Mechanics

WEIRD THUMP (FLAT TIRE SOUND) WHEN I ACCELERATE

2006 Toyota Corolla • 4 cylinder 2WD Automatic • 150,000 miles

I have been hearing a weird sound that resembles a flat tire (Thumping I guess?) Whenever I accelerate. This sound seems to be coming from the front left side of the car. If I let off the gas the sound goes away almost completely and I somewhat hear a roaring sound. If I put the car into Neutral and rev I dont hear anything, The same if im in Drive with my foot on the brake. When I idle the car is nice and quite no sounds. Whats weird is some days the thumping sound would be light, almost not noticeable. Other days its very loud and makes driving almost impossible. The sound would happen whenever Accelerating even if im turning, going straight, or on bumps. Theres no change other then how fast it happens according to speed.

I took my car to the shop and was told I was told nothing appears to be bad, Other then the front center motor mount (Which im replacing this week). I suspected the driver CV axle to be bad. I inspected it and seen no normal signs of being bad. I have replaced the driver side CV axle myself twice because it ripped and had a shop replace the wheel bearing, rotor, and pads. I have installed Koni inserts into the OEM struts and am lowered so perhaps this is a problem however I doubt it because I got a few friends who are lower then me and dont suffer this. I installed the springs and perhaps I didnt do it correctly?

I had a few people tell me the ball joints, tie rods, or even the CV might be bad. Although my guess would be either a bad install of the strut/springs, bad cv, and of course the motor mounts.
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Dave4989
May 9, 2011.



Engine mount could be one of the possible causes. The other that I can think of would be the CV inner joints. Check for excessive side play and signs of Cv grease splashed around the joint.

KHLow2008
May 9, 2011.
I took the car into a shop and was told the CV axle was fine. I personally inspected it and found no grease, tears, or anything abnormal. Although I did notice on the boot closest to the transmission on the bump (groves?) On the boot itself it's wearing out slightly faster on one area. The engine seems slanted the the driver side and I'm actually in the shop now to get the motor mount(s) fixed. Would bad ball joints, Tie rods, or the struts be the cost?

Tiny
Dave4989
May 9, 2011.
Those items mentiond would not have speed related noises.

KHLow2008
May 9, 2011.
I was told that 2 motor mounts (front and rear) had some cracks but were still good. The car doesn't bounce around when shifting nor do I feel viberations. The CV was inspected again and nothing Wrong was found. My suspension in general Is being questioned as I'm lowered about 3 inches. However this sound happened long after I dropped the car. Could this just be the struts going bad (when I replaced them the sound happened near the same time) or could it be a transmission problem?

Tiny
Dave4989
May 9, 2011.
Lowering the suspension can affect the drive train geometry and cause the problem. If it is the struts, it would not be speed related too. Struts fault noises would be any time as long as vehicle is moving.

KHLow2008
May 9, 2011.
I lowered my car 3 years ago. This noise began happening about 6 months ago. It has however gotten worse since then. It happened around the time I replace the CV and upgraded to koni insert struts. As mentioned I replaced the brakes and wheel bearing. Since I had this car I only replaced those plus a water pump. I have a vacuum leak and keep getting a p0420 code which I know what it is. Also once I got a code that mentioned something about the torque converter when I red lined it once. This noise (flat tire thump) happens alot mainly when I'm slightly accelerating above 10mph. If I floor it or give it alot of gas the sound disappears.

Tiny
Dave4989
May 10, 2011.
You mentioned checking the CV inner joints. Were they checked for excessive side movement and lack of grease?

KHLow2008
May 10, 2011.
It did move side to side and made a " sound wren you hit the trans. As for the grease
I have not seen any anywhere around. I suspected this to be the problem but the shop ensured me all cv's move a bit left and right. But the sound of
When it slaps is identical to what I get when accelerating. Plus the sound happened around the same time when installed.

Tiny
Dave4989
May 10, 2011.
I forgot to add. As much as I suspect the CV. I was told this couldn't be making the sound when accelerating. As mentioned the CV does move. But how much is too much play? You of course are referring to the entire cv moving or just sections

Tiny
Dave4989
May 10, 2011.
CV inner joints can make knocking noise, especially when accelerating. I would suggest getting a second opinion.
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KHLow2008
May 10, 2011.
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