Odd vibration in a 2007 Cadillac AWD STS

[BobsArmory]

My wife and I just bought a used 2007 All Wheel Drive Cadillac STS V-6 a few weeks ago and have recently found an odd vibration that starts around 70 to 75 MPH.

The vibration is a low frequency vibration that can be felt in the steering wheel, seat and floor. You can even barely hear it just above the road and wind noise. Kind of reminds me of the sound a Blackhawk Helicopter (low pitched thumping hum) makes when it is coming toward you but like I said the sound of the vibration is just barely above the road and wind noise.

Any thoughts on where I might start looking?

 

[Fleetmon]

Our 528i made a helicopter-type noise when the wheel bearings were failing and there was a minor vibration. Tires can make some 'copter type noises too.

 

[Doog]

Well first have all 4 tires balanced and have the tech check the rims for any out of round or curb damage. Then be sure the face of the hub and inside of the wheels are clean where they mate and there is no runout there. Have the tech look closely for any cord defects in each tire. Over inflate each tire 2psi over what is on the door sticker. Make sure if you have direction tires that they are all rotating in the correct direction.

Next, while the car is on the lift, inspect the CVJs and drive shafts and joints for any loose play or deflection. Roll each wheel to see if you hear a bearing grinding.

If you don't find anything obvious then you have to go to a Caddy dealer and have them put microphones on the drivetrain components and drive it on the freeway at 70-80mph. That will find it.

 

[GMBoy]

Here is the offical GM vibration diagnostic check sheet which may help you:
**sorry the cut and paste format sometimes looks funny and has strange characters. Not sure why.





xTooltipElement
Service Information 2007 Cadillac STS | STS VIN D Service Manual | Document ID: 3287275
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#03-00-91-001F: Vibration Analysis Worksheet - (Feb 19, 2013)
Subject: Vibration Analysis Worksheet

Models: 2014 and Prior GM Passenger Cars and Trucks


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This bulletin is being revised to add models years and to change the location of the EVA readings requested. Please discard Corporate Bulletin Number 03-00-91-001E (Section 00 – General Information).


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When diagnosing vibration concerns, use the following worksheet in conjunction with the appropriate Vibration Analysis-Road testing procedure in the Vibration Correction sub-section in SI. FILL OUT ONLY THE APPLICABLE PORTION OF THE WORKSHEET THAT APPLIES TO THE VIBRATION / NOISE.

Refer to the appropriate section of SI for specifications and repair procedures that are related to the vibration concern.

Vibration Analysis Worksheet

To:

Dealer:

Fax Number:

 

VIN__ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __

 

 

Procedure Performed By:

Date:

Model:

Year: Gear Ratio:

Odometer:

VIN __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __

TAC Case #, if applicable:

Conditions During Road Test Procedures

As condition occurs: Engine RPM_____________


Vehicle Speed__________________

Vibration/Noise detected during the following road test procedures:

Engine RPM_______________ Vehicle Speed_______________

Slow Acceleration Test: Yes__________ No__________

Neutral Coast-Down Test: Yes__________ No__________

Downshift Test: Yes__________ No__________

Neutral Run-Up Test: Yes__________ No__________

Brake Torque Test: Yes__________ No__________

Steering Input Test: Yes__________ No__________

Standing Start Acceleration (Launch Shudder) Test: Yes__________ No__________

Vibration/Noise Eliminated with TCC Commanded On: Yes__________ No__________

Vibration/Noise Eliminated with TCC Commanded Off: Yes__________ No__________

Vibration/Noise Duplicated on Hoist: Yes__________ No__________

When using the EVA, always take a snapshot. This will help determine which vibration shows up the most.

Important: Vibrate software can also be used to assist in vibration diagnosis. Refer to Vibrate Software Description and Operation in SI.

EVA Readings

Refer to Electronic Vibration Analyzer (EVA) Description and Operation in SI for more detailed information.


Important: As a reminder, place the EVA sensor where the vibration is felt by the customer or on the test drive ie: if the vibration complaint is from the seat then place the sensor on the seat track, if the vibration complaint is from the steering wheel then attach the sensor to the steering column. Ensure the word “UP” on the sensor is physically facing up. The typical areas are the seat track, the steering column or the instrument panel. Locating the EVA sensor on additional area (i.e. the right fender, left fender, right quarter panel, left quarter panel, rear seat track, etc.) may also assist in determining the component causing the vibration/noise. The key is to look for the same Hz reading with the greatest amplitude G readings.

 

FILL OUT ONLY THE APPLICABLE PORTION OF THE WORKSHEET THAT APPLIES TO THE VIBRATION/NOISE:

 

Sensor at Steering Column:

1st Line MPH/KPH:__________ HZ:__________ Gs:__________

2nd Line MPH/KPH:__________ HZ:__________ Gs:__________

 

Sensor at Drivers Seat Rail:

1st Line MPH/KPH:__________ HZ:__________ Gs:__________

2nd Line MPH/KPH:__________ HZ:__________ Gs:__________

 

Sensor at Passenger Seat Rail:

1st Line MPH/KPH:__________ HZ:__________ Gs:__________

2nd Line MPH/KPH:__________ HZ:__________ Gs:__________

 

Driveshaft Runout:

Is runout within specification? Yes__________ No__________

Initial: Frt:__________ Center:__________ Rear:__________ Stub Shaft:__________

Current: Frt:__________ Center:__________ Rear:__________ Stub Shaft:__________

Pinion Flange Runout Reading:__________

Has a system balance been attempted: Yes__________ No__________ (If no, perform a System Balance)

Were the drums removed to system balance? Yes__________ No__________

Initial: HZ__________ Gs__________

Current: HZ__________ Gs__________

Hose clamps added: Yes__________ No__________

Prop shaft indexed? Yes__________ No__________

If a System Balance has been attempted but the vibration is still present or system balance was not able to be achieved, check the ring gear backlash in eight different spots on the ring gear. Note that excessive ring gear runout may result in a first order tire speed or first order prop shaft speed concern.

Backlash in eight equal spots on the ring gear (readings should not vary more than 0.002 in (0.050 mm)):

1__________ 2__________ 3__________ 4__________ 5__________ 6__________ 7__________ 8__________

Does the vehicle have any of the following components attached?

Pinion damper: Yes__________ No__________

Pinion flange damper: Yes__________ No__________

Exhaust damper: Yes__________ No__________

Initial: Front angle:__________ Center Angle:__________ Rear Angle:__________

Current: Front angle:__________ Center Angle:__________ Rear Angle:__________

Were shims added to the following?

Transmission/transfer case mount: Yes__________ No__________

Pinion nose (rear springs): Yes__________ No__________

Center Support Mount: Yes__________ No__________

Tire Size and Brand:_____________________________________

 

Record wheel balance information below if available record weight information prior to balance and after balance.

 

Wheel/Tire balance

Right rear: Inner Weight:__________ Outer Weight:__________

Left rear: Inner Weight:__________ Outer Weight:__________

Right front: Inner Weight:__________ Outer Weight:__________

Left front: Inner Weight:__________ Outer Weight:__________

Wheel/Tire Runouts on vehicle (max. 0.050 in (1.27 mm))

Refer to the latest version of Corporate Bulletin Number 00-03-10-006 for tire radial force variation information.

Right rear: Inner lateral:__________ Center radial:__________

Left rear: Inner lateral:__________ Center radial:__________

Right front: Inner lateral:__________ Center radial:__________

Left front: Inner lateral:__________ Center radial:__________

Mounting surface runouts (max. 0.005 in (0.127 mm))

Flange, right rear:__________ Hub, right front:__________

Flange, left rear:__________ Hub, left front:__________

Wheel stud runouts (max. 0.008 in (0.203 mm))

Flange, right rear:__________ Hub, right front:__________

Flange, left rear:__________ Hub, left front:__________











GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

© 2013 General Motors. All rights reserved.

 

[GMBoy]

And a service bulletin for AWD models...sorry the pictures would not cut and paste..however I can email you all this if you like. PM me.




xTooltipElement
Service Information 2007 Cadillac STS | STS VIN D Service Manual | Document ID: 1874730
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#PIC4326A: Growl Shudder Vibration Or Exhaust Ground Out On Accel - keywords AWD acceleration mount noise transmission - (Nov 30, 2006)
Subject: Growl, Shudder vibration, or Exhaust Ground Out on Accel

Models: 2007 Cadillac STS and SRX with 3.6L and AWD built prior to VIN breakpoint 70142728


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This PI has been superseded to include images of the condition and description of the distance between the tab and the cross member on "good" and "bad" mounts. Please discard PIC4326.


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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:A customer may comment about a growl noise, shudder vibration, or exhaust ground out condition when accelerating. This concern can be reproduced while brake torquing the vehicle.

Recommendation/Instructions:Inspect the rear transmission tab that goes through the middle of the mount. If the tab is in hard contact with the bottom of the mount, replace the mount. The part number for the mount does not change. Figure 1 shows a mount with this condition. There is a gap of about 6mm between the bottom edge of mount tab and the cross member. Figure 2 shows a mount without the condition. There is a gap of about 14mm between the tap and the cross member.





Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

© 2013 General Motors. All rights reserved.

 

[GMBoy]

Another possibilty:



xTooltipElement
Service Information
2007 Cadillac STS | STS VIN D Service Manual | Document ID: 1758171
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Drive Belt Rumbling and Vibration Diagnosis
Diagnostic AidsThe accessory drive components can have an affect on engine vibration. Vibration from the engine operating may cause a body component or another part of the vehicle to make rumbling noise. Vibration can be caused by, but not limited to the A/C system over charged, the power steering system restricted or the incorrect fluid, or an extra load on the generator. To help identify an intermittent or an improper condition, vary the loads on the accessory drive components.

The drive belt may have a rumbling condition that can not be seen or felt. Sometimes replacing the drive belt may be the only repair for the symptom.

If replacing the drive belt, completing the diagnostic table, and the noise is only heard when the drive belts are installed, there might be an accessory drive component with a failure. Varying the load on the different accessory drive components may aid in identifying which component is causing the rumbling noise.

Test DescriptionThe numbers below refer to the step numbers on the diagnostic table.

2.This test is to verify that the symptom is present during diagnosing. Other vehicle components may cause a similar symptom.
3.This test is to verify that one of the drive belts is causing the rumbling noise or vibration. Rumbling noise may be confused with an internal engine noise due to the similarity in the description. Remove only one drive belt at a time if the vehicle has multiple drive belts. When removing the drive belts the water pump may not be operating and the engine may overheat. Also DTCs may set when the engine is operating with the drive belts removed.
4.Inspecting the drive belts is to ensure that they are not causing the noise. Small cracks across the ribs of the drive belt will not cause the noise. Belt separation is identified by the plys of the belt separating and may be seen at the edge of the belt our felt as a lump in the belt.
5.Small amounts of pilling is normal condition and acceptable. When the pilling is severe the drive belt does not have a smooth surface for proper operation.
9.Inspecting of the fasteners can eliminate the possibility that the wrong bolt, nut, spacer, or washer was installed.
11.This step should only be performed if the water pump is driven by the drive belt. Inspect the water pump shaft for being bent. Also inspect the water pump bearings for smooth operation and excessive play. Compare the water pump with a known good water pump.
12.Accessory drive component brackets that are bent, cracked, or loose may put extra strain on that accessory component causing it to vibrate.
Drive Belt Rumbling and Vibration Diagnosis Step
Action
Yes
No

Notice: Refer to Belt Dressing Notice.

DEFINITION: The following items are indications of drive belt rumbling:

•A low pitch tapping, knocking, or thumping noise heard at or just above idle.
•Heard once per revolution of the drive belt or a pulley.
•Rumbling may be caused from:
– Pilling, the accumulation of rubber dust that forms small balls (pills) or strings in the drive belt pulley groove
– The separation of the drive belt
– A damaged drive belt
DEFINITION: The following items are indications of drive belt vibration:

•The vibration is engine-speed related.
•The vibration may be sensitive to accessory load.

1
Did you review the Drive Belt Symptom operation and perform the necessary inspections?
Go to Step 2
Go to Symptoms - Engine Mechanical

2
Verify that there is a rumbling noise or that the vibration is engine related.

Does the engine make the rumbling noise or vibration?
Go to Step 3
Go to Diagnostic Aids

3
 1. Remove the drive belt.
If the engine has multiple drive belts, remove the belts one at a time and perform the test below each time a belt is removed.

 2. Operate the engine for no longer than 30–40 seconds.
 3. Repeat this test if necessary by removing the remaining belt(s).
Does the rumbling or vibration still exist?
Go to Symptoms - Engine Mechanical

or

Go to Vibration Analysis - Engine
Go to Step 4

4
Inspect the drive belts for wear, damage, separation, sections of missing ribs, and debris build-up.

Did you find any of these conditions?
Go to Step 7
Go to Step 5

5
Inspect for severe pilling of more than 1/3 of the drive belt pulley grooves.

Did you find severe pilling?
Go to Step 6
Go to Step 7

6
 1. Clean the drive belt pulleys using a suitable wire brush.
 2. Reinstall the drive belts. Refer to Water Pump and Generator Belt Replacement and Air Conditioning Compressor and Power Steering Pump Belt Replacement.
Did you correct the condition?
Go to Step 8
Go to Step 7

7
Install a new drive belt. Refer to Water Pump and Generator Belt Replacement and Air Conditioning Compressor and Power Steering Pump Belt Replacement.

Did you complete the replacement?
Go to Step 8
Go to Step 9

8
Operate the system in order to verify the repair.

Did you correct the condition?
System OK
Go to Step 9

9
Inspect for improper, loose or missing fasteners.

Did you find any of these conditions?
Go to Step 10
Go to Step 11

10
Notice: Refer to Fastener Notice.

 1. Tighten any loose fasteners. Refer to Fastener Tightening Specifications.
 2. Replace improper or missing fasteners.
Did you complete the repair?
Go to Step 13
Go to Step 11

11
Inspect for a bent water pump shaft. Refer to Water Pump Replacement.

Did you find and correct the condition?
Go to Step 13
Go to Step 12

12
Inspect for bent or cracked brackets.

Did you find and correct the condition?
Go to Step 13
Go to Diagnostic Aids

13
Operate the system in order to verify the repair.

Did you correct the condition?
System OK
Go to Step 3

© 2013 General Motors. All rights reserved.

 

[GMBoy]

There is a TON of info, and most won't copy and paste clearly here. But here is another 'brief" mentioned in the GM manual:


 1. Inspect the following components for wear and/or damage:
◦Inspect the propeller shafts for dents, damage, missing weights, and/or undercoating.
◦Inspect the U-joint, or joints, if equipped, for excessive wear, looseness, and/or damage.
◦Inspect the prop shaft constant velocity (CV) joint, or joints, if equipped, for excessive wear, looseness, and/or damage.
◦Inspect the prop shaft coupler assembly, or assemblies, if equipped, for excessive wear, looseness, and/or damage.
◦Inspect the prop shaft support bearing, if equipped, for damaged rubber components, worn bearings, looseness, and/or a deformed or cracked bracket.
◦Inspect the drive axle mounts, if equipped, for excessive wear, looseness, and/or damage.
 2. Replace any of the components found to be worn or damaged.

 

[salv]

first thing to do is turn the front wheels and inspect the tires for any uneven wear, especially up the inner edge. if there are high and low spots or cupping, replace the tires to eliminate the noise.

 

[Papa Bear]

Some of those vehicles, if you drive them with the back window open, will cause a resonance that will drive you out of the car.

My friend recently got a 2007 Impala and thought the car was coming apart when going down the road with the rear windows cracked open.

 

[BobsArmory]

I over inflated 2 PSI like you mentioned and the vast majority of the issue has disappeared!

Originally Posted By: Doog
Well first have all 4 tires balanced and have the tech check the rims for any out of round or curb damage. Then be sure the face of the hub and inside of the wheels are clean where they mate and there is no runout there. Have the tech look closely for any cord defects in each tire. Over inflate each tire 2psi over what is on the door sticker. Make sure if you have direction tires that they are all rotating in the correct direction.

Next, while the car is on the lift, inspect the CVJs and drive shafts and joints for any loose play or deflection. Roll each wheel to see if you hear a bearing grinding.

If you don't find anything obvious then you have to go to a Caddy dealer and have them put microphones on the drivetrain components and drive it on the freeway at 70-80mph. That will find it.

 

[Doog]

Originally Posted By: BobsArmory
I over inflated 2 PSI like you mentioned and the vast majority of the issue has disappeared!


Ok (like in my pm) now get the tires on a Hunter Road Force balancer and that machine will tell you if you have a tire out of round or a bent wheel. If the balance values on any of the 4 tires is over 20 have them index the tire on the rim. While each tire comes off check the face of the hub for rust as well as the back of each wheel so you get a flat seal at the face when you re-install each wheel onto the car.

Find a Hunter machine on here:

http://www.gsp9700.com/search/findgsp9700.cfm