[Tech] Rattling sound during acceleration.

[Raven52]

I have a 2005 Mazda 3i with a manual transmission. I have noticed a slight rattling noise underneath of the car during the first second of acceleration for the last day or so. Maybe it has always been there and I can only hear it bad when I have the window down or the music turned off. It sounds like it is right underneath the driver seat.

I have a couple of thoughts on this but don't know if any of them are valid.

First I have noticed that the engine as a whole is a little louder until the car is completely warmed up. This seems to be typical of all Mazda's though. My 626 and RX-7 both had this issue and they were both manual transmissions. Once the car warms up, that noise goes away. Plus almost all of the excessive exhaust noise is during first gear driving. It is really noticable when I am in a drive through line. The car usually never leaves first gear once I get in the line to order.

Secondly, the only time I have heard this type of rattle was when my catalytic converter went bad in my 626. When I would accerlerate, I would hear this metal rattle underneath of the car. When the mechanic removed the converter he shook it to show me how it was making the noise. But can a catalytic converter already be bad with a car that has 250 miles on it? When this happened in my 626, the car was about 13 years old and the loud rattle was a constant noise while driving. This rattle only happens on the initial gas burst and it lasts about a second before smoothing out.

Third, I could be just losing my mind over something that means nothing!
Like I said, it only makes the noise on the first initial burst of the gas pedal. Is this just how the car sounds?

Has anyone noticed if their "3" is just a noisier car?

I know that in Consumer Reports, the one complaint about the car was that it had some excessive noise whether it was from wind or engine.

I could take it to the dealer but I don't want to look like an idiot and no service lights are popping on either. If I still hear it by the time of my first oil change, I'll have service check it out.

Hopefully someone can verify that their "3" makes a little more exhaust noise than maybe a Honda or Toyota. I was driving a 2003 Civic Coupe (automatic) before I purchased my 2005 Mazda "3i". Maybe Hondas are just more quiet? But I can tell you that a Honda is not as fun as a 3!

Or are manual transmissions just louder than automatics?

[millyowner]

The flex section on the exhaust may have taken an impact and is leaking slightly when engine torque shifts its position. A small leak can sometimes be perceived as a mechanical rattling sound...especially under load.

Otherwise, the sound could be clutch related. Do you abuse the clutch? I've been a passenger with people who own and drive a manual on an everyday basis and unknowingly destroy their clutches (although this is probably not your case )

[Raven52]

Originally posted by MillyOwner@Dec 3 2004, 05:31 AM
The flex section on the exhaust may have taken an impact and is leaking slightly when engine torque shifts its position.* A small leak can sometimes be perceived as a mechanical rattling sound...especially under load.

Otherwise, the sound could be clutch related.* Do you abuse the clutch?* I've been a passenger with people who own and drive a manual on an everyday basis and unknowingly destroy their clutches (although this is probably not your case* )

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Well, I can say that its definatley not my driving. I only have about 250 miles on the car and I shift a smooth transition at 3500 RPM's. Now before everyone starts calling me a wuss , I am just following the golden rule of the first 600 miles for a cars life. Don't overdo it!

I know what you are saying though about abusive manual drivers. There are some people I know that could drop a transmission on the day the car is built!

It definatley sounds like a leaky exhaust pipe though. So hopefully that is the problem. It doesnt affect the ride at all, I just notice it every once in a while if I drive with no radio. I'll probably have the dealer check it out when I go in for my first oil change. It just makes me feel a little better that some one else thinks its an exhaust problem as well.

[harobiker]

Originally posted by Raven52@Dec 3 2004, 08:32 AM
Well, I can say that its definatley not my driving.* I only have about 250 miles on the car and I shift a smooth transition at 3500 RPM's.* Now before everyone starts calling me a wuss , I am just following the golden rule of the first 600 miles for a cars life.* Don't overdo it!*

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Not a wuss. A smart car owner. Those that think slamming through the gears every 6500 RPMs makes you cool are rediculous. And some people wonder why their car starts doing bad things at 60,000 miles or so.

[Raven52]

Originally posted by harobiker@Dec 3 2004, 01:56 PM
Not a wuss.* A smart car owner.* Those that think slamming through the gears every 6500 RPMs makes you cool are rediculous.* And some people wonder why their car starts doing bad things at 60,000 miles or so.

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Well, after further review, I guess I am just imagining things. I keep forgetting that for starters and manual transmission is going to be a little noiser than an automatic. Plus I am going from a 116hp SOHC to a 148hp DOHC. Of course its going to be a little louder. Also it seems that I am bogging down a little on first gear and that low rattle is almost 100% attributed to that. I had never owned a new clutch (all used ones before) plus I have been driving an automatic for the last year.

Well, off to the Ravens game! Ahhhhh, there is nothing like popping open that first beer at 9:00 A.M.!!! Tailgating is awesome!

[crossbow]

Does the rattle only occur at certain rpms? If so, it could be a bad idle tensioner pulley. (It would come from the passenger side of the engine). This issue has cropped up on a number of cars, 6 and 3.

Btw make sure to vary your rpm's through the entire rev range. Its just as bad to keep a car under a certain rpm then to go balls wild and rev the **** out of it during the first 600 miles.

Gotta make sure to stretch the engine out, which requires going through the entire rev range "once in awhile" under the 600 mile marker.

Best analogy? Go to a gym, see all the guys with the giant chests and tiny legs? They didn't rev through the entire rpm range.

[Raven52]

Originally posted by crossbow@Dec 9 2004, 09:55 AM
Does the rattle only occur at certain rpms?* If so, it could be a bad idle tensioner pulley.* (It would come from the passenger side of the engine).* This issue has cropped up on a number of cars, 6 and 3.

Btw make sure to vary your rpm's through the entire rev range.* Its just as bad to keep a car under a certain rpm then to go balls wild and rev the **** out of it during the first 600 miles.

Gotta make sure to stretch the engine out, which requires going through the entire rev range "once in awhile" under the 600 mile marker.

Best analogy?* Go to a gym, see all the guys with the giant chests and tiny legs?* They didn't rev through the entire rpm range.

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After further examination I figured it was really nothing to worry about. The sound is actually coming from the muffler during the initial takeoff in first gear. I am just not used to a system that makes a little more noise. I used to drive an automatic 2003 Honda Civic Coupe with a SOHC 116hp engine and a tiny little exhaust pipe.

Now I am driving a manual DOHC 148 hp engine with a muffler twice the size of the Honda. The rattle was just a little more exhaust noise when I would start in first gear. It happens when I technically "bog" the engine because I am still getting used to the gas to clutch ratio with this car.

By the way, I owned 2 manual transmission cars before my Honda. I had a 1986 626 with a 5 speed (this car was a tank), and a manual 1987 RX-7. So I am not a noob at this, I just have to get back into the groove again. Plus the 3 is much faster than the Honda. Also because of driving the weak ass Civic, I have aquired quite a leadfoot. I have to learn to back off a little when driving my 3. I don't need much to get this car movin!

When I get the transfer just right, I don't hear the low rumble from the exhaust pipe. Either way, I take the car in January for an oil change. I will have the tech take a look at it just to make sure but everyone who has driven in the car with me hasn't noticed anything out of the ordinary. The 3 is just a little louder.

[crossbow]

Ah ok. Cause a light rattle at lower rpm's (windows down to usually hear it) occurs for a brief second as the idle tensioner pulley rattles. Best heard from the passenger.

You could have a loose or missing exhaust bushing, which would make the exhaust rattle a bit at certain rpm's. Thats an easy fix though, just gotta get some exhaust bushings from kartboy, or have the dealer replace it.

But if you think its a normal sound, then it is...but due realize that most friends/family members won't notice that type of stuff, cause they aren't nearly as in-tune with the car as much as you are...you drive it all the time, I doubt they're always in the car with you .

[Raven52]

Originally posted by crossbow@Dec 9 2004, 11:15 AM
Ah ok.* Cause a light rattle at lower rpm's (windows down to usually hear it) occurs for a brief second as the idle tensioner pulley rattles.* Best heard from the passenger.

You could have a loose or missing exhaust bushing, which would make the exhaust rattle a bit at certain rpm's.* Thats an easy fix though, just gotta get some exhaust bushings from kartboy, or have the dealer replace it.

But if you think its a normal sound, then it is...but due realize that most friends/family members won't notice that type of stuff, cause they aren't nearly as in-tune with the car as much as you are...you drive it all the time, I doubt they're always in the car with you .

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Thanks for all of the advice!

I can tell you though that I don't think that the tensioner pulley would be the problem. The noise is definatley coming from the exhaust pipe which runs directly under the driver side. There is zero noise coming from the passanger size.

The exhaust brusing makes me quite curious though. I may go ahead and check that out. But I really think that it is just some normal exhaust noise when I lightly bog the engine in first gear. Like I said when I get the transfer right, it's sound just fine. I think its more driver error than anything.

Like I said though, thanks for all of the help! This is why I come to the forums!

[Axendoman]

Does the rattle only occur at certain rpms? If so, it could be a bad idle tensioner pulley. (It would come from the passenger side of the engine). This issue has cropped up on a number of cars, 6 and 3.

Btw make sure to vary your rpm's through the entire rev range. Its just as bad to keep a car under a certain rpm then to go balls wild and rev the **** out of it during the first 600 miles.

Gotta make sure to stretch the engine out, which requires going through the entire rev range "once in awhile" under the 600 mile marker.

Best analogy? Go to a gym, see all the guys with the giant chests and tiny legs? They didn't rev through the entire rpm range.
[/b]

Hi folks,

I'm new to the forum, but I have a question related to a comment made by Crossbow. Crossbow mentions the issue of bad idle tensioner pulleys has popped up on a number of cars. I have a 2004 Mazda 3 GT Sport and my pulley just failed on the Easter weekend. The car as 73500kms on it (all highway). It seemed weird to me to have such a failure, let alone at that mileage. Does anybody know more details about this problem. The dealer told me nothing other than it was not under warranty! I'm beyond my bumper to bumper warranty (60000km). Any info would be appreciated.

Thanks.