Scratching noise at highway speeds?

[futureman]

Hello everyone... This is my first post on the forum, so i hope this question is in the right category?

Basically i bought an automatic '02 dream cruiser about three years ago... it was second hand, and i immediately noticed a scratching noise at around 60-65mph... only when the accelerator is depressed a little bit to maintain speed, if i take my foot off the gas or floor it, the sound goes away.

The scratching sound seems to be coming from the right front of the car, but due to resonance and all, i can not be completely sure!?!?

I took it to the dealer three years ago and they said they did not know what it was... not a big surprise since they are fairly incompetent in my town... but i figured it would break before my warranty was out, well my maximum care expires in three months... so what could it be? It has 65K miles.

Thanks in advance for the help!

[Candyman]

Hey futureman,

Unfortunately their could be a lot of things that could produce the noise so its a bit tough to give you a firm diagnosis. Honestly, my best advice would be to start with the basics, and work your way up from their. Maybe get down and take a good close look to make sure you don't have any plastic like the inner fender well, or something lightly rubbing which seams to be making noise, or if you might be running a little bigger tire, make sure its not rubbing a bit, stuff like that. I know its pretty basic, but I am trying to work out a process of elimination to try to get to the root of the problem.

Next, if nothing is rubbing, I might check out the tires themselves! Once upon a time, I had a kind of scratching , or grinding noise once upon a time. I swore it was a wheel bearing, and replaced both of them up front, but much to my dismay, after the work was done, the problem still persisted. So, after reading a ton of posts, and doing a bit of homework, I found several people who went and changed their tires, and the noise went away! I was skeptical, but I went ahead and

[CREWZIN]

Welcome to the forum.

You might want to check around different shops to see who has a lift that will let the wheels turn when you in the air. Someone stays in the PT while it's lifted up and runs the car so the wheels and drive train move under load and the mechanic on the ground can look on both sides for the scraping noise that your hearing.

[futureman]

I actually have 2 sets of tires, snow and regular, and the noise is the same with both of them... the brakes were also redone about a year ago, and the noise did not change... so that rules out those 2 issues.

Any help would be greatly appreciated... if i posted a .wav file of the sound, do you think that would aid in the diagnosis?

[bertone]

Originally Posted by futureman

if i posted a .wav file of the sound, do you think that would aid in the diagnosis?

Definitely...

[futureman]

OK i will record the sound, and post it when i get the chance... in the meantime are there any more ideas as to what it could be?

[soonercruiser]

Agree...first check the easy stuff like rubbing.
I had a Subaru FWD back in the late 1980's that I believe had a similar problem; the noise under acceleration noise is likely to be drive train related....I believe that mine was.

[BLUEH20]

Look for a venturi, wind shear or heat sheild issue.

The thing that points me to this 1) happens at a given speed 2) happens at a given throttle position 3) can be duplicated by the owner/marjority driver.

Seriiously doubt you will find anything with the vehicle on a lift with wheels unloaded and all suspension unlaoded. This set up will aslo change the geometry of the drive train--all these make me doubt you will get the noise to duplicate.

Chrysler has a diagnostic tool refered to as EVA (electronic vibration analysis) that in the right hands can be very good at find vibration on the road and on the rack. By using frequency and harmonics it can point to specific area--tires, bearing, belts, etc.

I personally believe that you have a venturi or heat/chaffing shield issue.

A product that can help find problems in these situatiions is "Mouse Ears". These are a series of re-locatable microphones that can be placed at various locations on the vehcile to help isolate a sound.

You are looking at a large diagnosis effort that may fall directly in your lap if there is not a covered issue as called out in your Service Contract.

I do wish you the best of luck and please keep us informed as to what you do and what is found.

[futureman]

Thanks for all the replies thus far...

OK i finally got around to recording the sound... i could not figure out how to attach an MP3, so i just made it into a video and uploaded to vimeo:

http://www.vimeo.com/3288116

I recorded it with an iphone, so the quality is a little bad... and in real life there is a scratching sound under the whining sound you can hear under light throttle at about 55mph...

Thanks in advance to all the experts on this board for helping me out!

[CREWZIN]

Well, that takes me out......

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