Help! 2021 CX-5 undiagnosed engine knock

[alexdemench]

Hi everyone, I hope you can help me out - this is driving me nuts.

I have a 2021 CX5 GS, skyactiv engine. Purchased new, all regular oil changes by dealer.

There's this engine chugging/knocking sound that varies with RPM, sounds almost like a diesel engine when it's there. No engine lights have ever come on.

But it's very intermittent. Will be present in summer or winter. More noticeable in the cold, or just after starting, but it'll last through my 20min commute. Happens in the summer in 20*C too.

I've brought it to the dealership twice but each time it isn't there when they examine it and tell me they don't see anything wrong.

I'm reaching the end of my warranty period and really worked this will cause premature engine failure and brick my car :/

Video attached and I'll add some other videos of abnormal/normal sounds in the comments.

Anyone have ideas or advice?
Thank you so so much in advance!

 

[alexdemench]

Same noise in 8*C, several months earlier

 

[alexdemench]

Normal (to me) revving engine

 

[Moonlighter]

Have you shown these videos to the dealer?

I did that when I had a intermittent issue with my previous CX5 and tha5 was all it took for them to act.

 

[alexdemench]

Have you shown these videos to the dealer?

I did that when I had a intermittent issue with my previous CX5 and tha5 was all it took for them to act.

Yeah emailed these videos and showed in person, but they say that unless the noise is there for them to examine, they can't really do anything :/
And it's so loud in the maintenance bay that I can barely hear the video/engine noises when I'm there myself.

I'm hoping someone here can point me in the right direction in terms of what it could be, so I can give them more specific direction...

 

[Mazdiod2]

I can hear that it's not normal. Does it vibrate more when it makes this noise?
You say intermittant. How often is that?

 

[alexdemench]

I can hear that it's not normal. Does it vibrate more when it makes this noise?
You say intermittant. How often is that?

No obvious vibration or lack of power that I've noticed. It'll come on for a period where every time I start it, it's there for a day or a few days. Then might go away for weeks at a time.

It's happened winter-summer-fall. Now this is the 2nd winter. Hasn't seemed to affect overall driveability and function, but I'm worried this will lead to some major issue in the powertrain prematurely.

I just can't think of what would be so intermittent like that :/

 

[Moonlighter]

Yeah emailed these videos and showed in person, but they say that unless the noise is there for them to examine, they can't really do anything :/
And it's so loud in the maintenance bay that I can barely hear the video/engine noises when I'm there myself.

I'm hoping someone here can point me in the right direction in terms of what it could be, so I can give them more specific direction...

Escalate to Mazda HQ.

Thats a pathetic response from the dealer.

 

[Odrapnew]

Does this have cylinder deactivation?
Could that be a cause?

 

[ceric]

Maybe have someone rev the engine and you can try to pin point source of noise under the hood.
What I hear is mechanical friction...
Could also be heat shield again a moving part.
I would start by locating source of noise along the belt.

 

[sm1ke]

Escalate to Mazda HQ.

Thats a pathetic response from the dealer.

This is the next reasonable course of action.

It's ridiculous for a dealer to require the car to be making the noise at the time of inspection when you've already documented the behaviour and established that it occurs intermittently. If you've already escalated the issue to the Service Manager, and they are still unhelpful, let them know you will be contacting Mazda Corporate as that is the next step as documented in your owner's manual. Then contact Mazda Corporate and open a case with them, providing all the necessary information and evidence.

That noise doesn't sound normal at all. It seems to me that the dealership is lazy, or worse yet - they're waiting for your warranty to run out so that they can charge you for an out-of-warranty repair.

I had a similar experience when my rear diff started making noises. It was intermittent, and when I took it to the dealer, they couldn't replicate the clunking noises and sent me on my way because there were no stored codes. Weeks later, my rear diff failed completely.

 

[ceric]

Maybe go to another Mazda dealer if not too far away.
In general, dealers don't like to debug rattles or noises.... not very cost effective to them.

 

[Odrapnew]

First off, I agree that is not a good sound and does sound like it’s in the engine.

Now, I usually side against dealers, but I sort of agree with them in this case.

Yes, the noise is captured on video, but how do you expect them to diagnose that noise if that’s the only evidence? There might be an engine code stored, so they could do a scan, but if no code and no noise, tough to pinpoint.

What if the diagnosis is dependent on the noise actively being present? It might be something that needs to be ‘caught in the act.’

What if it’s inside the transmission, but from video sounds like engine?

Are they supposed to start taking things apart until the find something?

I’m grasping at straws here, but that’s what the dealer would have to do if the noise isn’t present during their diagnosis.

 

[sm1ke]

What does it sound like from the engine bay when the noise is present? Anything like this?

 

[sm1ke]

First off, I agree that is not a good sound and does sound like it’s in the engine.

Now, I usually side against dealers, but I sort of agree with them in this case.

Yes, the noise is captured on video, but how do you expect them to diagnose that noise if that’s the only evidence? There might be an engine code stored, so they could do a scan, but if no code and no noise, tough to pinpoint.

What if the diagnosis is dependent on the noise actively being present? It might be something that needs to be ‘caught in the act.’

What if it’s inside the transmission, but from video sounds like engine?

Are they supposed to start taking things apart until the find something?

I’m grasping at straws here, but that’s what the dealer would have to do if the noise isn’t present during their diagnosis.

As long as the customer is okay with diagnosis fees, the dealer should have at least offered to contact Mazda Corporate to see if there have been any reported issues or TSBs related to this noise. The car is still under warranty and the dealer should be addressing any relevant concerns by using the resources available to them.

What I'd personally expect is to pay for diagnosis fees out of pocket. If this turns out to be a warranty issue, the diagnosis fees should be refunded.

 

[Odrapnew]

As long as the customer is okay with diagnosis fees, the dealer should have at least offered to contact Mazda Corporate to see if there have been any reported issues or TSBs related to this noise. The car is still under warranty and the dealer should be addressing any relevant concerns by using the resources available to them.

What I'd personally expect is to pay for diagnosis fees out of pocket. If this turns out to be a warranty issue, the diagnosis fees should be refunded.

I agree with that.

It could be as simple as popping off the valve cover and seeing something in the upper valvetrain, or it could be much more involved. I think the crappy part is not knowing the potential diagnosis cost. Maybe a $100 maybe a $1000.

I know when I've had warranty work, they stated the diagnosis fee up front in case the repair is not covered by warranty.

 

[alexdemench]

Does this have cylinder deactivation?
Could that be a cause?

What does it sound like from the engine bay when the noise is present? Anything like this?

Thanks for the video. I don't think it's the same as in this video. This vid is much higher frequency and higher pitched. Sounds like metal rubbing on metal.

I think it 'my noise' as a CHUFF-CHUFF-CHUFF sound. Probably like 3-5Hz at idle and accelerates as I rev the engine.

Someone mentioned whether it could be related to 'lifters' but tbh I don't know enough about engines to know what that means...

 

[alexdemench]

First off, I agree that is not a good sound and does sound like it’s in the engine.

Now, I usually side against dealers, but I sort of agree with them in this case.

Yes, the noise is captured on video, but how do you expect them to diagnose that noise if that’s the only evidence? There might be an engine code stored, so they could do a scan, but if no code and no noise, tough to pinpoint.

What if the diagnosis is dependent on the noise actively being present? It might be something that needs to be ‘caught in the act.’

What if it’s inside the transmission, but from video sounds like engine?

Are they supposed to start taking things apart until the find something?

I’m grasping at straws here, but that’s what the dealer would have to do if the noise isn’t present during their diagnosis.

Yeah it's a tricky issue. I agree it doesn't make a ton of sense to completely dismantle the engine looking for it. But I'm just so worried about losing warranty coverage and being out of luck when a problem rears its ugly head.

I wouldn't mind the option of paying upfront for diagnosis, and if something is found, getting reimbursed from warranty. That sounds fair.

I wonder if it would be worthwhile emailing Mazda corporate to document that the issue arose within the warranty period and asking for their advice.

 

[sm1ke]

Thanks for the video. I don't think it's the same as in this video. This vid is much higher frequency and higher pitched. Sounds like metal rubbing on metal.

I think it 'my noise' as a CHUFF-CHUFF-CHUFF sound. Probably like 3-5Hz at idle and accelerates as I rev the engine.

Someone mentioned whether it could be related to 'lifters' but tbh I don't know enough about engines to know what that means...

Right, that's why I asked what it sounds like from the engine bay. The cabin muffles a lot of noise so a chuffing noise would probably sound different from outside.

I wonder if it would be worthwhile emailing Mazda corporate to document that the issue arose within the warranty period and asking for their advice.

As I recommended in a previous post, you should absolutely do that. The process, along with contact numbers, is all outlined in your Owner's Manual.

 

[GrampaSlade]

Sounds just like my Silverado on startup. Piston slap.