Hey guys, I picked up my 2005 King Ranch back in July, and it has a "howl" that develops around 50mph. I figure it might be the rear end, and have done some reading and learned that there is a problem with the bearings going in the rear end. If it isn't that, I figure it is the transmission.

I have been doing a little playing around while driving trying to manipulate the sound and diagnose whether it is coming from the transmission or the rear end. First of all, the noise only occurs at highway speeds but varies on volume and pitch. Some days it is barely noticeable, while others it is quite loud.

I have noticed that it depends on load. It will get louder when it is windy, or going up an incline and the truck is working harder. Today, as I was coming up a valley hill, the pitch increased significantly, and stayed quite a bit higher than it usually does for quite sometime. I used this as an opportunity to try and diagnose where it was coming from.

If I am cruising at 70 and let off the gas, the sound will go away. If I continue to keep my foot off the gas and let the truck decelerate, the sound will come back and will become less noticeable, both in pitch and volume, as the truck slows to about 50, then the sound disappears.

I sped up from about 60 to 85 to see what it would do, the sound stays and increases in pitch as speed increases.

If I am cruising at 70 and turn overdrive off, RPM's obviously goes up, however the pitch of the noise stays the same.

If I am cruising at 70 and step on it so the tranny downshifts into 3rd, the pitch stays the same.

So, from this I have determined that the noise is speed dependent rather than RPM dependent, so that leads me to believe that it is not the transmission.

I am just a little confused because I have not heard a bearing noise similar to this before. The change in pitch when RPM's and speed stay generally the same, but load increases really gets me.

I was just wondering if there is a surefire way to perform a proper diagnosis and try to pinpoint the problem.

I should also add, I have never let someone else work on my vehicle and don't plan to start now, so I am not interested in taking it to the dealership and throwing money at it until the problem is fixed. I would just like a way to confirm which component is failing so I have a better idea where to start.

Thanks,
Steve

 

Probably your bearings in the rear end. If the noise just started you have begun to burn up a bearing. I would suggest having it done by a Ford Tech. Mainly because if not done right the noise will never go away. There are some very specific write ups on here about this and how to's . But there are some people on here that have had the noise for a very long time and no issues...

The change in the pitch is just going to be your tranny changing the load on the rear end.

 

Doms ..... Did you ever check the rear end lube for proper amount in all that time?

 

I have had a couple of front wheel bearings go out on mine and then develpoed a roaring noise that would increase and decrease with speed or sometimes on different roads. I suspected a carrier bearing. Then, I changed out my tires and wheels and all noise disappeared. Turned out to be the tires had begun to cup and were making the noise.

 

Tbear, no I have not checked the rear end fluid level. I have been meaning too, but have yet to get around to it. There are no signs of leakage from the rear differential or the axel seals. I will check the fluid level tonight. I should just go ahead and change it. What are you guys running for lubrication/ additives in the rear end?

Tires are new, so that is not it. There is some road noise because of the aggressive tread, but this is something else.

I did not consider the carrier bearing...

 

Awwww...I thought this thread was gonna be about Nitto Mud Grapplers going down the highway

Darn you misleading thread titles.

 

Well, it was just a thought since you bought the truck in July 2011 and it''s a 2005 model truck. It might not be leaking because the seals are good .... or maybe because it's near empty.
It's not unusual for the seller to steam or presure wash underneath.

I'ld run what Ford specs in the book .... which depends on wheather you have TL or not?

From my '07's owner's book, pgs 354-356 dealing with 8.8 / 9.75 axles ....

 

I wonder what fixed the issue. I hate when we don't hear back...

 

Yeah, especially since he hasn't been back since the day after the first post.