Intermittent knocking sound outside--behind gas/brake pedals

My car (Corolla 1997; 95K miles) makes an intermittent no rhythm pattern slow knocking noise which appears to come from underneath the accelerator and gas pedals. It sounds like a “door knock” from the floor behind the pedals. Alhough I hear it only when the car is moving, it does not seem sensitive to speed nor to turns. Making sharp turns any direction does not make a difference in the noise. It may be sensitive to temperature of the engine or surroundings (I don’t hear it early in the morning when the outside and engine temperature is cold.) The noise is not regular–sometimes its there, sometimes its not. When it comes out, it is usually when the car is being been driven for about 30 to 45 minutes city/suburban driving. Once it starts, it stays there and disappears only after the car has “rested” overnight or a few hours.

Thanks in advance for your help.

Does it seem sensitive to road irregularities or bumps? My best guess is sway bar links or possibly bushings for your lower control arms, crossmember, or steering rack. Engine or transmission mounts are also a distant possibility. Have you had the front end inspected?

The noise doesn’t seem sensitive to road irregularities. I actually had the underneath of the car checked. The mechanic said that it I need a new steering rack, ball joints and tie rods. Another technician at a place where they change oil and do wheel balacance/alignment said I would need new bearings on left side (that was before I started hearing the noise). But because it is an expensive procedure (over a $1000), I thought I would wait for the time when the noise becomes consistent and doesn’t go away. At that time, I plan to take it to the mechanic to let him listen to the noise I hear. Right now, I couldn’t make the noise appear at the auto shop.

Is it a safety issue?

Thanks again and would appreciate any views on this,

Can you post a sound clip when the noise is present?

The OP asked this question 9 years ago.

I wonder if they even still own the car?


Probably… NOT.

im experincing the exact same problem with my 2001 toyota celica. did you ever find out what was causing it?