Need a diagnosis from you guys

[Super Diesel]

Hey guys,

I've got 163k miles on my truck (see signature for intel) and I've started having some minor issues over the past 2 months that have gradually gotten worse and worse. Here are the symptoms...

1) Whenever I'm on the road and take my foot off of the gas pedal, and then re-apply force on the gas pedal---I hear a dull "thump" coming from below the truck. Not only do I hear a "thump" but you can also feel a slight vibration too. This only happens when i re-apply gas after letting off of it.

2) I've now noticed that this "thump" also occurs when I'm parked, and then move the transmission into Drive. Once the transmission changes gears, I hear and feel the "thump" again.

and finally...
3) I've been getting some vibrations whenever I'm at 45 mph, very feint but definitely there. The vibrations have also moved to around 50 mph now. And if I'm trying to go over 75 mph, the vibrations get severe.

I was originally thinking that something came loose from the exhaust system, which would explain the "thump" from me getting back on the gas. But now after noticing the "thump" whenever I simply put the truck in Drive, I'm thinking this is a U-Joint dilemma--which would also explain the vibrations at various speeds.

Let me know what you guys think. I'm going over to a friend's house either this week or next to take a closer look. I've used the search function here, but can't seem to find similar symptoms to what I'm having. Thanks guys!

[STROKE_THIS_F-250]

Could be u-joint, carrier bearing etc, check all of them.

[Super Diesel]

Originally Posted by STROKE_THIS_F-250

Could be u-joint, carrier bearing etc, check all of them.

Will do, I'll check them all. Any places you know where to buy replacement parts for a good price?

[cj45lc]

I just bought u-joints from NAPA for mine. They were 20-25$ , the grease fittings point towards the driveshaft.

[Super Diesel]

Originally Posted by cj45lc

I just bought u-joints from NAPA for mine. They were 20-25$ , the grease fittings point towards the driveshaft.

Awesome. Thanks man! I'll get under the truck and give everyone a diagnosis on what I find. Hopefully later this week!

[Super Diesel]

Just wanted everyone to know that I've pretty much found (I believe) the source of my problem. Definitely a U-Joint. For sure. Got under the truck yesterday and found one of the joints to be very loose. Ordering the part and getting it fixed by this weekend. I'll give everyone a report later, hopefully this fixes the problem.

[cj45lc]

Originally Posted by Super Diesel

Just wanted everyone to know that I've pretty much found (I believe) the source of my problem. Definitely a U-Joint. For sure. Got under the truck yesterday and found one of the joints to be very loose. Ordering the part and getting it fixed by this weekend. I'll give everyone a report later, hopefully this fixes the problem.

Might as well put some grease on the slip-joint while your under there, let me guess it's the joint next to diff

[Super Diesel]

Yep, that was it! Replaced both U-joints and everything runs great now!

[cj45lc]

Good deal, glad you got it fixed

[CRANKIN99]

here is a good one, ever hear of the same symptoms, but with good u-joints and carrier bearing?