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Loud Roaring Sound

I have a 1999 Mercury Mountaineer. Every time I reach a speed of 35 MPH or higher I hear a constant noise which sounds like an airplane taxi-ing down the runway for takeoff. The sound is very loud in the front on the driver’s side, but you can also hear it when sitting in the passenger side although not as loud. It has been suggested that it might be a transmission problem. Does anyone have a clue as to what it might be? If it is a transmission problem will it be costly?

Could it be a transmission problem?

However, it could also be a bad wheel bearing, or it could be noise from your tires. As tire treads wear, many of them become much noisier than they were previously. Also, if a tire’s belts slip out of place, that situation can produce some new noises.

The noise could also be from a differential that is low on oil. When was the last time that the diff oil was checked by your mechanic?

To return to the issue of the transmission, can you tell us when the trans fluid (and filter) were last changed? If the trans fluid had not been changed every 3 years/30k miles (whichever comes first), then you could be having the beginnings of transmission problems. We don’t know the odometer mileage of this vehicle, but on the basis of elapsed time, the trans fluid should have been changed 3 times already. When trans fluid is not changed on this type of schedule, trans failure is possible any time after 90k-100k miles.

Anyway, since a wheel bearing problem is a safety-related issue, I would suggest that you get this vehicle to a competent independent mechanic (NOT to any kind of chain operation, such as Midas, Meineke, Monro, Sears, Pep Boys, AAMCO, etc.) soon. And, if the noise is from a defective tire, that is also a safety-related issue.

Check and see if there’s a radiator fan clutch on the engine instead of an electric fan. If it has a fan clutch, the clutch may be faulty.

To determine if the fan clutch is the problem, with the engune cold, spin the fan by hand. It should rotate a few times. If it doesn’t rotate freely, the fan clutch is engaged causing the roaring noise.


I had both wheel hubs replaced two years ago approx 87K miles. The left wheel was replaced again several months later due to a defect. They just replaced the right wheel hub again last week - I thought that was the problem. I have driven 8,000 since the wheel hubs were originally replaced two years ago. I did ask if the tires may be causing the problem. My tires were replaced in Feb 2002 dues to Firestone recall - now have Michelin. Odometer is at approx. 95k miles. The last transmission service (flush & fill) was April 09. Diff fluids were done at approx 84k miles - That was May of 08.

Thanks for the input. I will certainly mention that. I need as much input as I can get before I bring it back in.

I would bet it is the fan clutch, if it has one.

Ok now I am getting upset. I just brought it back into my mechanic (GoodYear) and I pointed out all those possibilities to them. I just got a call from them and now they think it is the left wheel bearing assembly. As I stated previously, they were initially replaced two years (Oct 2007)ago at 87k miles. Then several months later they had to again replace the left wheel hub (not charged for parts or labor). Just last week when I brought it in they said the right wheel hub needed to be replaced (not charged for parts, but for labor). Now today, they say its the left wheel hub assembly (shouldn’t be a charge for parts, but labor only). I have only driven 8K miles since the initial hub wheel bearing assemblies were replaced. What am I supposed to think, and can anyone give me advice on this? Is this usual for these assemblies?. What action should I take or can I take? I appreciate your comments

Please see second response posted today. Should I take the car to the dealer for repair? What could be going on here? Any suggestions as to what I should do?