Rear end harmonic noise

[drjeff]

My 2918 with under 2k miles has developed a low harmonic noise from the rear end that starts with the wheels turning and stops when the wheels stop. It is not a squeak, rattle, thump, or grind. It reminds me of rubbing your finger on a glass rim but in a very low range. Anyone else with this type of issue?

 

[proeasy]

Which axle ratio. 3,31 or 3.73. (Tow Package)

All the time or temperature dependent. I would focus on the rear drive unit

 

[drjeff]

All the time. There is not a great deal of temperature variation in Phoenix. Axle 3.31 without tow pkg.

 

[rcompart]

Does it make the noise in reverse? Get louder the faster you drive? Does the noise change when turning?

 

[drjeff]

Noise forward and backward. Don't hear it at road speed but noticeable before stopping and starting to move. No change with turning. The noise does seem to change pitch with increase speed.

 

[Garrett]

You're not talking about the turbo Ecoboost sound are you?

 

[J Ski]

My 2918 with under 2k miles has developed a low harmonic noise from the rear end that starts with the wheels turning and stops when the wheels stop. It is not a squeak, rattle, thump, or grind. It reminds me of rubbing your finger on a glass rim but in a very low range. Anyone else with this type of issue?

Anything you can see like Debris stuck in brake pads, stuck in shroud around the rotor, something cutting into rotor? Any weird looking marks around the rotor?

 

[aggiegrad05]

You're not talking about the turbo Ecoboost sound are you?

That’s what I was thinking. There’s always a little whine from the turbos, although I can’t think of whether it happens in reverse too.

 

[TxBrian]

Make sure you don't have anything in the tire .
My wife picked up a lag bolt a couple weeks ago.

 

[J Ski]

You're not talking about the turbo Ecoboost sound are you?

They wouldn’t be making noise in the rear end

 

[aggiegrad05]

They wouldn’t be making noise in the rear end

My ecoboost whistle sounds like it’s coming from the rear...no question. At least while driving. And the rear passenger side, so just about right where the exhaust pipe is.

 

[J Ski]

They must’ve moved the turbos back about 8’ on the newer models

 

[aggiegrad05]

They must’ve moved the turbos back about 8’ on the newer models

Haha! I know the turbos aren’t back there, I’m just saying when the boost kicks in, at least while driving, the whistle definitely sounds like it’s coming from the back. I’m guessing it’s because of the added sound insulation (maybe only on the plati?) or has something to do with the fake engine noise they pipe in. Honestly I can hear VERY little engine noise at all, even when I get angry with the go-fast pedal.

 

[Artie]

Haha! I know the turbos aren’t back there, I’m just saying when the boost kicks in, at least while driving, the whistle definitely sounds like it’s coming from the back. I’m guessing it’s because of the added sound insulation (maybe only on the plati?) or has something to do with the fake engine noise they pipe in. Honestly I can hear VERY little engine noise at all, even when I get angry with the go-fast pedal.

Same here, I don’t hear much at all after start up. I’ve yet to hear the turbos as well and I’ve gotten in the throttle several times.

 

[J Ski]

Same here, I don’t hear much at all after start up. I’ve yet to hear the turbos as well and I’ve gotten in the throttle several times.

Upgrade that intake system and you’ll hear them

 

[Artie]

Upgrade that intake system and you’ll hear them

I like it quiet and 450hp is plenty for my needs.

 

[Bones]

I purchased my 2018 Expy Platinum Max new and started hearing the humming noise right away while driving. It doesn't do it all of the time and the volume fluctuates in intensity and not reproducible. I tried driving with the sound system off and it didn't make any difference. Then the Expy threw a curve at me; I started it after being off for the night and was in park idling and the humming started and got very loud. It caught me off guard and I didn't think to turn off the engine. After about 10 seconds it stopped. I should also clarify that the humming is coming from the rear and I don't have the tow package.

 

[proeasy]

Electric Fuel Pump?

 

[drjeff]

I have have not had turbos before and are they operating at slow startup speeds? The fuel pump would not make noise only when the wheels are turning I would think.

 

[J Ski]

I have have not had turbos before and are they operating at slow startup speeds? The fuel pump would not make noise only when the wheels are turning I would think.

They don’t kick in until enough pressure is built up