Skip the auto shop - Our mechanics make house calls

Q: Loud metal sounding noise at 20 mph then again at 40-50 mph.

asked by on

As I drive there is a metallic sounding noise at 20-30 mph then at 40-50 mph. I notice if I drive faster then I don't hear it but if I slowly progress it can get quite loud. No one can tell me what it is. Now an engine light came on when I filled up the tank. Doesn't seem to bog when the noise is present but it is getting louder. Any help would be appreciated. Thank-you, Steve

My car has 64000 miles.
My car has an automatic transmission.

It’s great that you are trying to be your own detective! This information is very helpful for a mechanic who isn’t there to hear the noise. My first thought after seeing the specific speeds was that this noise is transmission related. The Check Engine Light could be related to your problem, and filling the tank was just a coincidence. Or, the Check Engine Light is related to filling the tank and is not related to the noise. Have the computer scanned by mechanic to see what the code is.

I found a technical bulletin for your car about a shudder, or a exhaust moan at 40 to 45 mph. I’ve heard noises like this before. It’s a resonating noise that can fill the cabin and drown out everything else. It happens at low engine speed, and light throttle application. It is related to the "transmission converter clutch" or TCC. If this sounds like the problem you are having, the fix is an engine computer (PCM) reprogram. It modifies the shifting strategy so it does not "lug" the engine. Your transmission fluid may need to be flushed as well if the reprogram does not entirely repair it. The bulletin number is 06-07-30-30A. Only a Cadillac or GM dealer can reprogram the PCM. If you have an extended warranty, this should be covered. If not, you will have to pay for it, so make a few calls as prices can vary.

If you find that this is not the source of the noise, your best option is to have a mechanic ride in the car and inspect the car noise. If you would like to have an accurate diagnosis before taking the car to the dealer, consider YourMechanic, as a certified mechanic can come to your home or office to determine what repairs are needed.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Loud metal sounding noise at 20 mph then again at 40-50 mph.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: How much would the labor cost be to change both headlights not just the bulb, and to Swap out a mesh grille also?

To replace both headlights on this vehicle would take about 3 hours. If you desire this service, please use YourMechanic's headlamp service page to schedule. Although the latter page is for the bulb only, the charges will be adjusted once...

Q: 2006 malibu not starting, not turning over can hear relay clicking. First time removed battery cables retried car started then ag

What you are describing sounds like a faulty starter solenoid. A faulty starter solenoid will generally produce a clicking sound when turning the key. The starter solenoid is located on the starter and has internal electrical contacts that transmit electricity...

Q: 1993 cadillac seville motor mounts 4.9 engine

Hi there. On most GM V-8's there are four total engine mounts and two transmission mounts. If you'd like to receive a price estimate to have your engine mounts replaced, please click this link to be forwarded to the engine...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...