John Surgener

I don't think this issue is only for 1999 thru 2007 Silverado's but all Silverado's. I don't think anyone has ever heard of this but here's what happened. I had an oil leak, from the rear main seal I thought, and wanted to get it fixed so I took it to a local garage (that I know does very good work) and had it repaired. Along with this, I also had them put in a new fuel sending unit and fuel pump. So they pulled the gas tank and changed the unit and pump and they took off both drive shafts (4wd), pulled back the transfer case and transmission and replaced the whole rear main seal unit w/the aluminum bracket.

After that, when I take off, turn a corner, or put the truck in a bind/twist, I hear and feel a popping cracking noise like something is pushing against something, then moves causing a loud popping noise. I took it back to the shop but they said they could not find anything but they did hear the popping noise.

I searched the internet but could not find anyone with this kind of issue. I thought it might have been the gas tank rubbing against the bed moving some but the popping is coming from the front and rear. I also thought about what they did that could have caused this problem. I read somewhere that the drive shaft slip yoke might be dry, it does move back and forth when taking off, stoping, or turning. I'm going to grease the drive shaft slip yoke soon, not sure if it has a grease fitting or not, but this is a very loud popping and cracking noise. You can even put your foot on the brake and give it some gas and hear it pop.

Any suggestions would be greatly appreciated. This truck is in excellent condition, I keep it in a garage, fix what needs to be fixed, and it looks like it is only 10 years old instead of 22 years old.

Thanks for any help, John

Gumby22

When turning - does the truck have to be moving, or can you cause the noise by sitting in park, engine idling, and turn the wheel back and forth?

Did the shop replace the front or rear driveshaft u-joints while it was apart?

John Surgener

Hi Gumby, the truck has to be moving. Turning the wheels back and forth does nothing. Its the twisting of the body like when you take off (slow mostly), turning shifts the body one way or the other, or stopping. That's why I thought of the drive shaft yokes, The transmission, transfer case or drive shafts have never been off the truck before. I did check the u-joints and there OK, Its a kind of rubbing noise that causes the popping. I have had u-joints bad before, they are more of a clanging noise. This is a low tone, rubbing, popping kind of noise like something is breaking loose. Have not had time to grease the drive shaft yet.
Thanks, JD

Gumby22

A u-joint that has play in it will typically cause a clunking noise - but a u-joint that’s dry or has lost enough grease that it can’t adequately lubricate the needle bearings could cause noise like you describe. I’ve seen several u-joints that have somehow only dried up on one cap despite not having any play and externally looked like nothing was wrong.

I can’t be 100% certain but I don’t think the factory u-joints had grease zerks - it was around this era they changed to a greaseless design. The slip yoke on the front driveshaft should have a zerk.

If you only checked the u-joints for play while the driveshafts are installed, you’d have a better idea of their condition by removing them and working the caps back and forth by hand to feel for smooth motion. You’ll be able to tell immediately if one of them dried out.

As a way to eliminate the driveshafts for sure, you could try removing them one at a time and see if the noise goes away. It won’t hurt anything to drive a short distance at slower speeds with the rear driveshaft removed - just cap off the TC output shaft seal to keep from losing any fluid.

The only other thing I can think of to check is the fluid level in the transfer case. Maybe your shop drained the fluid and didn’t fill it up. Even good techs can still make mistakes.

John Surgener

Thanks Gumby22, I think I will remove both drive shafts, grease the slip yokes good and go ahead and replace the u-joints. They are 22 years old so it won't hurt. As for the transfer case, it started leaking after all this work was done. It may be they drained the fluid and didn't put the plug back on good.
Well, I'm getting to old and out of shape to do much work on my truck anymore so I might take it back to the shop that worked on it and have them do it.
thanks again,
JD

kevinkpk

One thing you should look at is the mounts.

PNW NBS Z71

I first thought of the obvious: the driveshaft slip at the dry splines and the u-joints. Then I thought about the transfer case for fluid level and then as @kevinkpk said, the motor mounts and the transmission/transfer case mount. If you have to be moving and turning, I can also suggest front axle shafts inspection and hub inspections.