2004 Chevy Silverado loud noise in back end when driving highway (clunk maybe not sure)

[Railin]

It all started pulling out of O’Reilly’s one day. At a slow speed (5mph or so) I got a jerk in the back end, at least that’s where it felt like it was coming from. Eventually I got going and I was on the highway for 30-40 minutes, everything seemed normal and all of a sudden at 55 mph it would do somewhat the same thing, almost felt like the drive shaft was stopping and going, very loud and then there would be no power, hit the gas and nothing. So I let it go down to like 10mph (automatic) put it in neutral and back and drive and then she was back on track in gear like normal but then it did it again after while, made it to where I was going thankfully but it was the most nervous/sketchy situation ever. Has anyone experienced this? I’m thinking the diff or the transmission, just trying to pin point where I should start from. I’m not a master mechanic but I can get by with watching videos on different problems if they arise. Thanks. 

[asilverblazer]

18 hours ago, Railin said:

It all started pulling out of O’Reilly’s one day. At a slow speed (5mph or so) I got a jerk in the back end, at least that’s where it felt like it was coming from. Eventually I got going 

You were going slow... applying throttle? coasting? braking? 

 

Jerk? like being rear-ended, suddenly stopping, suddenly accelerating?

 

What was the engine doing? Free revving, idling?

 

Eventually I got going, indicates no forward movement... explain.

 

18 hours ago, Railin said:

everything seemed normal and all of a sudden at 55 mph it would do somewhat the same thing, almost felt like the drive shaft was stopping and going, very loud and then there would be no power, hit the gas and nothing. So I let it go down to like 10mph (automatic) put it in neutral and back and drive and then she was back on track in gear like normal but then it did it again after while

How was it different other than the speed? The driveshaft will never stop going... if it does it will be very obvious and very bad. What is very loud? One bang, multiple bangs, grinding? When this is happening what else is going on, is the engine revving, does putting the gear selector in neutral or drive change anything?

 

18 hours ago, Railin said:

I’m thinking the diff or the transmission, just trying to pin point where I should start from. I’m not a master mechanic but I can get by with watching videos on different problems if they arise. Thanks. 

Mileage?

Drivetrain?

Maintenance?

Check engine light?

Visible damage underneath?

[richard wysong]

4WD? could be the transfer case

[Railin]

I was leaving the parking space, in drive so just coasting like less than 5 mph. The front of truck seemed fine as far as the engine, it was just the back like under the bed it felt like a multiple jerk or maybe pop. Like your sitting in drivers seat and it’s a bump bump bump, I said eventually got going meaning I got past that phase, going past 10-15mph and it seemed normal but as I stopped at a couple traffic lights it only did it when I lett off brake and giving it a little gas  0-5mph or so phase. Once I was on highway it was fine going at a higher speed but after like I said 40 min or so going 55mph it felt similar almost like a loud jerk/rattle from the back and the truck was still running seemed fine as far as engine but when you hit the gas there was no power, it wouldn’t go, even tried at that speed to put it in neutral and back in drive and nothing still no power, I let it glide down in speed to 10mph did the same neutral and then drive and it was back in gear and started going again. Truck has 250k, 4WD, check engine light was on at the time but was only pulling a couple minor codes that I can remember and there was no visible damage underneath everything looked normal at the time under there.  

[dna9656]

Because it was different when you operated the tranny shifter I'm thinking your tranny is where your problem is. True the G90? Rear axle has issues from time to time but Spicer has been building rear axles for a long time and they are not accursed with computer controlled sensors (except anti skid and that's on the axles proper) and other such mandated crap. Do you use the transfer case often/a lot? If not it's prolly ok. I suspect the tranny, the 4L60 E can have a lot of problems, problems that are fixed with a rebuild, I got mine upgraded to a 4L 70E, more clutches other stuff. It's the tranny used in the Caddies and the SS cars.

[asilverblazer]

13 hours ago, Railin said:

so just coasting... the back like under the bed it felt like a multiple jerk or maybe pop... a bump bump bump. It did it when I let off brake and giving it a little gas  0-5mph... Once I was on highway it was fine going at a higher speed but after 40 min, going 55mph, it felt similar like a loud jerk/rattle from the back, when you hit the gas there was no power, it wouldn’t go, even tried at that speed to put it in neutral and back in drive and nothing still no power.

It sounds like the noise goes from bump, bump, bump at low speeds to a rattling noise at higher speeds. Happening at low speeds in first gear and at high speeds in overdrive sounds like it isn't the transmission.

 

When you "hit the gas there was no power" were the noises occurring?

 

I'd pull the rear diff cover and inspect.

[Railin]

I want to say when the loud rattle happened at 55mph it was close to 5 seconds mayb (the nosie)  and then it stopped and I went to hit the gas and nothing as far as power, just let it glide down to a slow speed and then neutral back in drive and there is where it started rolling again. Never experienced this sort of thing happen and I’ve had quite a few things happen in the past but nothing that sounded this bad. btw I don’t use the 4wd often either, it’s been quite some time. I’m going to remove the bolts and cover from the differential here soon when I can get a break from work and see what I find and go from there, I may take some pics as well for reference bc not sure If i’d be able to tell but then again if it doesn’t look right you should be able to. Thanks for all the feedback from y’all so far, it gives me a path to take and see what happens. I love my Chevy and I know the engine is still strong, ya know you can feel it over time so may the luck be on my side this time. 

[Railin]

I believe I have found the culprit. Thanks again to everyone for the replies and especially to asilverblazer for the tip on pulling the cover and inspecting, not sure why I didn’t do/think of this sooner. Now going to figure the best way to button this up either by replacing the gear/gears or just getting another rear end. 

[asilverblazer]

Houston, we have a problem. 

 

At least you know whats wrong now.