Off the top of my head I'd say check your u-joints. It sounds like you are describing the classic sound of one with a u-joint that is starting to go bad. Does it clunck (noise wise) louder than normal lately? You may also hear a sound like a "ping" when putting the truck in gear when they go bad.

 

I will check the u/joints today. The noise is virtually unexistant untill I start to go forward and forward only. When I would start up the truck there is also one or two clicks. It's more of a click/cracking sound that a clunk. If I start off in 2nd the noise also seems to be louder than in any other gear. If I coast the noise again is not there till gas is applied.

My truck is a 2wd with a 2 piece driveshaft. If that helps.

 

Sounds more and more like a u-joint problem. Check the carrier bearing as well while you have the shaft out.

 

I did not take the driveshaft off today. My dad got his tonsils removed yesterday so I have to take care of him. He does not let me use the car lift alone at his shop. I was able to get the rear differential on jack stands again and looked around. When turning the shaft in the direction that would go forward their is a squealing noise coming from where the yolk and tranny mate. The center support bearing also seems to be loose in it's holder. The inner bearing race does spin while the outer race stays put but there is alot of play. Is that normal? There is also no play in the u-joints.

 

The center bearing is usually surrounded by a rubber bushing. Some movement is normal (in the bushing part). Sometimes you haver to remove the shaft to actually be able to tell the u-joint it bad. They can feel good and tight when you tug on the driveshaft but when you get them out you can feel if they are dry and the needle bearings are bad/dry. If the yoke will not flop around easily by itself when you turn the shaft in your hand, the u-joint has problems.

 

I now get the noise in neutral and during idle. The noise seems to come from the transmission bell housing area?

 

I'm not sure how they are bolted or welded on a Silverado but years ago I had a Monte Carlo that sounded the same and it turned out to be some loose bolts holding the flywheel.

 

How exactly would those bolts loosen up? Taking off the flex plate bolts on an old 350 was hard enough. Hopefully it isn't that but I will look into it. It is bolted btw I didn't know that fly/flex wheels ever came welded onto the crank.

 

I was thinking an automatic. This was a flywheel ring bolted to the torque converter. I should have noticed you said about taking off in second gear.

 

Possibly the bolts holding the clutch asembly together ? What about the throwout bearing .:?

 

Its is an automatic. When I mean starting in second I mean the second gear. When you select 2nd gear on the shifter the transmission stays on 2nd it does not go to 1st.

How do I access the converter bolts? I had the truck up on the lift today and ruled out that it is nothing related to the drive shaft as the noise is now hear during idle. The truck still runs smoothly but the noise is for sure not anywhere near normal. There are only two plastic plates covering the ends of the belhousing that don't look like they line up to where the converter bolts are.

Could it be engine knock? I run 91-92 octane and synthetic 5w-30

 

I think you have to remove the starter to accedd the torgue converter bolts. Have you run the truck while you were under it (while it was on a lift) to see if you could narrow down where the noise is coming from?

 

I did not run the truck while it was on the lift, I have no idea if it would be safe or not. The noise does seem to be happening around the bell housing area. I am just hoping it isn't engine related.

The lift is a two post lift, is it safe to start up the truck on it? it seems as if the truck will get shaky since the lift points are relatively close.

 

I run them all the time on mine. Just make sure it is not in gear when you let it back down. I've got a Rotary SPOA10 2 post asymetrical lift. I've never had a problem with doing it on mine.

 

Alright I will try that tmrw.

Also just because I remembered, when shifting into drive from reverse, there is a couple of fast paced clicks. The sound is somewhat identical to loosening a extremely torqued down rusted bolt how it makes that click or "ceek" sound. The sound does not happen in reverse oddly but will do it at acceleration, idling, and tapping the accelerator.

 

I know you say you checked the u-joints, but what you describe sounds like typical u-joint problem noises. The only other thing I can think of is maybe a spring bushing in a leaf spring. Have you checked the rear suspension out really good?

 

Did not check the leaf springs. The noise happens when stationary in park, I know the driveshaft spins in neutral when the rear diff is jacked but thats not the case. It kind of sounds like a penny in a dryer, the beat is inconsistent, sometimes it will beat consistent but now it is random clicks here and there at different tempos.

 

Without actually hearing it, I'm still gonna have to go with a u-joint problem, from your description. The driveshaft does not have to actually turn to have the noise. The torque applied to it when putting it in gear is enough to make it make the noise when first putting it in gear. They usually have a rally high pitched "tinny" sounding ping or "ting".

 

The sound is not that high pitched. Can you run the truck without the driveshaft or will fluid spew out the hole the yolk is? Any idea how many splines the 4l60e has? I have a couple yolks laying around I can jam in there if it does

 

That's a good idea, but it will not work. The yoke would fly right out as it would still be spinning and there is nothing to hold it in place. Have you checked the engine and transmission mounts?

 

All mounts are solid. Is it possible for it to run without the yolk? Or will I get a sprinkler of ATF? Someone also suggested a exhaust leak? The noise does come from the general area.

 

You can not run it without the yoke. It may be an exhaust leak. It is possible.

 

I hate finding the source of noises...I haven't thanked you yet ASTE25 or Jordan for really helping me figure this out. I will post again after I do another check.

 

Yes, please keep me updated. It may help me answer someone elses question quickly next time.

 

I would look for a cracked flexplate. I have had one do that before, and it sounds exactly like what you are describing. The one I heard was on my brothers 89 3/4 ton ext cab with a 350. The flexplate was broken in a complete circle just outside the crank bolts. There was one v shaped area between two of the bolts that allowed it to still turn the torque converter. You will have to remove the starter and all of the torque converter bolts to be sure this is the problem. After doing that try to move the flex plate of it is loose it is broken. Good luck