Front drivetrain noise

[Jon Lane]

Car recently started a noise across the front of the cabin, under the dash. Noise is centered at 40mph, is not related to gear or clutch position, happens in all gears, and sounds like an intermittent howling/grind that comes and goes.

• Not throttle position related
• Happens in all gears
• Not clutch position related
• Seems to be about on the axis of your feet, all the way across the front of the cabin
• Centered on about 40mph - cannot hear it below this speed and road noise may mask it above this speed. Can only hear it with the windows up.

Ideas?

 

[Gstclipse69]

I would check the short shaft bracket on the driver side axle that bolts to the back of the block. It could be loose, and just give the axles a once over.

 

[Jon Lane]

Thanks. Does the left side axle plug into the short shaft or are they one unit?

The more I hear this the more it sounds like this bearing.

 

[jtmcinder]

Given the location, I'd be looking at the carrier bearings on the prop-shaft and the transfer case.

I'm almost tempted to ask if the noise is also "centered" on 80 mph, to see if this is a resonate-frequency thing, but that could be very dangerous, especially if this is a transfer case giving you a little warning before locking up.

 

[Jon Lane]

Given the location, I'd be looking at the carrier bearings on the prop-shaft and the transfer case.

Both carrier bearings were replaced with new ones just days before this problem, as was the transmission and transfer case. The T-case was used but reshimmed and re-sealed.

The axles have about 80k on them and are remans of unknown quality.

I'm almost tempted to ask if the noise is also "centered" on 80 mph, to see if this is a resonate-frequency thing, but that could be very dangerous, especially if this is a transfer case giving you a little warning before locking up.

I have the original T-case (175k miles) and think I'll just get it rebuilt.

I've driven the car another 15 miles around town. I can define this noise as a grinding now. Still relatively soft and still intermittent in that it's never a constant amplitude, but it's sounding a lot like something's rotating loose and/or dry in the front driveline, about foot-level all the way across the cabin. Very hard to localize, which is why I started the topic here.

Thanks, Toby.

 

[Jon Lane]

Solved: Front wheel bearings.