Rattling under car

I have a 2001 Honda Civic LX sedan. For over a year now there is a rattling noise and vibration coming from underneath the front of the car when ever the car speed is below 40 mph. I’ve taken it to several mechanics, who have driven it, heard it, but have no idea what it is. I’ve invested almost $400 into replacing the bushings, lower control arm, and even had the transmission rebuilt. Any idea what could be causing this rattle? Please Help.

Very frustrated,

Paul Janssen

From what I’ve been researching online, people are saying it could be:

Exhaust Pipe / Heat Shield Around Exhaust Pipe
Exhaust shield or Wheel Rotor shield
Motor Mount / Motor Mount Bushing ***
CV Joints

I’ve dumped so much money into this already, I need to know exactly what it is.

Well for one wild guess, I would bet it is a heat sheild over the exhaust pipe or muffler.

I would also guess that it’s the heat shield around the catalytic convertor is rattling.

Okay, quite a few people, both on here and elsewhere have mentioned “heat shield.” First, thank you so much for your input. Second, I really don’t know much about cars, are there “two” heat shields? One over the exhaust pipe and one around the catalytic converter?

Thanks again!

Also… wouldn’t it rattle all the time instead of just during acceleration? Maybe it does and I just don’t hear it, but I it seems to stop whenever I take my foot off the gas.

If it is a heat shield it rattles at different times depending on how much exhaust is going into the system and vibration(s) transmitted via the motor. It tends to be “harmonic” and kicks in and out at certain times.

This is pretty common and your mechanics need to put their “dunce” caps on if indeed it is a heat shield and they missed it.

No kidding. Or at least refund me or give me my next few visits “free”. We’ll see when I take it to them. They suggested I take it back down to the guy who rebuilt my transmission to see, first, what he thinks or if he missed anything. My guess is, he didn’t because my transmission is running fine.

You know, after I got on YouTube and listened to the sound of rattling heat shields, they are very “tiny, clunky and metallic” sounding. The sound that my car makes is a very low “vibrating-rattle” sound. You can almost feel the something under the car shaking. The problem is more persistent when making slight right turns or veering to the right on or off an on ramp.

They’ve checked the tie-rods and struts. The guy said there is no oil leaking from the struts so he doesn’t think it’s the struts.

I don’t know if this helps, but the first time we noticed it, it literally felt like a wheel was going to come right off and roll out from under the car. Now, we’ve been told over and over that will not happen. But I’m nervous, because it’s my wifes car and she is pregnant with our first. So, I’m being a little overly-cautious and I’m very frustrated that no one can seem to find the problem.

Could it be a bad motor mount?

a bit out of the box suggestion but if you drive on gravel check brake rotors for rocks.

Have you had your wheel bearings checked?
A noise that changes, depending upon which way the steering wheel is turned while you drive, is suggestive of a wheel bearing problem.

Also–I really hope that there was some valid reason for your transmission to be rebuilt.
If a mechanic told you that your transmission needed to be rebuilt because of a rattling noise underneath the car, and if no other symptoms existed, then that mechanic should be AVOIDED at all costs in the future.


Thanks for your reply. The problem with the transmission was a separate issue. The car kept stalling at stop signs and traffic lights. The first mechanic I went to said he doesn’t work with transmissions but recommended I go to a transmission specialist. I found a reliable one from a friend, and he found that something in the transmission was spewing shards of metal all over causing my car to sputter out while stopped.

This was at the same time of the vibration noise under the front of the car. Are the two related? I don’t know. I took the car out yesterday with a video camera. I’m trying to capture the noise on video. I realized that it takes the car a little while to start doing it. It seems to do it after the car has warmed up and been driven for about 10-15 minutes. I hope to have a link to YouTube with the actual noise very soon. I will post the link here in this forum. Thank you for all your help.


Thanks for your suggestion. I will def have that checked out. No idea is a bad is a bad idea to me. I just want to figure out what this is… it’s been over a year.

Can you maybe isolate the area and describe a bit better the sound for us? The front is pretty wide open and rattling is a bit wide as well. I’ve just gone over the suspension for my '89 Accord and our '95 Civic and did so due to noises which bothered me. Suspension issues are nothing to fool around with . . . a safety issue for certain. I might be better able to help you if you could isolate and describe a bit better. Rocketman

The vibration sound comes from under the front of the car, passenger side. It sounds like it comes from near the wheel. Our mechanic has looked and looked a the wheels and has assured us it’s not anything with wheel. He’s replaced the sway bar, bushings and lower control arm. None of these things have worked. Our mechanic’s dad (family business) thinks it’s the struts. His son doesn’t think so. Can you understand my frustration? Every time I take it there I end up spending more money on the same problem that I’ve already paid three times to have fixed.

Maybe it is time to sneak out to another city for a second opinion, and repair if necessary, or at least a proper diagnosis so you can put on your thinking cap and say hmmm, would you mind checking… if you get it fixed and they ask just tell them oh that noise went away, everyone will be happy.


Thanks for your reply. The problem I have is that I’m not made of money. I’ve invested almost $400 into just this problem with this current mechanic. They owe me a fix. I do agree with you on getting another opinion. The problem there, again, is that I’ll be charged for anyone else to inspect it. I should have taken the car to a Honda dealer to begin with. Yes, I would have paid more up front, but they probably would have found the problem right away and fixed it. Yes it would have cost more, but I’m probably going to end up paying more anyway. Know what I mean?

Again, let me try and give you all the symptoms of the problem.

A low-sounding, vibration or knocking sound coming from under the front (maybe passenger) side of my 2001 Honda Civic LX. The sound only happens at speeds of 10-45 MPH and only while accelerating. The second I take my foot off the gas, the sound stops. Our mechanic has replaced the sway bar, bushings and lower control arm. He does not think the struts need replaced because they are not leaking oil. I’ve listened to the sounds of a bad “heat shield” on YouTube. Those sounds are high, tiny, clanky, and metallic-sounding. This is a low-vibrating-knocking sound. You can feel something vibrating under you feet when you hear it.

The only other person who seems to of had a similar problem is this guy. His solution, sell the car. I’ve invested too much to do that. Plus, the car is paid off.

I really, really appreciate all of your advice and thoughts. If my replies sound frustrated, I do apologize, it’s just that I am very frustrated. This is Honda. It only has 147,000 miles on it. I should be able to get 100,000 on it.

With this more complete explanation, I am beginning to wonder if the engine is exhibiting spark knock, also known as “pinging”. Are you familiar with that sound? To many people, it sounds like pebbles ratting around in a tin can. This might be one more possibility to explore.

This problem can be caused by poor maintenance, an engine that is running too hot, and a gunked-up EGR valve, to name the major possibilities.


Thanks for your reply. I will look into that. However, it seems to me that the sound of “pebbles rattling around in a tin can” would be rather distinguishable. A high and tiny sound is not what this sounds like. I wish I could find a way to record the sound. The only way I can describe it is a “low” vibrating sound that sounds as though it’s coming from beneath the front the car or the passenger wheel. It also seems to vibrate the steering wheel a little whenever the sound is heard.

Thanks so much again for your interest and thoughts. I really do appreciate them.