2002 Q45 humming noise from rear

[ahmed_wasim]

2002 Q45 with 98k miles (157k km) on it.

I can hear a humming noise from rear while driving. Its pretty loud. Doesn't seem like a fuel pump as there is no noise when car is at a stop.

On my last oil change the mechanic didn't put the bottom car cover properly and I can see its hanging from one end.

But the noise I hear is from the back of the car. Any ideas what it can be?

[paranoidjack]

2002 Q45 with 98k miles (157k km) on it.

I can hear a humming noise from rear while driving. Its pretty loud. Doesn't seem like a fuel pump as there is no noise when car is at a stop.

On my last oil change the mechanic didn't put the bottom car cover properly and I can see its hanging from one end.

But the noise I hear is from the back of the car. Any ideas what it can be?

Little more info required....

sounds rises with speed? Certain rpm/speed is it more pronounced? At idle? Engine off? Bumpy Roads/smooth roads? When braking, accelerating, coasting?

[StarPD]

2002 Q45 with 98k miles (157k km) on it.

I can hear a humming noise from rear while driving. Its pretty loud. Doesn't seem like a fuel pump as there is no noise when car is at a stop.

On my last oil change the mechanic didn't put the bottom car cover properly and I can see its hanging from one end.

But the noise I hear is from the back of the car. Any ideas what it can be?

I have a 2005 Q45 w/ 30k miles that has a howl or hum from the rear too. It's fairly high pitched. It's load sensitive, and occurs from around 50 to 70 MPH, comes and goes as car goes over rises in road on cruise control.

It's not real loud, but is annoying. Dealer can't hear it very well, but I notice it from time to time, worse sometimes than others.I'm thinking differential.

Any ideas from anyone?

[ahmed_wasim]

Its directly proportional to speed, the more the speed the more the noise. No noise if the car is parked. I tried to rev the parked car but there is no noise at all.Road surface doesn't make any difference but you can hear it better on smooth roads.

[Skibane]

On my last oil change the mechanic didn't put the bottom car cover properly

At the risk of stating the obvious, did he also change the rear end oil (and forget to install fresh oil)?

[ahmed_wasim]

I put the car in neutral while driving at 40 mph and let it come to a complete stop. The noise was there and decreased as the car slowed. There is no noise when the car is stopped.

The dealer did the oil change and tire balancing and rotation. This problem started after I picked it up from the dealer.

Can the noise be caused by the undercover not intalled properly.

[ahmed_wasim]

I took the car to the dealer and rear left and right bearings are shot. They quoted me 1100 bucks to replace them. Is it a good idea to look for the used ones?

[Skibane]

I took the car to the dealer and rear left and right bearings are shot.

Are you talking about the wheel bearings, or the side bearings inside the differential?

Does the mechanic who originally changed your oil work at this dealership?

Are you SURE there was oil in the differential before you had the dealership look at it?

[ahmed_wasim]

Its wheel bearings for both wheels. Funny things is there was no noise before I took it for tire rotation and balancing last week.

[Q451990]

I think I would get a second opinion.

Heath

[ahmed_wasim]

I took it to an independant shop and they can install the aftermarket bearings at half the price. Should I install the aftermarket ones or should I stick to OEM?

[maxnix]

After market only if they are the same grade as OEM.

[Q45tech]

http://www.car-stuff.com/mmpar....html

[ahmed_wasim]

Thanks, that a lot of price difference. There dealer here is asking for $350 (parts only) for one side.

[StarPD]

Thanks, that a lot of price difference. There dealer here is asking for $350 (parts only) for one side.

Sounds like your dealer is ripping you off. Try another dealer, and get a price to install bearings you provide, then get the best Timken's from the source Q45 Tech provided. Get a price from the independent shop to install your bearings too, then compare prices. Installing wheel bearings shouldn't require the same expertise that other Q45 work does. Ask Q45 Tech if he concurs with this. If he does, and the shop that gave you a lower price is a known reputable one, have them install bearings you supply, and save a bundle and still get top quality parts that will last you.

I find it strange that your wheel bearings are shot though. That doesn't seem to be a common problem with Q45s, especially both of them at the same time. I wonder if there isn't a reason they went South on you. Did the car get soaked in standing water at some time, maybe before you got it? You may want to follow up on this. If that's the case, there are going to be other issues you'll have to deal with at some time in the near future. Front wheel bearings, U-joints, diff, suspension, etc, maybe even trans. I'd check it out before you sink any money into this car. Then if it checks out okay, replace the rear wheel bearings

What do the others here think?