bump sound in rear

2005 TOYOTA SIENNA
128,000 MILES • 3.3L • V6 • 4WD • AUTOMATIC
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IMAGING
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When driving, every now and then, feel a bump in the rear like when someone bumps you in the back or you have heavy luggage or equipment in the back and moves around and bumps.
Nov 23, 2021 at 6:37 AM
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JACOBANDNICKOLAS
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Hi,

Is there anything that seems to prompt this to happen? For example, do you need to hit a bump, or does it happen when turning?

Since you mentioned it seems like something is moving around, the first thing I'm going to suggest is to check the rear suspension under the vehicle. Check for anything that is loose or damaged. Inspect bushings as well. Also, see if you are able to move the exhaust around that wound indicate a bad rubber mount.

I attached a pic below showing the rear of the vehicle. Check the things I highlighted and let me know what you find.

Take care,

Joe

See pic below.
Nov 23, 2021 at 8:28 PM
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IMAGING
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In the pic you sent that's below, where is the rear suspension?
Nov 24, 2021 at 6:09 AM
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IMAGING
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Also, let's say a tensioner bolt is loose in one of the belts (drive belt, power steering belt or timing belt), will that cause a squeaking sound to the engine on start-up?
Nov 24, 2021 at 7:55 AM
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JACOBANDNICKOLAS
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Hi,

The pic is showing what is called an exploded view of the rear suspension. It identifies the components as seen when they are apart.

As far as the belt noise, yes if the belt has become loose. If the sound goes away after startup, the first thing I would check is the alternator belt. When the car first starts, there is a quick heavier load placed on it.

If you check it and find it's loose, it should be tightened. If you look at the pic below, you will need to loosen bolts A and B first. Then, tighten bolt C which is the adjuster until the belt is tight.

Let me know what I can do to help.

Take care,

Joe
Nov 24, 2021 at 9:15 PM
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IMAGING
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I tightened all the bolts since I had to replace and install a new drive(alternator) belt. I felt the belt tight. How do I determine if the belt is as tight as it should be?
Nov 26, 2021 at 12:20 PM
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JACOBANDNICKOLAS
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Hi,

If you look at the pic below, I highlighted where to test. You should be able to move the belt approximately 3/4" (deflection) up and down.

Let me know if this helps.

Joe

See pic below.
Nov 26, 2021 at 9:11 PM
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IMAGING
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Now, if it's too tight, will it squeak also?
Nov 27, 2021 at 4:52 PM
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JACOBANDNICKOLAS
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Hi,

If it's too tight, chances are it won't. However, being over tight can damage the bearings in the components it turns.

Are you still having trouble with the noise? Is it possible for you to record it and upload it for me to hear?

Let me know.

Joe
Nov 27, 2021 at 10:27 PM
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IMAGING
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The noise is only when turning the ignition on for one second only. It doesn't make any noise when revving up or driving around.
Nov 28, 2021 at 5:25 PM
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JACOBANDNICKOLAS
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If it only happens when you first start it, my first suspect is the alternator belt isn't tight enough. Do this: Start the engine and let it idle. Turn everything electrical on in the vehicle (light, wipers, heater, brake lights, anything you can think of. Hit the throttle. Does it make noise then?

Let me know,

Joe
Nov 28, 2021 at 6:38 PM
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IMAGING
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No, it doesn't make noise with everything electrical on and hitting the throttle, revved up to 4,000 RPMs.
Nov 30, 2021 at 9:26 AM
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JACOBANDNICKOLAS
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Okay. Is it possible for you to record it, and upload the recording for me to hear what is happening?

Let me know.

Joe
Nov 30, 2021 at 4:01 PM