Howling or whining noise after 30mph only accerlating.. Other issues??

[Nolanxce]

I have a 2008 ford explorer xlt with 70k miles.

I have noticed that when im driving, after it kicks into 4th gear or after about 30mph (depending on how hard i am on the gas) i start yo hear a howl/whine noise. I can hear inside the truck. If i let go off the gas, it goes away. If i slightly push the gas in and out you can hear it and then go away. It is perfectly synced.

I have also replaced the serpentine belt twice this month and it seems to be chirping again already. I replaced tensioner also.

These issues related??? Truck drives perfect but the noises are killing me!!!!!

 

[Tech By Trade]

little vacuum valve on the firewall that fails. fits the bill. have a search.

 

[Nolanxce]

Okay I will check for it. Do a few searches.

Do you know the specific vacuum line I am looking for?

Thank you in advanced for your input.

 

[berny13]

It's called the A/C vacuum check valve. Have similar issue and replaced mine with little success. See this post for an idea:

http://www.explorerforum.com/forums/showthread.php?t=267635

Berny

 

[Nolanxce]

Okay i will check into this. I dont really think it is a hiss sound. I want to say it sounds more like differential but after 70k miles. And what makes less sense is that it happens on accel, my old explorer did that when i released the gas and it had a bad diff. Strange issue..

 

[BLUHITZ]

I have an explorer and have the same symptom. It seems to be only when changing from 3rd to 4th. But when it gets on gear it seams to be find. I'm thinking it could be the servo bore leaking pressure.

 

[Nolanxce]

Yeah mine is about 4th gear also but seems to have the symtoms through 4th gear. On acceleration i hear the sound.. After i get passed 50mph and it kicks into 5th, no more sound.. This issue should really be addressed. My buddy has a '07 that does it and no mechanic has been able to pin point the problem and i am pretty well mechanically inclined myself. Dealer doesnt seem to have time for **** lol

 

[Nolanxce]

found the solution...

Rear differential - bad pinion bearing

figures.. Thank goodness for warranties.

Thanks all!