Rattling sound coming from exhaust under 2000rpm when accelerating (not in 1st gear)

[newprot5fan]

Hey all, got a question for you...

I have a rattling coming from my exhaust (at least sounds like it is comign from my exhaust) when I try and accelerate if I am under 2k rpm.....Is this detonation? I have NGK long reach plugs in my car. I have no noise coming from the engine bay when this happens (no marbles in a can noise up front) but it sounds like something rattling in the exhaust in the back.....


Thoughts?

Thanks

 

[Purrfectangel]

chances are if you lost your heat shield because it rusted loose, something else is likely loose from rust underneath making the rattle you hear. No it's not a safety issue. You do not require it to pass inspection or anything. I don't have that heat shield on anymore, don't even have the front one on. I did strap it up twice but when my midpipe seal let go I junked it. It's just there to help protect your exhaust if you bottom out and to protect other parts from excess heat.

The rattle you hear might be what's left of the bolts that was holding your shield on or a loose hanger. I don't think it's anything serious. Jack it up on the passenger side and take some pics. We might be able to help you out a little more or take it in and have it looked at. But just get them to look and not fix. Where it's an older model car most of the time it's not worth have the dealership fix it, if it is anything serious. But I don't think it is.

 

[ProtoType5]

I have a rattling coming from my exhaust (at least sounds like it is comign from my exhaust) when I try and accelerate if I am under 2k rpm.....Is this detonation? but it sounds like something rattling in the exhaust in the back.....
Thoughts?
Thanks

Didn't you just post that a heat shield fell off your exhaust....It's probably rusting out and will need to be replaced...Its easy to find the rattles once you get under the car and look...

 

[major error]

+1 on the heat-shield check.

Most of them are only attached in a couple places, and when any one of those welds rust through, rattling is a result.
If the shield is still partially attached, a couple stainless "strip clamps" will take care of it.
(had this happen on both cat heat shields on my old truck.)

 

[newprot5fan]

+1 on the heat-shield check.

Most of them are only attached in a couple places, and when any one of those welds rust through, rattling is a result.
If the shield is still partially attached, a couple stainless "strip clamps" will take care of it.
(had this happen on both cat heat shields on my old truck.)

Thanks for the responses...

That noise could be screws rattling but it jsut has a different sound that I don't think I could attribute to rattling screws. A couple of people said that detonation can sometimes sound like rattling coming from your exhaust, so since I have those long reach plugs in, maybe it could have been that....weird that I hear nothing in the front of the car though.

 

[Markmitsu]

Could be your CAT, same with mine it rattles just under 2kRPM

 

[MTV]

Could be detonation. Slap some 89 octane in there. Mine went away after I put a higher grade fuel in it...

 

[brickisred]

I had a similar rattle (I was worried that it was detonation) in my Nissan truck. Turned out that a small rock had found it's way in between the muffler and heat shield and would rattle when I accelerated. I took the heat shield partially off and found it, but broke a bolt head while doing so. Exhaust parts can get very corroded...

 

[zaggu]

well, I am getting that rattling when cruising at 2000rpm. I drive protege 99. Dealer, Autopro, Midas and another 4th mechanic have had looked at it one after other in last 8 months. Midas slapped me with exhaust pipe replace saying that its the CAT. For sure its still not resolved. When engine is not running and I rock the car it makes like dry metal squeezing noise. You hear the noise only and only from exhaust pipe/muffler areas. I am simply going nuts by this problem. Heat shield, all seem ok. Recently, when turning the A/C on, when on drive gear and idle, it makes 'almost' same noise. If in parking gear, turning the wheel about a half to left or right, the rpm goes a bit up and there is the noise.

 

[mx-p5]

I had a rattling exactly where you describe. Turned out to be the exhaust rattling against heatshield.

 

[thrasher]

I also have a rattle on acceleration, but not in the morning when the engine is cold. I have shaken my exhaust and can not get anything to make a sound. Only when I accellerate.

I was convinced it was some sort of detonation, so I swapped out my long reach plugs, still rattled.

I changed my timing belt (a 6 hour adventure by myself), and it still rattles.

It sounds like it could be a screw in the exhaust somewhere. I suppose.

I'm gonna put in some 94 octane this weekend to try and rule out detonation. Taking exhaust pieces apart usually breaks things due to corrosion so I don't want to do that unless I have to.

I also have a gutted pre-cat, so in all likelyhood there may be something rattling in the cat or the muffler.

 

[mx-p5]

Have you checked the heat shield just above the resonator yet?

 

[thrasher]

Hmm, no I haven't. The one at the J-bend has rusted off long ago. I'll have another look under there today.

 

[mx-p5]

The one that is more than likely causing problems is the one directly below the shifter.

If you get under the car, there is a heatshield ABOVE the exhaust. That is more than likely where you're getting your rattle from.

If possible, get someone to rev while you're listening below to get a better iea where it is coming from

 

[thrasher]

But that's half the problem, it only rattles under load.

Which leads me to think that you are right. Under load with bad mounts, the engine will shift, the exhaust will shift, and it most certainly could be touching a shield. Maybe there isn't even anything loose and that's why I have had difficulty finding the rattle.

I'll check clearances.

 

[mx-p5]

Do you have the stock shifter? Or TWM? I installed the TWM which included spacers to drop the heatshield and that's when I got my rattle. I got under the car with a rubber mallet and beat on the shield a little so it bend up some, but not enough to come into contact with the shifter

And if you have bad mounts, start the car, pop the hood, and rev the car. You'll be shocked at how much the motor will bounce around with bad mounts!

 

[thrasher]

oh ya, my mounts are bad. I took the AWR out, couldn't stand them. And then the same for the sls. back to a worn out oem front.... but without the vibrations.