I have to say this forum's been great a bout diagnosing issues on my car and providing the necessary "DIY" to get things done.
My car is an '02, 1.8T with 118,000 on it. I have a loud humming noise coming form the rear that's definitely not normal. Here's everything I know and everything I've done:
- The noise resonates from 35mph and up and is definitely coming from the rear. On the highway, its starting to overtake my radio at normal levels.
- I folded the rear seats down yesterday and you can hear the noise loud as day! I had someone with me yesterday and they swore it was coming from the center of the car.
- I changed the fuel filter, the other day. No resolution.
- Power delivery seems fine, which leads me to believe its NOT the fuel pump, but I'm not ruling this out. Is it possible to have a pump make hummjing noise, but function fine???
- The rotors and pads were swapped out 5k-10k ago. (I'm not ruling this out yet... I had one of these brake pads separate from its backing plate (it was inside and I didn't realize it until I was replacing them with the same pads).
- The differential fluid was swapped out maybe 10k ago with Motul 300. I just noticed the noise a couple of weeks ago and now its progressively getting worse. (Maybe I screwed up the fluid swap... but I'm pretty sure its one drain plug and one fill plug for the rear???).
- I put the car on ramps (on a hill so the car was still level) and checked the differential fluid this morning... full.
- Inspected the CV joints... none of the boots are have tears or anything and they all seem like there in good shape
- Cornering, the sound remains constant. Based on this, I'm ruling out wheel bearings, but I could be wrong. Yes, I drove down the street and jerked right and then left... no change... car handles likes its on rails... and the humming noise is constant.
- Checked the tires for cupping... nothing there. Their Goodyear Eagle GT's with maybe 15k on them.
- Wheels were recently powdercoated and the tires of course were all rebalanced (I'm not sure this sound is indicative of an unbalanced wheel though... I'm thinking no).
I searched on here and there's been a myriad of answers thrown in, all of them making perfect sense and having perfect relevance. My problem is, there's too many potentials. Looking for advice on how to diagnose the problem. Here are some of the potential issues I've heard...
- Fuel pump
- CV Joints
- Pinion Bearing (no idea what this is)
- Wheel bearings
- Cupped tires
Please help... and THANKS IN ADVANCE.