Hello all! new to the forum and was hoping to tap into the wisdom stream. I have a 2007 Endeavor (base model) AWD with 55K miles. Just bought the beast and after 2 days started noticing a faint-but-consistent shrill whine that increases in pitch as the car (not rpms) increases. It was best described as the metallic "singing" sound of jet taxiing down a runaway, but obviously not nearly as loud.

I can tell you what it's NOT:
NOT radio noise (radio off)
NOT a wheel bearing (no change on cornering)
NOT wind noise
NOT the prop -shaft (just replaced by Mits dealer)
NOT the transfer case (just replaced...)

DETAILS: The shrill whistling noise starts to fade in at 47 mph ONLY WHILE EITHER MAINTAINING SPEED or UNDER SLIGHT LOAD, then gets loudest at 50-52, then fades out at around 57 mph. It goes way completely if you let off the gas. It's loudest with just enough gas pedal to maintain speed. It sounds like it's coming from the engine compartment, just in front of the glove box, or by the right front wheel, but there's no telling where it could be travelling from.

My local wrench told me that it sounded like the "ring-and-pinion" going bad in the front differential, causing the plates to separate, therefore allowing the plate harmonics to "sing" when they reach the right speed and frequency. The MITS tech told me that the Endeavor doesn't have an actual front differential, per se, nor would it be the problem that the 04-05 models had, where the rear differentail went bad.

It just spend better part of 3 weeks at area dealer, until they finally told that it's a "normal sound, albeit a bit louder!" If it was so normal, why did they replace all the above expensive stuff (under warranty) and waste my time?

I have no idea where else to look, and I'm running out of warranty time rapidly. Any direction would be greatly appreciated!!!

Thanks in advance!
Fiver64

 

its probably normal.
you have a massive amount of geartrain in that car... and although you dont have a "ring and pinion" as a traditional car, you do have 3 of them.
and some light geartrain noise is TOTALLY normal on any a.w.d car.

 

Thanks for the input. Much appreciated. Just have never heard anything quite as loud or as annoying in alomst 30 years of driving many, many different vehicles. Can't say I'm as familiar with AWD, so it's throwing me for a bit of a loop!

 

Its not normal. If the noise is one that starts around 30 mph and gradually gets louder it is your propeller shaft. It is a pretty common repair on Endeavors (usually around higher mileage ones though). The propeller shaft is the 3-piece drive shaft from the trans to the rear differential. I had to replace the one on my wifes car just a few months ago as hers acquired the familiar metallic squeal noise. It kinda sounds like a squealing drive belt. The dealership quoted me $800+ for a new one as you have to buy the whole assembly but I did some searching and found one from a used parts distributor for $250 with 30k miles on it. But if yours is still under warranty i would take it in and have them replace your driveshaft.

 

Guess I didn't read through your whole post before replying. Lol... If your prop shaft has already been replaced then maybe just recheck your fluids? But a metallic noise isn't normal on any car, AWD or not.

 

all mitsus, especially AWD ones, DO make a massive amount of gear noise. it is totally normal, more than likely.