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This might sound crazy but I was wondering if anybody has heard a very loud whirring type noise when their wheel bearings went bad? When the noise first started I thought that my auto level air suspension compressor was running all the time because that's what it sounds like. I also noticed a that the front end was not quite right. I really can't describe how, I just know from driving it all the time. I took it by the Caddy dealer and had them check the compressor and front suspension. Sure enough they said the compressor was bad and wanted $860.00 to fix it. They also said that they noticed new tires on the car and that the reason I thought the front end was not right was because they probably balanced the tires wrong. I am not an idiot so I declined all services, paid them their fee for looking at it and went on my way. Well now the noise is worse and I notice that it corresponds with my speed. The faster I go, the louder the whirring. As I slow down the noise gets quieter and then goes away at stop. I am guessing that it's not the compressor at all but some other mechanical noise, possibly a bearing or maybe even the tranny. Any thoughts? I trust you guys a lot more than taking it to yet another dealer!

Jack the car up, and see if there's play in the wheels. If there is, then the bearing is bad on that side.

The noise for the wheel bearing usually starts around 30 mph.

Yeah, about 30mph is where I start to hear it. I feel silly for thinking that it was the compressor but that is exactly what it started out sounding like. The noise is much more pronounced and consistant over the last few days. I really can't do anything with it myself until the weekend plus it's been pouring rain. I guess I'll have to risk damaging the spindle.

Generally, the bearing can make noise for some time before it causes any other problems. Waiting a bit for dry weather shouldn't hurt anything.

If the compressors running all the time, it certainly isn't broke??? Your rear would be high and the front low. If it is still running continuously, I would be looking to see if the leveling rod came off,(behind the drivers rear tire, on left side) or the leveling switch has gone bad. (I recall one GXP having that happen) I wouldnt go back to that Dealer) Quite a few GXP owners have reported premature front wheels bearing failure. Seems to be turning into a common problem. Don't assume because there is no play, the bearing isn't bad. Have any grease on your rims? If it's making noise, I would definitely pull the rotor and inspect it closely. By the time they get to having play, you could lose it outright. Hell of a ride I've experienced myself.

Thanks for all the advice. Turns out it was front wheel bearings. Had both hubs replaced today and it's back to normal. The compressor is working fine. The weird thing is that it sounded exactly like the compressor that went bad in my Navi. It's pretty hard to tell where the noise is coming from while your driving it. It finally dawned on me that if the compressor was that bad, it would be running even at stop. I can't believe that the dealer told me the compressor was bad and the front end was fine! Sam's club should offer wheel bearings and steering shafts by the gross, they'd make a fortune.

Glad it worked out. I thought my driver's front was going bad. About 15 mph, I'd get that 'humm" from it. Turned out, it was simply a tire... I found this out when I did a rotation and it went away. :D

Anyway, another way to tell a worn bearing is getting it up in the air, putting the trans in nuetral and spinning the fronts. It'll be harder than the rears (obviously) as you're turning the trans too, but even still after you stop physically spinning it with your hands, it should spin freely some. A worn bearing will almost have no free spin after. Or spin each side (this is presuming only one is bad), if one feels tighter than the other, that's a good indicator.

Or,with the car in the air and in neutral you can spin the tire and hold the spring in your hand and you can actually feel the "grating" of a bad bearing,compare both sides and one side will feel noticeably smoother.Or,while driving,lets say your passenger side is bad,if you swerve the sound the bearing makes will change(like a lane change type of swerve).When swerving left it will get louder because it puts more pressure on the bearing,when swerving right it will get quieter because of less pressure.