[roadtrip56]

Hi, I'm new to the forum and this is my first post. I'll do a full intro to the community
later.

I have a 2009 CTS base model with 114K miles on it. We're the original owners.

About 2 weeks ago we started noticing a rumble at about 50mph. It's not a squeal,
more of a growling sound with a constant vibration. I can't hear anything extra with the
windows down. I haven't been able to isolate it as front, back, left or right.

It doesn't matter what the road surface is like. It gets a little louder at higher speeds.
Turning left makes it louder, turning right makes it quieter. Braking or shifting into
neutral and coasting makes no difference.

I had the brakes done and they pull tested so bearings are not likely. Wrong sound
anyway. New OE pads and rotors turned, no change.

I've read about the Drone/Vibration issue here on the forum and while there are
similarities, this was not an ongoing issue. This 09 has been quiet and smooth from
day 1. The drive shaft has never been disconnected so I would doubt an indexing
issue.

I had a fluid change done yesterday and the guy did a road test. He thinks bearing but
the pull test was good and the sound is very-very low pitched. It isn't a whine so I
have doubts about the read differential, but it's possible.

I did notice that my coolant fan is making a noise that sounds like the same frequency
and I don't remember it doing that before. The right left turning change makes me
skeptical but I'm going to change it tomorrow anyway.

Any of this sound familiar to anyone?

TIA

 

[kkuz]

I would look deeper into differential or exhaust system gaping. In both cases turning can change the level of noises. What did you do with brakes? What was the reason of servicing them?

 

[roadtrip56]

It was time for a brake job, 114K miles on the original pads. Needless to say my wife isn't hard on the brakes

New pads, turned the rotors and replaced the fluid.

 

[tinman]

Still sounds like a bearing. The turning left/right issue tells me a front bearing.

 

[RAB]

I wonder if there might be an issue with a failing or dry CV (constant velocity) joint.
Anyway, have a look at this thread: http://www.cadillacforums.com/forums/2008-2013-cadillac-cts-general-discussion/270629-humming-sound-while-driving.html
OP - are you certain that it can't be a wheel bearing causing the problem?

 

[kkuz]

It was time for a brake job, 114K miles on the original pads. Needless to say my wife isn't hard on the brakes

New pads, turned the rotors and replaced the fluid.

First, it is unbelievable to have one pads for 114k, congrats to your wife.
Second, how did they do a pull test for bearings?

 

[roadtrip56]

I didn't ask how they did the pull test. As far as I know there's only one way to do a pull test. For the most part if bearings aren't sloppy they're good so pulling on the wheel (top or bottom) when they're unloaded will show how much play is in the bearings.

I took it out for some more in depth road testing on Sat. The noise starts just over 25mph and gets worse turning left. It's still there turning right, but is quieter than going straight. I can feel the vibration in the gas peddle but not the floorboards, seat, shifter, etc. Hard acceleration and using sport mode transmission don't change anything. With the windows down, there aren't any unusual sounds, whine/grinding/squealing/etc.

Bearing or CV seem possible likely but the sound is all wrong for either. If it did it sitting still I would say power steering pump. The sounds are right for that.

I'll try to get it into the Caddy dealer for a test drive this afternoon.

 

[ksa8907]

Without delving too far in, my guess is either right front wheel bearing or the differential. You mention that you have the base model, so you do not have the limited slip diff?

You can throw money at it or spend the money/time to look it over really closely. If you replace anything I would go for the diff fluid first as it is something that should be replaced anyway.

 

[roadtrip56]

I took it in to my dealer and was able to get a mechanic to do a drive. He said front bearings, probably right. He said that he's had cases where they thought it was 1 side or the other and ended up being the opposite side. Because of the suspension design sometimes it fools them. For that reason the normally do a spin test before they tear it down.

I asked him about the sound being so low where I'm always found higher pitched squealing type sound with bearings. He said that these cars have bearings that aren't a tapered race design so when they fail the sound is different.

Given the price tag the quoted me I think I'll do them myself :canttalk:

 

[kkuz]

This is why I asked you how they did the test for bearings. I recall one time I had similar issue, mechanic said differential, but I found place where they could spin each wheel to ~40-50 mph using portable drive. The noise was very audible in one wheel which was not suspected at all.

 

[roadtrip56]

Yeah, from what the Caddy mechanic told me these bearings do not act like traditional 2 piece bearings. They are sealed and pressed into the hub. The only way to be sure is a spin test, a pull test isn't reliable on these.

I found the parts last night and boy are they proud of them ($$$). You can't get the bearing alone, the hub and bearing is a single part. I'm going to do both sides for preventative measures.

I guess I shouldn't complain since we've had the car for over 6 years and no big dollar repairs.

 

[microfuture]

...bad bearing hasn't happened to me, but thought I saw thread mentions that
Timken was a good alternative.

 

[roadtrip56]

We have a local Chevy dealer who is selling online as well as onsite. Napa, Oreilly and others have these at $250+/- while the dealer has the OE part discounted online at $172. Since they're local I can counter pickup for $3.50/each if I don't want to pay full shipping.

 

[remmyman]

Have you priced the bearing at Rock Auto.com. Usually a lot cheaper than your local parts stores. Although you have to pay shipping there is no sales tax.

 

[roadtrip56]

Next time you're looking for parts check out gmpartsclub.com. They have great prices and they're a dealer so you're getting GM parts. And if you give them your VIN they'll do a fit check just in case you pick the wrong one.

They had the hub assembly $77 cheaper than Napa, O'Reilly or online. Since they're local shipping is fast. I ordered them Monday night and they'll be delivered today (Wed).

 

[roadtrip56]

Followup

Problem fixed, left front bearing.

I thought it would be the right so I did that one Sat, but it wasn't that one. I got another break in the rain on Mon and did the left. My wife is happy with her car again, me too.

 

[tinman]

Had to be. Good on you for gittin' 'er done.