Car rumbles and gets worse at higher speeds but sometimes smooths out?

2007 VOLVO XC70
220,000 MILES • 2.5L • 5 CYL • 4WD • AUTOMATIC
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SETHR89S
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I have the vehicle listed above that runs and drives great with the exception of one issue. This issue has taken me down a long dark tunnel of replacing parts. At around 45 MPH I develop a rumbling noise coming from the front of the vehicle. It lasts up until 55 to 60 mph and then smooths out. I noticed that the rumbling is there at slower speeds, but you need to be listening for it. I have replaced many parts trying to solve this issue. Those parts are:

Both front CV axles (entirely brand new, not rebuilt)

Driveshaft

Wheel bearings all the way around

Both front control arms

Both tie rods

Both front ball joints

All struts on vehicle

New brakes all the way around

New calipers on the front wheels

Alignment 3 times by different people

Wheel balance

Checked transmission and differential oils and they are all good

Replaced 2 of the motor mounts I could get to. I think there are two more.

Any ideas what could be causing this?
Jan 14, 2024 at 1:13 PM
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JACOBANDNICKOLAS
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Hi,

Wow, that's a lot. Are the tires worn evenly? Also, check to see if there are any loose plastic splash shields under the front.

If it is loud enough for you to record, please do so and upload it for me to hear.

Let me know.

Joe
Jan 14, 2024 at 8:04 PM
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SETHR89S
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So, I don’t see any loose plastic or anything. The tires could be worn unevenly but I moved tires around to see if the sound moved and it didn’t.

I’m really wondering if it might be those two engine mounts I didn’t get to, but I’m confused why they would cause an issue at highway speeds and not really low speeds. The only other thing I think it could be would be something with the transfer case or transmission, but nothing is leaking and everything shifts well.
Jan 14, 2024 at 8:44 PM
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STRAILER
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If I can help out here, to me it sounds like the drive shaft CV's and center support is worn out. I would remove the driveshaft for inspection. Here are the instructions on how to do so.
Check out the images (below). Please upload pictures or videos of the problem so we can see what's going on.

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Jan 15, 2024 at 9:22 AM
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SETHR89S
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I replaced both CVs and center support, and I replaced the driveshaft already.
Jan 15, 2024 at 9:27 AM
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JACOBANDNICKOLAS
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When you replaced the driveshaft, was the CV joint new where it mounted to the transfer case?

I agree with you. I feel a motor mount would make a clunk when shifting into gear and not just a rumble at a specific speed. However, anything is possible.

When you hear this, do you feel it in the steering, seat, floor, or in any part of the vehicle? Is it loud enough to record and upload for us to hear?

Let us know.

Joe
Jan 15, 2024 at 7:25 PM
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SETHR89S
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When I bought the driveshaft, it came new as a unit with brand new CV joints and a new center support bearing.
Image (Click to enlarge)
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Jan 16, 2024 at 2:21 AM
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SETHR89S
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I know this shows the other end of the driveshaft, but the new driveshaft was brand new with all new flanges and support bearing and everything. I didn’t rebuild a driveshaft.
Jan 16, 2024 at 2:23 AM
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STRAILER
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I have seen objects inside the tires cause this conditioner as well. Roll the tires over when they are off of the ground and try to hear if something is inside. Try rotating the tires front to rear.
Jan 16, 2024 at 9:18 AM
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JIS001
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Can you upload a video so we can listen to it? Also, when it starts to rumble, can you try and hit the accelerator pedal to see if by causing the transmission to downshift if the rumbling goes away. If it does, your transmission could be faulty. You may even want to buy some transmission fluid test kit to see if you have coolant/water contamination in the fluid.
Jan 16, 2024 at 9:29 AM