Knocking Sound as Car Rocks Back and Forth, Motor Mount Maybe, IDK?

2005 Camry. I noticed a bit of shaking of the steering wheel while driving, who knows maybe it is normal, I’ve also notice what in my opinion was excessive bouncing up and down while going over pumps, but last time I bleed my breaks I didn’t notice any leaking fluid from the struts. While driving earlier today I heard a knocking sound, almost as if something was rocking back and forth. I heard it while driving straight, turning, up a hill, pretty much all the time, even on smooth pavement without bumps. When I got out of my car I rocked my car back and forth, forward and back (not side to side) and heard the noise. I thought it was coming from the tire area. I opened up the hood and rocked the car back and forth. I had what I thought was excessive engine movement while I rocked my car. I had what I thought was excessive movement of the upper mount here.

I was able to time up the peaks of the oscillation with the knocking sound. Meaning as the engine rocked back and forth, before it started rocking in the other direction I heard the knocking sound. So it seemed to have to do with the engine rocking back and forth, or perhaps some other item that was also oscillation at the same frequency. I checked the torque mount, and I didn’t see any cracks etc in it. It looked fine to me. Here’s a video of the sound with the car off. The amount of movement back and forth isn’t as drastic as I noticed earlier today. I checked the hydraulic mount near the transmission, and didn’t’ notice excessive movement. So I think it’s probably the torque one, or it could be entirely something different. What do you think the source of the knocking sound could be?

Thanks for any help?

If the wheel is shaking when you are driving… and you are not using the brakes…then you have an issue with one of your front tires. If the wheel shakes when you travel at very low speeds it will be something like a belt inside one of the front tires letting go internally…which makes the tire out of round.

If the wheel shakes more at higher velocities then it will be wheel balancing.

If the steering wheel shakes when you apply the brakes lightly at say 60mph or so…it will be the brake rotors.

I’ve solved many of these issues over time as they are common. My Exploder had a front tire that looked outwardly healthy…but as I traveled the steering wheel would rock left n right it would also gently rock the entire vehicle… SO… I hung my head out the window to watch the tires turn as I drove slowly…and sure enuf… I could see the tire defect as it rolled…that day it was the drivers side…but I did also hang out the passenger side as well with a friend driving. Sometimes it takes measures like this to fix things. I had to scrap that tire…it had about 50% life left but…I could clearly see some out of round defect caused by some internal failure within the tire… Its common.

I applaud your troubleshooting… You may make a fine Shade Tree Mechanic one day. As far as the motor mounts go? They are there to hold the engine and isolate vibes…they do their jobs well but you will see quite a bit of engine movement when the car is off and you are pushing on the bumper forward n back…some movement is normal…excessive is not. To take your motor mount troubleshooting one step further… Open the hood… Put the car in drive…hold the brake on hard…and push the accel on and off… you will witness the flex in the mounts… then put it in reverse and do the same…Then…go from Drive…to Reverse…with an accel push in each gear (the accel is to be applied only when in gear…not in between gears) to see the full swing of motor mount flex.

Most people only see and replace the uppermost motor mount…leaving the other two alone…this is a mistake… The others dont fail too often…but if the mounts were ever contaminated with motor oil…they degrade much much faster as the rubber in the mount basically tries to turn back into oil…because of the contaminants.

Its probably the lower control arm bushing because the knocking noise is typical. I had to replace both bushings on my Corolla.Anytime you hear a knock like this,think about deteriorated bushings that make metal to metal contact.

As far as your noise while you were rocking the car? My take is that it is the slack you are taking up in the transmission and CV joints…because you are loading and unloading the axles and trans fully forward and then backward. There is a bit of play between the trans and axles… I think you are just hearing the slack involved and its perfectly normal… up to a point of course. I didn’t see or hear anything excessive from my computer desk.

If you hear clicking when you turn the wheel and apply power…it is a cv joint going bad… usually due to a split boot that is allowing the grease to escape…cv joints dont last long without grease.

But otherwise that noise I heard just sounds like the normal play in the drive train. If you poke around long enough and are prone to hypochondria you can drive yourself semi insane listening to the sounds your car makes when you are poking at it and rocking it back n forth… lol… so, dont go nuts with it.

I suspect that those two things have already happened to John Smith .

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You bucking for some flagging again @VOLVO_V70 ? LOL…

I just had two posts flagged IN ONE DAY… I’m on a streak man!

You must have been drunk when you made that video.


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I had to turn it off because it was giving me motion sickness!

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Sorry I was trying to shake the car while filming, and to throw my body into it to get it to rock.

It’s good to hear that it may not be an issue. I’m thinking though if I can heart it while driving at low speeds it might be a problem? I’ll see if I can replicate the excessive movement I saw yesterday. It scared me how much movement I saw.

I’ll see if I can get the tires off in the front and shake the lower control arm and see if I can replicate the noise to see if that might be the issue. I also have other tires I can put on as well, but I’m not sure if that will help. I probably won’t have time until the school semester is over though.

Yea sorry, I’m not as familiar with what’s normal and what’s not normal, so it’s all just guessing, then having to ask others with more experience if it is or isn’t normal.

So I was able to replicate the knocking sound while driving at low speeds, but not the excessive rocking motion. I have some time later today, and I’ll probably check with the wheel off. You guys think that this might be my lower control arm, and I test this out by moving it up and down with the wheel off. You can hear the sound in the video below.

I did do my front breaks recently, but I’m not so sure if this might be what I’m hearing?

Brakes should be next.


Thanks, yes brakes,

So I got the tire off and noticed that I can create a knocking sound by rotating the tire studs, it causes a knocking sound when it hits the rotors. I noticed some knocking sound when moving what I believe to be the tie rod? Does this help at all in identifying the source of the sound, I didn’t have this much wiggle room with the rotor and studs on the other side of my vehicle. Please let me know. Thanks.

The rotor has clearance holes for the wheel studs. When the wheel is removed and you try and rotate stuff you can create noises which can be misleading. You can move the cv axle in/out as there is a tiny bit of slop in cv joint. This can give you the impression the axle is making noise. When it is not.

This is very interesting. Thanks so much for the help. What do you think the source of the sound is? In post 10 is a video of me recording the noise while driving, it can be heard while driving, a constant knocking sound.

The other wheel in the front of the car was similar to the one in the video in post 12, no knocking sounds could be created other than the ones that can be heard in post 12 from the same parts.

Remove the wheel covers and see if that noise goes away.

Unfortunately these types of questions…unless the issue is very obvious… will never be able to be answered via a forum like this. Its situations like these when you need someone who knows what they are doing and hearing regarding vehicles. The slightest change in angle or nuance can throw a sound and us, completely off and make any guesses seem silly.

You really need boots on the ground to diagnose things like this accurately. One of the many drawbacks of an internet forum.

I and many others have found and solved problems by smell…another thing we cannot do. People asking us about funny problems or sounds they are hearing all while ignoring and omitting the mention of the smell of burning brakes for instance… Leaving us… in the dark.

If I were you… and actually worried… I’d ask a real person… really and in person.


So I believe I found the source of this knocking sound. I got the rear of the car up in the air, and spin the tire, and I hear the knocking sound! I take the wheel off and spin the drum, and still hear the knocking sound. I take the drum off and spin the wheel hub, and do not hear the knocking sound. I still hear this sound now that I have new break shoes, new tire, and a new drum that all needed to be replaced regardless.

It seems that this part of my car, see the blue x, is rusted pretty badly, with sheets of rust on the inside part. I would like to test this theory out. What exactly is the name of this part? Maybe I can try and replace it and see if the noise goes away. So I hear the knocking/grinding sound when I rotate the drum 360 degrees. Meaning that there seems to be a single spot that is causing the sound when the drum rotates.

Searching for Brake parts is a lot easier if you actually spell brake correctly.

Sorry. What is the name of this brake part?

It’s the dust shield for the rear brakes.