Creaking/Squeaking noise during acceleration or application of engine torque

**densmith123** · 05-30-2012

Fellow Grand Prix'ers:

I need some help troubleshooting the source of this noise. I have a 2006 baseline Grand Prix, 3.8L (VIN 2), 90,000 miles. Here are my symptoms and troubleshooting steps to date:

-When I accelerate normally, I hear 4-6 distinct creaking/squeaking/popping sounds as the drive train loads up with torque. When I let off the gas, it creaks/squeaks/pops the same number of times as the torque is unloaded. It is extremely annoying to hear this during every acceleration. If I accelerate and decelerate gently, I can reach highway speed without generating the sound but it annoys the people behind me.

-I have a moderate torque steer to the right during acceleration, enough to change lanes and drive off the shoulder if I were to let go of the steering wheel

-I originally thought it was a suspension problem. Me and my friend bounced the car in every possible direction without being able to duplicate the noise. I replaced all 4 struts AND strut mounts because I was told that they were weak during my State Inspection, and it improved my ride but did nothing to help the noise. I kept the same OEM springs though.

-I do not believe it is a suspension problem now... When I put the car in Drive with the parking brake set and my left foot on the brake, I can duplicate the noise with a quick rev of the accelerator even though the car is not in motion and there is no body movement. It seems to be coming from the front right side, according to outside observers. If I rev the throttle with the car in Park or Neutral, the noise is not there. The noise only appears under a drive train torque load.

At this point, I think it might be the lower right motor mount, but upon initial inspection the mount appears to be in good shape. I do not see any deteriorating rubber or any other obvious signs of it being bad. I disconnected my torque struts and rocked the engine on its two lower mounts and was not able to duplicate the noise.

Do you guys agree that it is the lower right motor mount, or is there any chance it could be:

-Exhaust pipe mating noise?
-Internal transmission noise?
-CV Joint noise?
-Something else?

Replacing the motor mount is going to be a huge undertaking for me since I will have to procure an engine hoist, but that's where I'm at unless someone can point me in another direction. I'm a pretty skilled DIY mechanic but cannot afford the time or money to get this one wrong. I'm hoping that somebody on this forum has dealt with this issue!

Thank you,
Denny Smith

**Sven the Sexman** · 05-30-2012

I may be out in left field on this, but it sounds like it could be worn lower control arms. Also, the aluminum subframes get worn in the area where the control arm attaches. Definitely possibility for some noise issues there. For the Engine mount if it is the problem, you can jack up on the oil pan with the mount unbolted from the subframe as the oil pan is the attaching point for the mount and therefore a structural unit.

**bmx6454** · 05-30-2012

did you say you "gunned it with the e-brake and brake engaged?? hopefully not in drive.. im no scientist, but thats probably not a good idea to do that..

**densmith123** · 05-30-2012

Bmx6454:

Yes, I revved the engine a few times with the brake and parking brake engaged, and in drive. I needed to apply torque to the wheels without the car moving, to rule out suspension noise associated with the pitching motion a car's body makes during a normal acceleration. When I did this quick test, I was able to generate the squeaking noise as the engine responded to this application of torque. "Gunned it" was probably a poor choice of words, it was a few quick revs with the brakes on.

If this procedure is not a good idea, I can accept the criticism, just please tell me why it's a bad idea, and offer an alternative if you can. Thanks for the help.

Hitman:

Thanks for the feedback, I will inspect those areas as well. That would be great if I could change the mounts without an engine hoist!

-Denny

**bmx6454** · 05-30-2012

okay, ill specify. its not a terrible idea, but too much throttle 4 too long will rip up the torque converter

**densmith123** · 05-30-2012

Bmx:

I totally agree with you, any extended power application would tear up the torque converter for sure. I see how my wording didn't properly describe what I was doing, and have edited the post so the readers know I was only doing a quick rev of the engine in drive with my foot on the brake. Thanks for your feedback, I can tell you know your stuff!

-Denny

**Rico** · 05-30-2012

Couple things to check:

Lower control arm bushings/LBJ
Cradle bolts - are they tight?
Bracket that connects engine to trans axle
Rack bolts tight?
Tie rod
Down pipe flex joint
Dog bone bracket bolts on the rad support
Upper and lower bolts on the lower engine and tranny mounts

For troubleshooting apply parking brake and chock tires...Requires two people. Have someone get in the drivers seat and repeat what you did with brake on and in drive. I think it will be quite obvious were the noise is coming from if the hood is open and you're right there while the noise is happening.

**bmx6454** · 05-30-2012

Thanks. But I don't really know that much. Especially compared to some of the guys on these forums. But on subject, I would either look at the engine mounts, or the axle joints(can't remember the exact name)

**Rico** · 05-30-2012

Originally Posted by bmx6454

Thanks. But I don't really know that much. Especially compared to some of the guys on these forums. But on subject, I would either look at the engine mounts, or the axle joints(can't remember the exact name)

Half shafts - CV and yoke

Yea, possibly.

**densmith123** · 05-31-2012

Rico, BMX:

Awesome, I will check all of these areas and let you guys know what I find. Thanks.

-Denny

**densmith123** · 06-05-2012

Forum readers:

Just to conclude this thread, I found the source of the problem tonight and fixed it. It was my front right wheel bearing.

To troubleshoot, I had my friend rock the car forward and backward, with the car turned off and in PARK, and we were able to duplicate the noise. I put my hand on the CV Halfshaft and felt some clicking, and then traced the noise to the hub assembly which could be heard quite clearly on the hub cap.

This was a strange wheel bearing problem. I did not have any noise from it while driving (no grinding/whirring/roaring), only the squeaking and creaking whenever torque was applied either during acceleration or braking. I would also hear a clunk sometimes when putting the car in gear or hitting a dip.

Take this lesson for what it is worth... this had been a mystery to me for a month and now it's solved. Thanks to each of those that took the time to chime in with suggestions!

-Denny