BarbaEnzo

Recently took my Ford F-150 2002 XLT Crew Cab 4WD, into the shop to get a Smog and Oil Change. Oil change came with a lube, fluids check and tire rotation. Before arriving to shop my truck had a creaking noise in the rear when I would initially drive from a stop. It had been going on for a few weeks but was not always making the noise and was very minimal sounding.

When I picked my car up the shop said that my differential fluid was low and they noticed metal shavings around the fill plug. they filled up my fluid. They also noticed that the pinion seals were seeping.

When I drove it home, initially it was running very smooth. About 25 miles in, I rounded a corner and started to hear a loud grinding sound. The next morning as I was driving it back to the shop the grinding noise got worse and then from a stop the truck started to make a loud clanking and jerking motion from the rear, as if gears were skipping.

The shop re-inspected the truck and determined they would need to replace the rear differential and U Bolts at an estimated $2500.

By the way, they also said they have never seen anything like this before and that it must have been a coincidence it happened at the same time. After all the truck drove fine before the service call, aside from a slight creek in the rear end.

Can anyone provide any insight on this diagnostic and cause of the problem? Can it really just happen coincidentally or maybe they aggravated the creaking issue into this more serious problem?

Is this task something that only a shop can perform or could I possibly do it myself?

I have already put a lot of $$ in this truck in the recent year for an engine rebuild after a spark plug coil cause an issue where a part of the engine had to be machined (heads I think). It only has 100,000 miles on it.

Is it worth more effort to fix this new problem?

Any help is greatly appreciated.

woodlit

Not to be mean, but if you don't know what was machined on your engine, I'd leave the diff replace for the shop.
Pure guess here... Your diff probably lost a tooth chunk somewhere along the line, and it got stuck to your magnet, like it should have. When they removed the plug, the piece might have fallen back down, maybe too big for the fill hole. Then when driving home, the broken piece found a home where it shouldn't have. Jammed the the pinion, a spyder, etc.
things like that happen to radiators after flushes allll the time.

Marc D

Ford rear differentials require special additives (modifiers) to be added to the gear oil to help lubricate the clutches inside the housing. Over time they (modifiers) can break down causing dragging and excessive noise. Fine shavings on the plug are not always an indication of a damaged ring and pinion gear, but can be an indication of wear. I would suggest before you spend that kind of money, I'd remove the cover of the differential, draining the gear oil into a pan and do a visual inspection of the gear. If you put the back of the truck on jack stands, blocking the tires in the front, and the trans in neutral,you can have a friend rotate the rear wheels while you inspect the ring gear. If you find metal chunks in the oil or teeth missing, the gears are bad. You'll need an axle assembly since metal can work its way out to the wheel bearings. This is a difficult repair if you have never done it before and should be left to a shop.
If you only find very fine metal shavings, you can clean out the housing, replace the cover with RTV sealer and add new gear oil and modifier and see if the problem goes away.

BarbaEnzo

Thank you for the quick replies. And [MENTION=30583]woodi[/MENTION]t, no offense taken. I have done a few car repairs successfully myself, but it has been years. I didn't plan on doing this myself but have an acquaintance that is a retired Ford certified mechanic, that has his own shop and was considering having him take a look at it. I didn't want to waste his time if it was deemed to be something obvious.

It does sound more likely to be a big gear chunk in there based on what I have heard and felt when I was driving it. I am still hopeful that it may be what Marc suggests, so maybe once I get it towed home I will take a look.

Thanks again for the help with this!