Hello to all:

I have a '97 F-150 XLT SuperCab with the 4.6L motor, automatic transmission and 4x4 Off Road Package with the electronic shift transfer case and limited slip differential. The truck currently has about 106, 000 miles. The rear pinion gears were repaired (?) under the extended warranty at 90,000 miles for a whining noise problem.

I typically put the truck into four-wheel drive three to four times a month while working in the back woods at home on the weekends, but drive only at low speeds.

Recently, we had a significant snowstorm and I used the four-wheel drive extensively and at all speeds. During this time, one drivetrain noise became increasingly evident and a new noise developed. Both noises occur in both four-wheel drive and two-wheel drive modes.

The first noise is a clunk, or clunks, apparently coming from the rear of the vehicle, under acceleration from a stop. The clunk(s) occur when first tipping into the throttle and feel like the driveshaft is turning, but the wheels take a half-second to respond. Under moderate to high acceleration, it sounds/feels like first one wheel clunks and then the second wheel clunks. I had felt/heard these symptoms in the past, but to a much lesser degree than currently.

The second noise seems to be coming from the front axle area and is a constant groaning or moaning type sound that does not appear to be speed dependent. This noise is new, not noticed until the recent use of the four-wheel drive during the snowstorms. I bought the truck new and have never checked the fluid condition or fluid level in the front axle or transfer case. :o

Any thoughts or relevant input into these drivetrain noises will be appreciated. Thanks for your time.

Wilk

 

Check your front fluid levels. My guess is that your transfer case is not the source of your problems, but check that fluid as well. The rear sounds like you might have either a bad u-joint on your driveshaft or the clutchs in the LS are going bad and need to be rebuilt. The front groan may be attributed to a lack of oil and the front diff is eating itself alive. These are just some ideas as its kinda hard to correctly diagnose the problem without seeing it 1st hand.

 

powerstroke 73:

Thanks for your response. As soon as the weather around here clears I will check the fluid levels.

Wilk

 

For what it's worth:

Today I checked the drivetrain components and fluid levels from the transfer case rearward. The findings of these activities follow.

First I backed the truck up so that the rear wheels were on a pair of auto ramps, I then jacked up the front of the truck and installed jackstands under the lower control arms, making sure the truck was level. I then commenced to crawling around under the truck. Gee, I hope a get a new mechanic's creeper for Christmas!

The transfer case fluid level was right where it should be, a slight trickle out of the fill hole when I removed the plug. The fluid appeared to be clear and uncontaminated.

Next I checked the front differential. The differential fluid was found to be slightly below the fill hole. Unfortunately, the fluid had a milky appearance. Apparently water had somehow gotten into the assembly.

I then checked the play in the rear differential. With the transmission in neutral I was able, by hand, to rotate the driveshaft approximately 15 degrees. An unacceptable amount of play, I would assume.

Finally, I checked the rear differential fluid level. The oil level was good, just below the rim of the fill hole. The fluid was extremely black, and the magnetic end of the fill hole plug was loaded with metallic filings.

On my soapbox. (Thank you Tasca Ford Service Department. Once again you have reaffirmed my conviction that Tasca Ford's Service Department is typically inept, and that Tasca Ford cares little about their Service customers, except for the profit margin. Tasca Ford's "fix" of the rear differential at 90,000 miles, while still under the Extended Warranty, lasted 16,000 miles. Now the repair for the rear differential will come out of my pocket.) Off my soapbox.

I subsequently drained the milky fluid from the front differential, and refilled the front case with a little less than two quarts of Mobil Synthetic 75W-90 gear oil.

I took the truck off the jackstands and ramps, and went for a test ride. I engaged four-wheel high, and drove several miles on mainly straight roads. By the end of the test ride, the noise from the front was virtually gone. I hope there are no long-term consequences from getting water into the front differential.

My next actions will be to arrange for the rear differential to be inspected and repaired, as necessary.

Thanks for letting me vent my frustrations.

Paul Wilkinson