles. Most likely, your problem lies in one individual component, not the entire driveline.

At best, this driveline vibration might generate a Technical Service Bulletin (TSB), but not a recall.

Update

Nope, the surprising, rather concerning vibration felt under the car has not come back. But a new issue surfaced.

Since they tinkered with it less than a month ago, I noticed that when taking a sharp turn while accelerating, the car vibrates. Again, I am such a dummy when it comes to car mechanic that I cannot explain it better or self-diagnose what this is.

At first it was barely noticeable, and I thought I was just too critical. It is mechanics after all. But now it is felt clearly and this time it is repeatable. I just have to get in a big parking lot (or an onramp), cramp the wheels for a regular 90o turn, slightly accelerate and there it is, a cleanly felt rattling vibration. Both sides. So I'll get it in again.

Kingo said:

Update

Nope, the surprising, rather concerning vibration felt under the car has not come back. But a new issue surfaced.

Since they tinkered with it less than a month ago, I noticed that when taking a sharp turn while accelerating, the car vibrates. Again, I am such a dummy when it comes to car mechanic that I cannot explain it better or self-diagnose what this is.

At first it was barely noticeable, and I thought I was just too critical. It is mechanics after all. But now it is felt clearly and this time it is repeatable. I just have to get in a big parking lot (or an onramp), cramp the wheels for a regular 90o turn, slightly accelerate and there it is, a cleanly felt rattling vibration. Both sides. So I'll get it in again.

Click to expand...

All vehicles make some noise when the wheel is turned all the way to one side or the other. It is the sound of the power steering pump under load, generally accompanied by a loss of RPM (thus making vibration even more pronounced).

However, it is possible that your vehicle may have a bad bushing or steering knuckle (or suspension damage not immediately obvious such as a slightly bent control arm or drag link), and it may reassure you to have the dealer take a look. Just, don't be surprised if what you're experiencing is a normal operating characteristic of the vehicle, and that's what the dealer tells you.

Most of these vehicles have been relatively problem-free. At 2,500 miles, my only issue has been a smear inside of my r/s headlamp bezel, and that was replaced under warranty. First vehicle I've owned (including Mercedes, Honda) that's been so trouble-free, although it's too early to predict long-term reliability, initial build has been excellent. I worked for GM 14 years and took a buyout this year, I can tell you some horror stories, all 100% true.

Thanks for your reply. I will have it checked as it wasn't present before. But since this is a reapeatable 'issue' I will have the mechanic accompany me for a ride (well, i'll let him drive) so that I have confirmation if this is an issue, or my imagination.

Kingo said:

Thanks for your reply. I will have it checked as it wasn't present before. But since this is a reapeatable 'issue' I will have the mechanic accompany me for a ride (well, i'll let him drive) so that I have confirmation if this is an issue, or my imagination.

Click to expand...

Sounds like a plan.

A quick update on our issue. The dealership found there is a bearing that supports the rear drive shaft since our vechicle is AWD. After contacting Mazda tech support, they located the bearing and found it is cracked. They seemed to indicate that this is a known problem, but it also sounded like they were replacing the rear drive shaft. Once we get the vehicle back, I'll post what the repair was.

badself said:

All vehicles make some noise when the wheel is turned all the way to one side or the other. It is the sound of the power steering pump under load, generally accompanied by a loss of RPM (thus making vibration even more pronounced).

However, it is possible that your vehicle may have a bad bushing or steering knuckle (or suspension damage not immediately obvious such as a slightly bent control arm or drag link), and it may reassure you to have the dealer take a look. Just, don't be surprised if what you're experiencing is a normal operating characteristic of the vehicle, and that's what the dealer tells you.

Most of these vehicles have been relatively problem-free. At 2,500 miles, my only issue has been a smear inside of my r/s headlamp bezel, and that was replaced under warranty. First vehicle I've owned (including Mercedes, Honda) that's been so trouble-free, although it's too early to predict long-term reliability, initial build has been excellent. I worked for GM 14 years and took a buyout this year, I can tell you some horror stories, all 100% true.

Click to expand...

I want to hear them!! (hahaspit)

noel0511 said:

My 2008 CX9 with 1800 miles with the same problems was brought in yesterday to the Mazda dealer in Ramsey NJ. Luckily it made the same sounds at about 40-50mph (or anytime above 4th gear) with the mechanic when he test drove it. Well it seems the whole drivetrain needs to be replaced. In addition, it is not the first one they have seen with the 2008 CX9 GRAND TOURING that has the same problem. HMMM I smell a recall coming.

Click to expand...

sorry I meant driveshaft

I have been too busy to get the car in until now (was on an extended vacation and used another vehicule).

But car is at Dealership this morning. Got the Mechanic's Supervisor for a road test and he acknowledged the issue. He is confident it is the Transfer Box (I may be misquoting here, but I think this is what he referred to). He said it is not behaving normally and the rattling/knocking reverberation propagates from the box to the structure right under the armrest and this is how we can feel it there.

He said he will investigate with Mazda to see if other tech's have reported a similar issue. He said he will change the oil (if he can) and if not will change the whole box.

I will update this thread as I get news.

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Update: Got a call from Dealer, it is not the Transfer Box, it is the Drive Shaft. The Service guy I talked to on the phone had no more details than relaying information he had from his mechanic:"It is a driveshaft issue, it needs to be replaced". They called a part in and they will replace the whole shaft assembly with a new one. They are keeping the car as the part will arrive only tomorrow morning. Car has about 6,000 K (or about 3,600 miles).

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Part is backordered. They will get it in about 2 weeks. Next appointment is set for September 22nd. They say it is not a safety concern.

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Guess what. I show up at the Dealer this morning (with the typical inconvenience or getting the two kids in gear, with my wife waiting to drive me to work in the other car) and you guessed it. A classic. They don't have the part - it is backorder another 10 - 15 days. But noooooo, they wouldn't think of calling me to tell me not to show up for my appointment, they forgot to call. Bad service so far. Next update when I get it fixed. Knowcking is more present than ever now with the colder mornings.

OK so final update.

Car was at the dealer yesterday morning. Side note: I heard some of the guys mentioning that the part was not new, but 'taken' from another car in their lot, cause the delay (due to the backorder) would have been too long. Cannot confirm this, neither do I care as long as it is a good part.

So. Car was in for a few hours only. I got called by mid-day to be told that it was ready. I picked it up at the end of the day and....miracle! It runs so smooth now! I guess that now that I hear/feel what it is suppose to be like, then definitively this car had serious issues. It never was that smooth, even in the first few days. This car now doesn't make a sound, rumble, vibration or whatnot anymore.

So (after only 1 day mind you) the problem has totally gone away.

Glad again. Now I can enjoy the ride!

Hi, I have a very similar issue. I have a 2003 Mazda 6 (Atenza) AWD and it has developed a vibration when decellerating and turning at the same time. It some times sounds like it's coming from the right front but I drove as a passenger in the back last night and it sounded like it was drive shaft related.

I'm crawling all around underneath trying to find something loose but there doesn't seem to be anything obvious. I'm thinking it sounds like it's related to the drive shaft hanger bearing causing vibration through the drive line, exhaust and heat shields.

When I shake the drive shaft with force at the hanger bearing I get a small clunk noise but not obvious play.

Can anyone offer more on this?