Loud humming noise at 40 - 60 mph
05-23-2011, 12:03 AM
#1
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Loud humming noise at 40 - 60 mph
Hello all,
I have a problem with my 2002 A6 3.0. At speeds between 40 ~ 60 mph I hear pretty loud humming noise coming from somewhere. The engine shows about 2000 rpms. I tested the car at stop and neutral, and 2000 rpms. There is no humming noise. I suspect transmission. Is this a sign the transmission is about to die? I have never changed the fluid in the transmission, and the car is at 158k right now.
Please advise. Thanks.
I have a problem with my 2002 A6 3.0. At speeds between 40 ~ 60 mph I hear pretty loud humming noise coming from somewhere. The engine shows about 2000 rpms. I tested the car at stop and neutral, and 2000 rpms. There is no humming noise. I suspect transmission. Is this a sign the transmission is about to die? I have never changed the fluid in the transmission, and the car is at 158k right now.
Please advise. Thanks.
05-23-2011, 04:58 AM
#2
Tough to say...I would try to open your windows and determine if it is coming from a specific wheel, if possible. If you can isolate the sound, pull the wheel and inspect brakes, cv joint boots, etc.
This could be as simple as a rock caught in the rim, a bent brake rotor shield, bad brakes, bad CV joint, loud tires that have worn down, etc. Having the engine in neutral will disengage the transmission, but it also stops the tires from spinning.
It may have nothing to do with the RPMs of the engine - but the speed at which you are going, which you stated was between 40-60.
Also, it's time to change that fluid (about 50-100K miles ago). Change the fluid and filter. Many will say that changing the fluid after this long will kill the transmission, but this is nonsense caused by people who wait until they have failing transmissions before they change fluid. The logic is, "I went 150,000 without changing the fluid and never had a problem. Then I changed the fluid and the transmission failed 5,000 miles later."
Why'd you suddenly change the fluid after 150,000 miles when you never did it before? Because there was a problem....
This could be as simple as a rock caught in the rim, a bent brake rotor shield, bad brakes, bad CV joint, loud tires that have worn down, etc. Having the engine in neutral will disengage the transmission, but it also stops the tires from spinning.
It may have nothing to do with the RPMs of the engine - but the speed at which you are going, which you stated was between 40-60.
Also, it's time to change that fluid (about 50-100K miles ago). Change the fluid and filter. Many will say that changing the fluid after this long will kill the transmission, but this is nonsense caused by people who wait until they have failing transmissions before they change fluid. The logic is, "I went 150,000 without changing the fluid and never had a problem. Then I changed the fluid and the transmission failed 5,000 miles later."
Why'd you suddenly change the fluid after 150,000 miles when you never did it before? Because there was a problem....
Last edited by jseklund; 05-23-2011 at 05:01 AM.
05-23-2011, 04:29 PM
#4
This is going to be a painful question, but it's an important one...what other maintenance has been ignored? Not saying it's your fault, a lot of Audi owners seem to be unaware of maintenance intervals...but the question needs to be addressed. It could be outer CV joints, tires, wheel bearings, carrier bearing, differentials, transmission...
What service has been performed on the car, since 50k miles?
What service has been performed on the car, since 50k miles?
05-23-2011, 07:52 PM
#5
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Thanks for all the suggestions. I think I found the problem. The noise comes from the front wheel bearings. This is messed up, because I changed them about 1 year ago. I installed these cheap ones that came in a kit. Once again, I will never buy any replacement parts in a kit. It's better to spend little more and buy original parts.
In terms of maintenance intervals, I fix my car myself. So far I have replaced:
1. Timing belt and all the accessories (twice). First time I bought timing belt kit, cheap. In a less than a year water pump broke. Almost lost the engine, as the timing belt almost slipped of the rollers. Also, serpentine belt cracked along the surface. I bought original parts, Bosh water pump and so far so good. 3 years and still running.
2. Power steering pump, as the first died.
3. Water temperature sensor and thermostat.
4. Seals on the rear coolant pipe, that connects two engine banks. Coolant was leaking.
5. CV joints
6. Wheel bearings. Front is messed up after a year. Rear ones I bought original, as aftermarket did not fit right.
7. A complete set of front control arms.
8. All ignition coils packs.
9. Flushed brake fluid and replaced seals on the pistons.
10. Brake booster pump (3 times, as it always breaks)
11. All vacuum lines.
I was going to replace breather tube with aftermarket one. The place I bought it from said the tube would fit with no problem. It does not fit at all. Completely different part. I'm going to buy original one.
I think that's all I've done to the car. Maybe I skipped something.
In terms of maintenance intervals, I fix my car myself. So far I have replaced:
1. Timing belt and all the accessories (twice). First time I bought timing belt kit, cheap. In a less than a year water pump broke. Almost lost the engine, as the timing belt almost slipped of the rollers. Also, serpentine belt cracked along the surface. I bought original parts, Bosh water pump and so far so good. 3 years and still running.
2. Power steering pump, as the first died.
3. Water temperature sensor and thermostat.
4. Seals on the rear coolant pipe, that connects two engine banks. Coolant was leaking.
5. CV joints
6. Wheel bearings. Front is messed up after a year. Rear ones I bought original, as aftermarket did not fit right.
7. A complete set of front control arms.
8. All ignition coils packs.
9. Flushed brake fluid and replaced seals on the pistons.
10. Brake booster pump (3 times, as it always breaks)
11. All vacuum lines.
I was going to replace breather tube with aftermarket one. The place I bought it from said the tube would fit with no problem. It does not fit at all. Completely different part. I'm going to buy original one.
I think that's all I've done to the car. Maybe I skipped something.
05-24-2011, 08:41 AM
#7
Good to see someone taking care of their car!
I agree, OEM parts are almost always better quality. Note there's a Chinese-origin brand called "OEM", that is not the same as "Original Equipment Manufacturer", which is what the acronym represents. "OEM Brand" is cheap junk.
What water pump kit did you use? I'm about to replace mine, and with eight years on the original, I'm leaning heavily toward OEM for the critical parts.
Definitely swap the xmission and diff fluid...it's past time. P/S fluid is unrelated to the current issue, but...hey, while you're at it
...
How did you diagnose that it was most likely a wheel bearing, vs an outer CV joint?
I agree, OEM parts are almost always better quality. Note there's a Chinese-origin brand called "OEM", that is not the same as "Original Equipment Manufacturer", which is what the acronym represents. "OEM Brand" is cheap junk.
What water pump kit did you use? I'm about to replace mine, and with eight years on the original, I'm leaning heavily toward OEM for the critical parts.
Definitely swap the xmission and diff fluid...it's past time. P/S fluid is unrelated to the current issue, but...hey, while you're at it
...How did you diagnose that it was most likely a wheel bearing, vs an outer CV joint?
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