BillLee

2004 F-150 Lariat 2wh drive 5.4 Triton 100k miles

Service done regularly at 5k interval at local Ford dealer.

Diagnosed in January with a pinion seal leak. Watched it until June and then had them repair. Drove the truck just a few miles and then parked it while we were gone for a month in the RV.

Upon returning home, drove the truck into town. When using compression to slow (e.g., switch the transmission out of O/D) I get a very pronounced whine/vibration that to my ears is coming from the rear end. Had NEVER done that before!

Back to the dealer who could hear the noise but diagnosed it as a transmission problem. $4k later, new (Ford-rebuilt) transmission and the whine/vibration is still there.

All I got out of the dealer's service manager was "I have never heard of anyone using compression to slow the vehicle."

The sound/vibration is frequency dependent on vehicle speed, but is always there when you load the drive train with engine compression.

What could they have done while replacing the pinion shaft seal to create a problem? What in the rear end would whine/vibrate under deceleration loading?

All ideas welcome and appreciated!

techrep

iTrader: (1)

When the pinion was leaking did you ever add gear oil to the diff ? Has the Diff ever been serviced ?

BadFish523

Do you have a LS rear end? My wife's Explorer has the dreaded LS clutch problem and on top of the rumble around slow corners it also has a slight whine/vibration when simply letting off the gas at say 65mph and letting the vehicle slow itself down. As Tech said. Service? What oil? Friction modifier?

PerryB

Most likely the forward pinion bearing. Its the first to go when the oil gets a little low, and whining on deceleration fits the bill for a pinion bearing failure. Your service writer should work at McDonald's.

BillLee

The leak was never a LEAK, more like one or two drops on the carport floor over a span of 6 months and an accumulation of oil grunge on the diff itself. I trust that the servicing by the Ford dealer maintained proper lubrication, I did not crawl under and check myself. Other than regular oil/filter changes, only for the recent fix of the leaking seal has the diff been serviced.

In retrospect, that trust may have been misplaced.

BillLee

Would replacing the pinion seal have triggered a bearing failure? Is there anything involved in fixing the seal that would affect the bearing itself?

I am looking for a plausible explanation of why the problem I am having seems to have been initiated by the seal replacement.

BillLee

Not sure how to answer: how do I determine if the LS rear end is involved?

As for lubrication: whatever the Ford service department might have used. According to the repair ticket:

BadFish523

http://www.etis.ford.com/vehicleRegSelector.do
Put your VIN in here and read through all the options. It will either say: Limited Slip Axle or LESS Limited Slip Axle


Usually if the LS is the problem you will also notice a rumble vibration when turning sharp and slow. It is a possibility but there would usually be other signs along with the whine while decel.

SCORGE

Your axle code should be on the door jamb.

BillLee

Thanks, StephenG. That's an interesting site.

For my F150, it says "Less Rear Axle Limited Slip Diff", so that rules out one thing!