Are my U-joints going out?

[renchhednot]

Hi all- My '94 F-250 started making a grinding noise coming from underneath yesterday. It grinds for maybe 10 seconds and then stops. Is this u-joints and if it is I heard it is a fairly easy fix. Can anyone help?

[2.2 Straight six]

ok, let's get the basics first.

what engine?
manual or auto?
milage?

you need to pinpoint the sound and where it's coming from. it could be anything for a bearing going out to gearbox issues.

u-joints on the driveshaft are pretty easy to fix. if you mean u-joints on the front axle (if it's a 4x4) then there's more work involved.

[mikecee48]

The noise could be the u-joints or something else, like the transmission. How many miles do the joints have on them? Depending on what the truck has been used for, i.e. much towing vs. light duty, they could wear out in 90,000 miles or make it to 125,000 miles or so.

The usual test is to apply the emergency break, get under the truck and try and twist the drive shaft on each side of each u-joint to see how play is in each joint. One hand on one side of the joint, the other hand on the other side type twist. If there is much play at all, at the joint, it's time to replace it. If you're unsure about your test or reluctant to try this, have you favorite shop check the joints for you. I haven't priced them in many years, but I guess they'd be about $65-75 each, parts and labor.

Don't delay much on this as a badly worn out joint could break apart while driving. If you've ever seen a car on the side of the road with the drive shaft hanging down, that's what happened. It's also dangerous if the front u-joint comes apart while on the road as the vehicle may have a tendency to pole-vault over the drive shaft when the front of the shaft hits the ground while the rear of it is still connected to the differential.

Usually, a worn u-joint makes a whining sound while at highway speed that varies in intensity as you travel over bumps in the road. This is because the angle on the u-joint changes as the rear wheels move up and down. Due to the stiff suspension on a truck, this worn-out signal is less apt to heard than with an ordinary rear wheel drive car. A truck would more likely give this noise if it had a heavy load in the bed.

[renchhednot]

Ok the truck is a 351 Windsor with maybe 170,000 miles. I bought the truck at maybe 155,000 miles. I just had the steering gear box replaced with new lines by a friend who is a diesel mechanic for a large construction company. The noise sounds like the wheels are locking up. I replaced the front wheel bearings maybe 4,000 miles ago or less. I know the rear isnt sticking. It sounds like its coming from the front wheels. It is an automatic with real wheel drive. The tranny was just flushed also.

[mikecee48]

If this noise is happening with the brakes applied, the truck could simply have worn out brake pads or rear shoes. A grinding noise may be that the front pads have completely worn down to the pad metal. I've seen this happen without the proverbial squeal of worn down pads. If you can see the outside of the brake rotor, through the front wheels, and it looks deeply scored, chances are a full brake inspection is needed to confirm this possibility.