08 EX-L - Droning/Humming noise around 2k RPM

smashedbeard

Like most people have described with these vans, mine (or should I say, my wife's) is making a pretty loud drone/humming noise between 2-2.5k rpms. As others have described before, its almost like a ram air intake sound. This van is sitting just under 139k, we've had it for 3 years next month and have had no other issues out of it.

Here is how mine is different from others that I have read about on here. It only happens in gear, moving or not. If I'm going down the road and its happening, I can pop it into N and it goes away completely. This is making me think it isn't the wheel bearing issue that others have had with the same sound, and something on the tranny/torque converter end.

Also, it seems to almost go away after the car is warmed up, not 100%, but I'd say 90%. It doesn't really sound like a heat shield wiggling around either. I will try to make a video of it tonight if that will help, but like other videos posted of the issue, it seems hard to pick up the sound.

I'm planning on spending some time on it Saturday, so I'm trying to get plan together on where to start and what to be looking for. Any help will be greatly appreciated.

Mr_Shiftright

Why don't you try this? Put it in Park and then rev the engine to the approximate RPM level of the "drone" and hold it there and see if the noise shows up.

smashedbeard

Mr_Shiftright said:

Why don't you try this? Put it in Park and then rev the engine to the approximate RPM level of the "drone" and hold it there and see if the noise shows up.

Guess I should have included that, I tried that last weekend, with my wife in the drive seat and with my ear in the engine bay. That's when I determined it only happens when driving. Nothing happened in park, but as soon as I drove it down the street it was present.

Mr_Shiftright

Does it go away on deceleration?

Does it increase or decrease in frequency as you increase or decrease speed?

smashedbeard

I will confirm, but if I remember correctly it completely goes away as soon as your foot is off the gas.

The frequency does not change with speed, but it goes away as soon as you hit about 3k rpm

Mr_Shiftright

Finding dynamic vibrations in a vehicle can be very tricky. From all you say, I'm leaning towards this being an exhaust system resonance--maybe a loose clamp or even squishy motor or transmission mounts.

Tire balance issues wouldn't improve as the vehicle warms up.
Wheel bearing noise would increase and decrease with speed

smashedbeard

Mr_Shiftright said:

Finding dynamic vibrations in a vehicle can be very tricky. From all you say, I'm leaning towards this being an exhaust system resonance--maybe a loose clamp or even squishy motor or transmission mounts.

Tire balance issues wouldn't improve as the vehicle warms up.
Wheel bearing noise would increase and decrease with speed

Thanks Mr_Shiftright

I'll get the van up off the ground this weekend and check all the connections from the exhaust manifold back.

I saw a comment on another thread about a flexible connection between 2 of the pieces are the Cat being the issue, hopefully mine ends up being similar.

Mr_Shiftright

Catalytics can also fall apart internally (the ceramic part) and rattle around in there. So you might bang on it and listen for loose pieces.

smashedbeard

Just got done crawling around the thing a little. As far as I can tell the Catalytic is fine, I banged on it a few times with my palm and a rubber mallet and it sounded solid.

I checked all the exhaust mounts and connections and they seemed fine to me. I also took a look at the motor mounts and as far as I can tell they also look fine. With one exception, the front one caught my eye. It kind of looks like it is compressed, which is on the driver side of the mount. This might be normal, but it looked out of place to me.

smashedbeard

I was able to pick up the noise decently well, Although it wasn't as loud as it sometimes is today.

https://youtu.be/1GD6d4uY5s8

smashedbeard

Well, in case anyone is still following along, I may have found the culprit. Right behind the flex piece on the exhaust A pipe, the weld had completely broken apart while I was driving it last night.

I checked in a weekend or two ago and don't remember seeing any noticeable breaks, but I guess there could have been a hole or tear that wasn't visible.

Looking to see if there is a way I can pull it back together and weld it back together, but if not it looks like I can get the A pipe for about $100.

Mr_Shiftright

Depending on how bad the break is, and if rust involved, a good muffler shop can weld that up---or perhaps replace the pipe for not much more than the labor to weld it up.

Edtwin88

Did a weld or replacement fix that noise? I have the same problem and I'm thinking rear bearing but hoping its this pipe situation.. thanks for positing..

Cheers