[Fixed] Buzzing/Rattle Noise around 4K-4.5K RPM During Cold Start

[itsgr8]

Long story short:
- If you hear buzzing noise at around 4K-4.5K RPM during cold start, and it's coming from the passenger side engine bay, it's highly likely due to the red engine cover rattle.
- To fix, take out the 2 left bolts (when facing the engine), either add an extra washer, or use electric tape to wrap around the smooth portion 1-2 times, then retighten the bolts. Confirm the engine cover is firmly pressed down to the engine.

Full Story

This rattle/buzzing noise has been bothering me for quite some time. It occurs only when:

1. Engine is cold (first 10 min of drive)
2. Rev to 4K-4.5K RPM -- only this RPM range, not below 4K, not above 4.5K
3. It's not from the cabin, sounded like coming from the passenger side of the engine bay

I brought my car to dealer. They claim they could not reproduce it themselves (I left my car with them for a full day so that they can drive it cold). When I test-drive the car with their "master tech", I was able to produce it, but the tech has no idea what it could be, and refuse to look further, claiming I should never rev the engine that high and should always change gears below 3K RPM.....

I was so upset with the noise (and the dealer's attitude), because this is my daily commuter and I hear the noise at least twice a day. I was even ready to trade the car in at one point.

Recently I started doing some light mod: shifter, brake pads, etc. Then yesterday when I change my engine oil, I poke around the engine bay, and found that there are some movement if I press on the red engine cover (left side when facing the engine). The 2 bolts there are tightly screwed in, BUT they do not press down agains the cover firmly.

This is the uh-ha moment for me. I took out the 2 bolts, wrapped some electrical tap on the smooth portion of the bolt, then put them back in. Now the cover is firmly pressed against the engine, and no movement at all. If you have the right size washers, they should work too.

After a day's of test drive, I can confirm that the buzzing noise is gone! Now I can enjoy the car again (minus a bunch of cabin noises that I'll tackle separately).

Sponsored

 

[ABPDE5]

"Always change gears below 3k rpm"

 

[optronix]

Very similar experience with the dealer, although mine was focused on the "wastegate rattle". First of all, I have some operational empathy because I worked at a dealer, in service, in what feels like a past life at this point. I know it is hard, and frustrating, to diagnose noises. Any such complaint would illicit rolled eyes and groans from techs just from reading the description of the issue- universally. So I understand that part.

But ultimately these dealer mechanics HAVE A JOB TO DO. They have to take these complaints seriously, and more importantly they have to have the capacity to diagnose and RESOLVE the complaint effectively.

And the vast majority flat out DO NOT have this capability. "Master tech" designation or no.

What ended up happening with mine was almost the same story, except they had my car for several days, over multiple trips. A miserable experience overall but the real kicker came in the next few weeks as I discovered multiple NET NEW rattles and buzzes, and the traction control button left unplugged. I had to remove a panel under the steering column to plug it back in, and found several broken or missing clips. Explains the new rattles...

Eventually my plan is to just fix all this myself by just ordering a shitload of new clips. I've considered bringing the car back one more time to give them one last opportunity to actually fix it - and going scorched earth if they don't- but I just do not trust the dealer at all at this point, and will ONLY use them explicitly for warranty/recall work.

 

[ChromaPop]

I would have gone scorched earth on the "keep it under $3,000 RPM statement", absolutely ridiculous. Thanks for sharing the solution to something we may incur.

 

[UWU-mancer]

I would have gone scorched earth on the "keep it under $3,000 RPM statement", absolutely ridiculous. Thanks for sharing the solution to something we may incur.

I don’t think anyone would’ve blamed you. Ludicrous response from the dealer

 

[Frenzal]

On a cold engine, you should keep low RPM until the engine is fully warmed!

But after warmup, no problem going to redline!

 

[3rdcoast]

Keeping the RPM under 3,000 until warmed up is just smart. Both the life of the engine and turbo will thank you. Cold startup and operation is the hardest operating condition on components. With the oil being thicker at startup it can compromise lubrication, starve bearings and increasing wear. It doesn't take a long time for these engines to warm up so why risk unnecessary damage? My opinion as an aerospace engineer that worked with challenging lubrication conditions for years.

 

[UWU-mancer]

I keep my shifts to 3k and under when the engines cold. But as soon as the radiator/water temp gauge shows me that fourth dash mark. I start shifting as high as 4k rpm but I stay far from boost

I’ve no way to monitor oil temps. So I typically wait about 10-15 minutes after I get that 4th dash mark on the radiator water temp gauge.

 

[itsgr8]

Keeping the RPM under 3,000 until warmed up is just smart. Both the life of the engine and turbo will thank you. Cold startup and operation is the hardest operating condition on components. With the oil being thicker at startup it can compromise lubrication, starve bearings and increasing wear. It doesn't take a long time for these engines to warm up so why risk unnecessary damage? My opinion as an aerospace engineer that worked with challenging lubrication conditions for years.

Fully agree not driving the car aggressively while cold. Problem is:

- there is a merge to a main road (cars driving 60+ mph) right out of the parking lot where I worked, so I often just have to accelerate with a cold engine
- "driving under 3K RPM" was the dealer's "solution" to my buzzing noise complaint - that's not acceptable.
- The buzzing noise usually lingers a lot longer even after the car is up to temp (4 bars)
- The noise indeed was because of the loose engine cover, not because of high RPM when cold.

In retrospect, I think the reason why the buzzing noise eventually disappeared is because the bolts expand a bit when heated up and fill in the gap, thus holding the engine cover better when the car is fully-fully warmed up.

 

[itsgr8]

On a cold engine, you should keep low RPM until the engine is fully warmed!

But after warmup, no problem going to redline!

see my response above. If I had a choice, I'd keep the engine at low RPM when cold.. just that sometimes I needed to merge to a high speed road with a cold engine.

 

[itsgr8]

Very similar experience with the dealer, although mine was focused on the "wastegate rattle". First of all, I have some operational empathy because I worked at a dealer, in service, in what feels like a past life at this point. I know it is hard, and frustrating, to diagnose noises. Any such complaint would illicit rolled eyes and groans from techs just from reading the description of the issue- universally. So I understand that part.

But ultimately these dealer mechanics HAVE A JOB TO DO. They have to take these complaints seriously, and more importantly they have to have the capacity to diagnose and RESOLVE the complaint effectively.

And the vast majority flat out DO NOT have this capability. "Master tech" designation or no.

What ended up happening with mine was almost the same story, except they had my car for several days, over multiple trips. A miserable experience overall but the real kicker came in the next few weeks as I discovered multiple NET NEW rattles and buzzes, and the traction control button left unplugged. I had to remove a panel under the steering column to plug it back in, and found several broken or missing clips. Explains the new rattles...

Eventually my plan is to just fix all this myself by just ordering a shitload of new clips. I've considered bringing the car back one more time to give them one last opportunity to actually fix it - and going scorched earth if they don't- but I just do not trust the dealer at all at this point, and will ONLY use them explicitly for warranty/recall work.

Thanks for sharing your experience. I now have also lost faith to the dealers and probably will only go there for warranty or recall as well.

 

[justa335i]

Eventually my plan is to just fix all this myself by just ordering a shitload of new clips. I've considered bringing the car back one more time to give them one last opportunity to actually fix it - and going scorched earth if they don't- but I just do not trust the dealer at all at this point, and will ONLY use them explicitly for warranty/recall work.

I feel you. I went to my Acura dealership for an oil change and they forgot to tighten my drain bolt. Found this little gift later that day when i went to take out the car again. It scares me that something so basic can be missed, which could have caused engine failure. The bolt wasn't even "hand tight", just threaded ~3/4 of the way on. The dealership is also 45 mins from my house, so im happy it didnt fully back out.

Sponsored