C420sailor
Explorer Addict
- Joined
- July 29, 2008
- Messages
- 2,512
- Reaction score
- 2,081
- City, State
- Long Island, NY
- Year, Model & Trim Level
- 98 XLT SOHC, 99 EB 5.0L
Vehicle History: 98 Explorer XLT, SOHC, 4x4, 191k miles. Original engine, rebuilt trans. Original front differential, transfer case, front driveshaft/joints, CV axles. All front suspension components are fairly new, in good shape, greased, no play. LF wheel bearing assy replaced today (Moog), RF wheel bearing assy replaced at 120k (Timken).
Complaint: Low pitch pulsing rumble that varies with vehicle speed. Almost sounds like tire noise, but lower pitch, more 'solid', and more sinister. First audible around 27mph, resonates most between 30-40, is overtaken by wind noise over 55-60mph. Pulsing is 8 Hz at 40mph, which corresponds to wheel rotation rate. Turning (fast/slow, small/large radius) does not change the sound. No clicks, bangs, etc. Sound seems to be coming from just left of centerline, forward of the passenger compartment, in the vicinity of the pumpkin (if I had to guess). No gear whirring or whining, except in 4x4 HI/LO. No pulsing in the brake pedal or steering wheel. Sound is independent of acceleration or deceleration.
"Corrective" Actions: Badly worn front tires (severe camber wear) removed. Rear tires (50k) rotated forward. New tires (<800mi now) installed on rear. Front end aligned, all wheels balanced. LF wheel bearing replaced today (my gut reaction was a wheel bearing). Differential fluid topped off (has slow leak, passenger side axle output). Swapped LF and RF tires---sound did not move/change.
It may be my mind, but it seemed like the noise got slightly quieter after topping off the diff. I don't think it's the CV joints, as those usually make clicking/banging/popping noises, especially in turns, when they're going out. The fact that the pulsing coincides with wheel rpm makes me fairly confident it isn't a driveshaft u-joint or pinion bearing.
Thoughts? Thanks guys!
Complaint: Low pitch pulsing rumble that varies with vehicle speed. Almost sounds like tire noise, but lower pitch, more 'solid', and more sinister. First audible around 27mph, resonates most between 30-40, is overtaken by wind noise over 55-60mph. Pulsing is 8 Hz at 40mph, which corresponds to wheel rotation rate. Turning (fast/slow, small/large radius) does not change the sound. No clicks, bangs, etc. Sound seems to be coming from just left of centerline, forward of the passenger compartment, in the vicinity of the pumpkin (if I had to guess). No gear whirring or whining, except in 4x4 HI/LO. No pulsing in the brake pedal or steering wheel. Sound is independent of acceleration or deceleration.
"Corrective" Actions: Badly worn front tires (severe camber wear) removed. Rear tires (50k) rotated forward. New tires (<800mi now) installed on rear. Front end aligned, all wheels balanced. LF wheel bearing replaced today (my gut reaction was a wheel bearing). Differential fluid topped off (has slow leak, passenger side axle output). Swapped LF and RF tires---sound did not move/change.
It may be my mind, but it seemed like the noise got slightly quieter after topping off the diff. I don't think it's the CV joints, as those usually make clicking/banging/popping noises, especially in turns, when they're going out. The fact that the pulsing coincides with wheel rpm makes me fairly confident it isn't a driveshaft u-joint or pinion bearing.
Thoughts? Thanks guys!
