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If this should not be in this directory, I apologize but I could not find a DTS folder so this seemed like the closest.

I know you all will think I am off my rocker but it's the truth.

I have a 2008 DTS with 90,000 miles. It has always been perfectly maintained.

Several months ago it began to make a high pitched whining sound only at high speed, 65 MPH+ but, here's the kicker, it only does it when it is hot outside, 80-85+.

I drive one way to work, 31 miles, all highway. I drive between 60-80 MPH depending on traffic. In the morning, the car purrs like a kitten. In the afternoon / evening heat, the car whines, almost like the finger nails on a chalkboard type sound. It starts at about 63-64 MPH and gets louder as I get faster.

I have had it to multiple mechanics and no resolve.

First a mechanic told me to replace the rear bearing which I did.

Then they said it was a steel belt in a tire. The tires had some miles on them so I replaced all 4.

Then they said it was the fron wheel bearings and the front sway bars so they were all replaced.

Then they said it was something in the brakes so they were all replaced, new rotors, new ceramic pads, new hardware....

They have also changed both front wheel bearings a second time within 6 months.

Still whines.

I have a video showing the dash speed and you can hear the noise as it passes 63 MPH that I have posted http://www.numburz.net/Cadillac/VIDEO0003.mp4

I am lost and looking for any answers that can be offered.

Thanks

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Nice job posting a video; that is an interesting problem. My impression is something rubbing on a tire but only at certain speeds -- perhaps a bit of trim only reaches the tire if the windspeed hitting the trim is sufficient?

Transients that occur at a speed range and then correct at higher speeds would be a join issue. This seems to me to be a mechanical problem.

Bruce

2016 Cadillac ATS-V gray/black

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Nice job posting a video; that is an interesting problem. My impression is something rubbing on a tire but only at certain speeds -- perhaps a bit of trim only reaches the tire if the windspeed hitting the trim is sufficient?

Transients that occur at a speed range and then correct at higher speeds would be a join issue. This seems to me to be a mechanical problem.

Bruce,

Thanks, I thought it might be a wind or trim issue as well but it doesn't does it when the outside temp is below 80 degrees so I continue to be lost and the mechanics are just having a field day with my wallet.

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The temp would still suggest a mechanical problem to me -- something that when it is HOT also can touch on the wheels.

How do your brake disks and brake pads look? When was the last time they were changed?

Bruce

2016 Cadillac ATS-V gray/black

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Interesting problem.

I would check for air leaks around the windshield maybe the heat opens a gap.

What kind of roof does your car have, I had a noise that DROVE me CRAZY and I never found it till it was too late, my fake convertible top on my 91 broke loose and air was getting under the front edge of it and it was vibrating, one day the wind grabbed it and ripped it off violently and the roof shell hit the car behind me. Check the leading edge of your vinyl or cloth top.

I would also check the HVAC aspirator, its a little fan like your laptop cooling fan, that pulls air into the dash over a temp sensor. When they go bad they whine.

Have you listened closely to your speakers?, humor me, I know it sound odd, but I am listening to a recording here. Maybe this is a capacitor in a bose amp whining when its hot.

Other than that, I am stumped, it sounds too clear to be a whine from a tensioner or an idler wheel and I dont see how those items could be speed or temp sensitive.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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My 2006 was doing something similar to that... but not till I passed about 80.

There is a rubber flap under the leading edge of the hood.

You can see it when you open the hood...

They replaced that and the noise went away.

To see if that is what it is...take some duct tape and tape the flap up for a couple of days... see if it makes any difference.

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Good thought Jim, this problem requires some out of the box thinking

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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The temp would still suggest a mechanical problem to me -- something that when it is HOT also can touch on the wheels.

How do your brake disks and brake pads look? When was the last time they were changed?

Bruce,

That was one of the things the mechanics thought. Completely knew rotors, hardware, and ceramic pads less than 60 days ago.

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Interesting problem.

I would check for air leaks around the windshield maybe the heat opens a gap.

What kind of roof does your car have, I had a noise that DROVE me CRAZY and I never found it till it was too late, my fake convertible top on my 91 broke loose and air was getting under the front edge of it and it was vibrating, one day the wind grabbed it and ripped it off violently and the roof shell hit the car behind me. Check the leading edge of your vinyl or cloth top.

I would also check the HVAC aspirator, its a little fan like your laptop cooling fan, that pulls air into the dash over a temp sensor. When they go bad they whine.

Have you listened closely to your speakers?, humor me, I know it sound odd, but I am listening to a recording here. Maybe this is a capacitor in a bose amp whining when its hot.

Other than that, I am stumped, it sounds too clear to be a whine from a tensioner or an idler wheel and I dont see how those items could be speed or temp sensitive.

Lots of suggestions, thanks so much. It is a straight metal roof, no mock top, no sunroof.

We have had the windshield checked because they did think an air leak at first but no leaks are gaps have been identified.

The HVAC aspirator...not something that has been checked to my knowledge so that is one for the possible remedy list.

As to the radio / speakers, my wife and i have tried to pinpoint the issue and thought perhaps it was a humming speaker. On multiple occasions we have turned the radio off / on/ changed inputs / stations etc. No change in the radio makes a difference, even completely turning the radio off. We also ran through these tests with the AC system as well and changes to that including completely turning it off also have made no difference.

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My 2006 was doing something similar to that... but not till I passed about 80.

There is a rubber flap under the leading edge of the hood.

You can see it when you open the hood...

They replaced that and the noise went away.

To see if that is what it is...take some duct tape and tape the flap up for a couple of days... see if it makes any difference.

Jim,

I haven't tried your solution yet but Murphy's Law tells me after dropping nearly $2,700 in repairs chasing this problem, it will be 25 cent piece of duct tape that solves the problem. I'll give it a look and try and let you know. Thanks.

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My 2006 was doing something similar to that... but not till I passed about 80.

There is a rubber flap under the leading edge of the hood.

You can see it when you open the hood...

They replaced that and the noise went away.

To see if that is what it is...take some duct tape and tape the flap up for a couple of days... see if it makes any difference.

Jim,

I haven't tried your solution yet but Murphy's Law tells me after dropping nearly $2,700 in repairs chasing this problem, it will be 25 cent piece of duct tape that solves the problem. I'll give it a look and try and let you know. Thanks.

I know what you mean about Murphy...

I have been down THAT road a few times...

I hope it is something as simple as what I mentioned... your noise sounds almost exactly like mine did.

The first time I heard it, I thought it sounded like a train horn... off in the distance.

I had owned the car for about a year when it started happening.

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Wouldnt that be nice if it were something simple like this, something tells me that this is the answer. Personally, I think if this is the problem, a GM bulletin should be issued due to the number of mechanics that have been baffled by this problem. You may find a clean rubbing spot on the under hood area where it meets if you look

I guess that the heat softens it enough to become flexible so the the air causes it to oscillate

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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