Does anyone get a faint scratching noise from under the hood during mild acceleration? It sounds kind of like metal rubbing on metal. I usually notice it at low speeds, like around 2000 RPM in 2nd gear. Sometimes I also hear it when the engine is cold, and I shift into reverse with my foot still on the break. This is happening with the automatic transmission, 2005 model. I'm using 91 octane, and there is an appropriate amount of oil in the engine.

Thanks for your help,

James

 

I don't hear a scratching, but I do hear a hissing noise under mild acceleration. It comes and goes...I just assumed it was a natural part of a rotary's sound as it seems to be coming from the center of the car, where the engine is located.

 

I hear a noise under mild acceleration at low RPMs as well. It sounds more like a grinding noise, or a rattle, like a loose bearing. What is it?

 

Yeah, it does sound like a grinding noise more so than a scratching noise. I think we're hearing the same thing. Hopefully it's normal. Perhaps it's the transmission?

 

I thought it meant I was not feeding the squirrels enough...

 

I too hear that noise. I thought it was some kind of knock at first, but now I think it might be part of the intake system resonating or something related. I have just become convinced that it is the MO of this car. Hope I am correct

 

are there any previous threads about the exact same noise? It definitely sounds like something's loose. This is my second RX-8, and I've also had the similar noise in my first one, but it's more noticible on my current one. If it's just the MO of rx-8's, then I would worry. Anyone have any answers to this noise?

 

resonance from the intake system can make a noise like that? I know I've read that somewhere else before, but if sure sounds like a lot more than the intake to me.

 

hey, if theres any comfortin news, im having the same grindin noise under acceleration with me JDM too...

Its been there since i own it on OCT'03

Cheers... (hope its normal :D)

 

This just started happening with my car as well. It is more pronounced while on the highway, say at around 4K rpm and then when I go to accelerate, I get the "noise". It's a more subdued version of the knocking sound you would hear if you were running low ocatane gas, but light "grinding" is a good description.

Ths only change that I made that I can think of is cleaned and re-oiled my Green filter.

Would over-oiling the filter cause this problem?

I'm going to put the stock air filter back in and see what happens.

 

It's intake related somehow. The dealership has tried to figure it out a few times. They can't tell me what it is...just that it's normal. Half hour with the WDS..and I bet I could figure it out.

 

For what it's worth, I took my car into Mazda today to see if they could diagnose the sound. The tech said he had heard it before, and thinks it's a normal sound. I tend to believe him, because he described the sound to me before I described it to him. Good then. I'll stop worrying about this so much.

 

I hope it is not a seriou issue.... lubrication related. I have it too, more loud when it is cold outside. It started around 4000 miles. Same time with my car not taking 87 octane any longer (now I run 89 only).
The dealer's mechanic? "It's normal for the rotary engine" Which does not explain why it came at 4000 miles....
Any time they have no idea what is going on, they will claim is normal.... For example, see the pic for what happen to my air filter (maybe related to the noise here?!?) and I was told by Mazda.... "Some oil in the air intake is NORMAL." after the tech seen the filter !!!!!!!!!
Mazda probably re-wrote the meaning of "normal" in the dictinary since I last checked....
Moral of the story? If you got a strange noise, be on the watch for more strange things to follow.... and meanwhile, do bug those techs

 

This is a really old thread but its the only closest one that i can find about the noise I'm getting from the engine...
This is from a 07 mt with only 300 miles.
We just had a winter storm here in NC and it got pretty cold(not as cold as up north)

I always start the engine and wait till it warms up before I drive, and usually when temp gauge starts to move to operating temp I'd press on the pedal to about 3k rpm to get the car warmed up faster.
but since that cold morning the engine would hesitate at around 2k rpm making a scratching sound (or should I say a light scratching pulse) and it will almost stall or boggle unless I let go of the pedal or overcome it by pressing it harder, also the front end will shake alittle. The scratching sound is metal to metal and the speed of the sound pretty much reflects the engine rpm. (as rpm decreases from 2k to 1k the noise would slow down accordingly)

Idle is smooth even after it does this, and if I overcome the 2k hesitation it would stay smooth at 3k and above.
After the engine warms up, everything drives right with good amount of power, no hesitation anywhere in the rpm range driving and in neutral.
It'll go away for the rest of the day, but will come back the next morning
worried if its the apex seal and it tears my heart when I hear it. Is it just me? Am I doing something wrong? or is this not as bad as i think it is? oil is nice and full btw

thanks

 

I have the sound most people described here, it sounds like the valves on a diesel engine, the tech told me it's a flutter valve in the intake manifold that changes the geometry of the intake and that it's a normal sound.

take it to the dealership, you might have a problem with your oil metering pump? try running premix with synthetic 2-stroke oil (look at the sticky threads at the top of the tech forum) and see if it doesn't do it anymore before you take it in, if it goes away it might be the OMP. The warranty is your friend!

 

the filter looks normal to me. if you open the intake air filter box you'll see why all the dirt will center in the middle.

there are 2 walls right next to the bell shaped intake that keep air flow to the engine from only the area in the middle of air filter.

i actually took them out today (only held in with 1 screw each) and was surprised with a nice sound change. a lot more reverberation in the 3-5k range.

 

I have the same sound on my car.

 

With it being brand new don't hesitate and take it to a dealer.

 

Thanks for the replies, the sound hasn't come back in a while once the weather got better.

I read through the user manual and it tells me not to give gas when you cold start in a really cold day so I guess that was the problem, duh.

Im taking it to the dealer to get my speakers replaced (blown from day one) and I'll let them know about the noise, and maybe a oil change (@600miles).
I'm also getting a mini MIAC or a MIAC jr, beggining in the lower rpms but I guess thats another story...

 

does it sound like a diesel at the lower revs? like valve chatter? I have that sound to and when I took it in the guy at the dealership told me that it's the flutter valve in the intake and that it's a normal sound, I don't know if I trust him 100% on that so can you please update us on what they say about it?

 

I just heard the same sound few hours ago when I was about to go out...
I warmed up the 8 and accidentally hit the gas pedal when I heard this grinding/quirking/whatever noise (2-3k rpm) then I was like, wtf??! I opened my door to be able to hear it more clearly and yes it came from the engine. Then I revved up again after the temp needle started moving, smooth as silk but the sound came up again in around 7.5-8k (I was just curious) and the car was shaking.

After the car fully warmed up, it was all good.

FYI, it was kind of cold though approx. 3F there. I came up with this old thread and start to think that it's normal now.. any idea?

 

havent gone by the dealer yet, but I haven't had that problem since I don't give gas in cold starts, I'll wait about 2 min before I drive out slowly(even when I'm late fore work).
Although sometimes when I miss gears or almost stall the car uphill it'll make that squeeky scratching sound.

I have squeeky, scratchy, whistly, rattly, and marbles, all under my hood and they all come out in sequence.
Squeeky and scratchy comes out at the same time becuase they're good friends, rattly would comeout only in cold start idling, and whistly would come out and play at high rpms(proly the valves opening making some air whistle), and marbles hasn't matured enough to be really loud yet.

I don't really feel that they're serious problems, or any problem at all. You'll pretty much get the same noise from recipro engines, its just that being a rotary makes you feel paraniod in my case.

Ofcourse all these sounds that I'm getting are really hard to hear unless you go into a meditative state

 

yeah ive been hearing these crunching/rattling voices when i punch the gas pedal hard...im not sure wht this sound could be but it lasts for few seconds and then disappears...i have 04 AT ...any idea whts this sound may be i dont have a mazda dealership here in this country...

 

i get a weird rattle scratch noise when i'm close to redline i don't know wtf it is

 

My '04 6spd (75,000 miles) has also developed this sound. I noticed it after I had replaced my clutch line with a SS version, and adjusted the clutch pedal engagement point slightly. I thought the noise might be clutch related, since I can't seem to hear it when revving the engine with the clutch disengaged.

It has also gotten cold here around the same time, so I'll have to see if it lessens when the weather warms up.