Here's why:
* Differential Operation: The differential allows the rear wheels to rotate at different speeds when cornering. It uses gears, bearings, and lubricants to do this.
* Whine under acceleration: When you accelerate, the gears inside the differential are under increased load and stress. If a bearing is worn or damaged, the increased load causes the metal surfaces to rub, producing a high-pitched whine. A worn pinion gear can also create a similar sound.
* Silence when off gas: When you release the accelerator, the load on the differential decreases, reducing the noise.
Will replacement fix it?
Likely, yes. If the noise is indeed from a worn differential bearing or pinion gear, replacing the faulty component(s) should resolve the issue. However, there's a small chance the problem could be something else, like:
* Worn differential carrier bearings: These support the entire differential assembly.
* Low differential fluid: While less likely to cause a high-pitched whine, low fluid can certainly contribute to noise and premature wear.
* Other drivetrain issues: Though less probable given your description, other parts in the drivetrain could contribute to a similar sound. A thorough inspection is necessary.
What you should do:
1. Check the differential fluid: This is the easiest and cheapest first step. Check the fluid level and condition. If it's low, dirty, or smells burnt, you'll likely need a fluid change (and perhaps more). This won't fix a worn bearing, but it might help diagnose the problem or prevent further damage.
2. Get a professional inspection: Take your Tahoe to a trusted mechanic specializing in drivetrain components. They can pinpoint the exact source of the noise and provide an accurate diagnosis and repair quote. Don't drive the vehicle extensively with the noise, as it could cause further damage and potentially lead to a catastrophic failure.
Ignoring this problem could lead to more significant damage, potential loss of control, and a much more expensive repair later on. Professional diagnosis is crucial.
