Hello,

Ever since I purchased my car (took delivery in Sep 2020), I noticed a fairly loud "ticking"-ish sound coming from the engine. It can clearly be heard in the cabin with all of the windows up, and it's even louder outside. The car has about 3500 miles now and otherwise runs fine (aside from a slight occasional misfire at idle which is apparently normal), but I'm concerned about this ticking sound.

Now, before everyone jumps in to say "it's the injectors, it's normal", I want to point out that it's definitely not the injectors. I know the car has DI, and I know what direct injectors sound like. I really don't mean to be rude, but pretty much every engine noise thread results in an "it's the injectors" comment, and most of the time they're right, but not in this case.

This ticking sound occurs at a rate of about 1/2 of the crankshaft speed and is most pronounced at ~1700 RPM, whereas the injectors tick at a rate of 4x the crank speed and are clearly audible if you put a stethoscope on the fuel line. The fact that this noise occurs at about 1/2 crank speed leads me to believe it's coinciding with a valve event. Or maybe the DI fuel pump (but I only hear the normal injector tick when I listen to the fuel line)?

Does your car sound the same?

I'm not sure what I expect to come of this considering the dealer isn't going to start ripping things apart to track down a mystery sound if there's no check engine light, but it would be nice to know whether other cars sound the same or not.

Here's a clip of my car with the engine held at 1700 RPM:

For what it's worth, there are a few other noises I've observed from the engine which I've deemed normal:
- When 4 cylinder mode is activated, I can hear the solenoids actuating to disengage the lifters for the 4 cylinders (it sounds like a gear grind in a manual transmission)
- When cruising in 4 cylinder mode, I can hear what sounds to be like knocking/pinging, as if the octane was too low. It's always done this, and I run 93.

 

^^^^
Put my sound volume on my computer speakers up high. Barely heard what you are calling a ticking sound.

I doubt you are hearing the hydraulic lifters collapsing in V4 mode. Might be hearing the exhaust valves that operate when it goes into V4 mode. Others have reported that. Since my 2 C7s where never in V4 mode- never used ECO with my M7s) and my C8 seldom sees V4 Mode (as I drive 90% of the time in Z Mode Power Set to Track) it never goes in that mode so can't comment on the valves, but IMO more likely.

With all the knock sensors in the LT2 unlikely you are hearing pinging from preignition, IMO. A computer would have retarded timing and richened the mixture when they detect knock and you would not hear!

Will be interested in what other's think. Some may have better high pitch hearing than myself!

 

To me it was not so much a ticking sound as a whirring sound--whirring like stuff going around and around in a rhythmic beat.

 

Sounds more like a compressor on a chest freezer, I didn't hear any ticking at all.

 

It could be that I am hearing the exhaust valves slamming shut when it enters V4 mode. I just know that I hear some type of metallic clunk. I figure that is normal. And yeah, I don't think the engine is actually experiencing detonation in V4 mode, but it just sounds like it. Regardless, both of those issues don't really concern me because they're really quiet.

My biggest concern is the "ticking" sound. It's hard to describe and even harder to accurately capture on video unfortunately. Ticking probably isn't the best word, but it's not deep enough to be considered a clunk I guess. It's just some type of periodic sound that follows the engine speed at 1/2 of the RPM.

I got another video of the car actually being driven. The engine "ticking" sound is most prevalent around 25-28 MPH right before the shift. You can also hear the sound of entering V4 mode at 43 MPH right before the video ends. This sound actually occurs right before the dash indicates V4.

If you listen to it with a cellphone, it's probably most audible. When I play it back with my sound system, the bass drowns the noise out.

 

Wow, I don't know what you folks are listening to, but I hear the ticking noise clear as day in his video. Unfortunately, I don't know what it is. I'd guess valve lifters, but really don't know, sorry. (Just wanted the OP to know I clearly hear what he is referring to.) [Note: I clearly hear it in the OP's 1st video. However, I do not hear any noises in the OP's 2nd video.]

 

Mine sounds the exact same. Like the 2 - 3 second mark and so on. Mine is a 2021.

 

Sounds like belt or pulley or water pump bearings?
Like a skidding metal on metal sound. Is that what you want us to hear?
The other ticking sounds are normal.
Video is too short. Does sound change with RPM? Any aftermarket drivetrain mods?

Forget about it and drive it till something breaks. That is what I would do in this case. Don’t chase it. Dealers do not have enough experience with this car yet.

 

Thanks. I know that it's at least an unusual sound. It may or may not be normal, but it's definitely there. In fact, I gave my friend a ride one time and he actually asked me if the car had a lifter tap (without me ever mentioning it). But then again, I'll post this on the various groups and everyone will say it's normal.

That's good to know. I hope every car sounds the same, but then I question it because...how can people not know exactly what I'm talking about then? It's pretty loud in the car. If someone asked me "hey does your C8 tick?", I'd immediately know what they're referring to.

I suppose "skidding metal" is accurate.

No mods at all. Sound follows RPM at a rate of 1/2. So at 1800 RPM, the sound occurs at a rate of 900 "beats per minute". At 1000 RPM, it's 500. I actually used a metronome to determine this lol

And yeah, it's either going to get worse and self destruct, or make this noise forever and continue running perfect. Time will tell. In the mean time, I'm gonna send it.

 

I can definitely hear it in the video. I can also say that my C8 does NOT make that sound.

 

So logically diagnosing along the tree, that measurement means that you just have to find the part on the engine that does the same multiplier.
So what does that? There are not many choices:
Only choices are engine + exhaust system. Not transmission, since the car does it when not engaged.
Can we completely eliminate the trany? Did you test it in neutral in addition to "P"?

1. Is there a pulley that only turns 1 revolution every 2 engine revolutions? Can't think of anything......
2. Is there something ON or INSIDE the engine that moves at this rate? Injector firing noise? Can't think of anything else.....
3. Is there an exhaust manifold leak on 1 cylinder that puffs every 2 engine revolutions? Exhaust leaks can sound like other things.

Is the car idling in V4 mode? If so, it is some kind of deactivation noise that disappears when the car is in V8? Doubtful, but asking.
I have heard fan belts sound like this, pulleys sound like this, and leaks sound like this in my long time on this spinning rock.
Maybe someone else can chime in. I am out of ideas.

 

I had the same noise it started at around 1100 miles. I also had the noise winding of the rear end it was a 2020. I sold the car and ordered a new one. The last thing I wanted was the dealer trouble shooting the car.

 

exhaust leak?


Kept listening almost sounds like maybe a bolt backed out somewhere and is being worn down?


Bring that thing in. Because whatever it is could become catastrophic and you'll be without it even longer.

 

I agree I hear ticking and what appears to be a very high idle.

 

I definitely can hear the ticking sound in the video as you stated. My C8 does not sound like that when it is idling. Not sure what your problem may be but something definitely does not sound right. Hopefully you can get your problem resolved.

 

One of the best tools I have, for things like that, is an old stethoscope with a 2' length of brake line as a probe. You can usually zoom in on the sourch pretty quick.

 

It might also have to do with the speakers on people's PCs or cellphones. I use my PC for editing audio & video. I've spent more on my Klipsch speakers than I care to admit. I can hear both the clicking sound and the "whirring" sound that others mentioned. I don't think that's a normal sound.

 

100 years ago (or so it seemed) in 1980 I had factory shop manuals for my 76 Corvette and they had said in the factory books to take a piece of hose and stick one end to your ear and move the other end around the motor to isolate where a noise is coming from. Works on idler bearings, alternator bearings, etc. too.

 

Yep have used that piece of garden hose! It works. But can buy this stethoscope at Harbor Freight for $5. The needle like end can get help isolate and exhaust port.

IF the analysis says the "tick" (which my old ears can't hear) is every other revulsion it should be able to detect an exhaust leak. If as I suspect (again assuming that every other revolution is correct) it's one noisy fuel injection nozzle that will be harder to pinpoint. However if just noisy may not every fail.

 

Let me know if you find out anything on this, My car has the same exact sound and always had. I took it in a few months back and they said that it is completely normal and said that another c8 they had on the lot had the same noise, so since then I have just ignored the sound.