GsBowtie

Short answer, no. You're local tech should have been able to check vaccum. However, these new trucks are very complex so it takes some understanding of how everything is integrated. It's not getting any easier by any means

I'm not in the running for this. 2015 z71 cc, bought in may of 15. 9800 mi or so. No major issues to date.

My brother's 14 had this around 40k and needed a new radiator. If under warranty take it to the dealer. It should not do that

I had the tsb done on my 15 a month or two ago and it's been rock solid since. No movement at all. This is the tsb with the shim kit and the extra clamps (black) next to the white factory ones. Seems to working so far. I didn't have a bunch of left-right movement before, but it was there and i didnt want it to get worse. So far so good.

Flapper valve in the exhaust possibly? I don't notice any noise like that in my 15, but maybe I'm just not noticing it

These direct injection engines have noise at idle. It's probably normal

I thought i posted this prior, but, i checked my 15' Silverado, 10/14 build date this morning. It appears that my truck already has that bracket installed on it from the factory. I can see the muffler from the top side and the sensor and it connects the two lines.

I just looked at my truck. 10/14 build, 2015 MY. My truck has the muffler, but also appears to have the bracket already installed. It's mounted sideways between the two ac lines and is near that muffler. Hopefully mine is good to go

Update; no real change (with vibration, i had none before ) i can tell on my truck with u bolts torqued to 79 ftlb and my clamps on the aft portion of the spring, 3" from the end (top 2 springs only) I do believe one change i do notice, unless it's just my mind wanting me to, is the forward to reverse clunk is gone and the movement i felt sometimes on the transition from my shop floor to driveway seems better. This could also just be in my head, but the rear suspension seems more solid now as well. All in all a good change for me, so thanks guys!

I have no vibration issues, but sometimes feel a clunk when shifting from forward to reverse and sometimes when I put my truck in gear before the rpm drops to normal idle. So I decided to check my u bolt torque. Mine were in the neighborhood of 50 ftlb. Not enough in my opinion, especially considering I tow a 6000 lb travel trailer. I also didn't like how the rear portion of the leaf spring did not have any clamp holding the two leafs together from the axle all the way to the rear, so I put a clamp on the rear about 3" from the end of the second leaf. So now at least the front portion of the leaf has the factory clamp, and I have the advance auto one on the rear. I painted the clamp black before I installed it to prevent rust. I'm interested to see if this will get rid of my clunking. If it has an adverse effect I'll let you know

The sound I'm referring to is NOT a fuel pump. That sound is very ovbious after the guy first turns the key on. The rattle / rrrrp/ rasp or whatever you want to call it happens just after the engine fires. My truck does that pretty much year round on the first start of the day or when I'm leaving work at night. I hope no long term engine damage is being done for those first few seconds there is no oil pressure. It sure sounds like VTC rattle to me, but I've never had one of these new engines apart yet. Sounds like metal on metal to me, but hopefully I'm wrong.

I guess I won't worry about it then. Good to know though

Thanks for this info. I do think the issue is from the oil pump now. The description in bold reminds me of what mine does on cold start "rrrp or rasp " that's the sound a few seconds after the engine fires on that video and my truck makes on cold starts

I don't think it's the di pump, i can hear that prime when i turn the key on before I crank. It's some sort of rattle

Lol i agree. Yes if I remote start with the house door open i can easily hear it right after the engine fires, just like in the you tube video. I'd just like to know what it is. I don't like it, that's for sure

Hey Y'all, I posted this tread in the engine forum, but I want to post here because after doing more research, It may not be an engine sound after all? http://www.gm-trucks.com/forums/topic/182875-slight-rattle-at-cold-start/ When I was doing some research, I found this you tube video which has the exact same noise my truck and my brothers 14 makes: Does anyone have any ideal what this noise is? If it's normal, that's fine. Sounds like VTC rattle like I had on my 14 CRV's that I got rid of, but I've read it's the flapper valve in the exhaust, or something in the transmission re-setting during the first cold start? Whatever the sound is, I'd like to know what it is exactly so I can feel good about the truck and move forward. I can say for sure when it's extremely cold outside, the noise is louder/longer, but it has done this pretty much from the first month I have owned the truck. I want to say it's a light rattle, or whirring noise, but much like the VTC in the CRV's it sounds metal on metal to me. Just curious about this and if anyone ever got to the bottom of what this cold start noise is. Much like the VTC rattle on the CRV's the noise (again, see you tube video link at about the 30 second mark, just after the engine fires, it's slight, but is noticeable) my truck only makes this sound on the first cold start of the day or after sitting several hours. Any help or insight anyone could offer would be appreciated. Thanks. G

I did some Internet searching and found this thread; http://www.gm-trucks.com/forums/topic/176420-weird-sound-at-startup-2015-sierra-denali/ This is exactly the noise I'm referring to. Check out the video at the 30 second or so mark right when the engine starts. Is that noise really just the exhaust flapper?

That's interesting. Did you start it with the door open? That's the only way you can hear it. It only lasts a second or two, very brief. It sounds like vtc rattle to me, but i was hoping someone more knowledgeable than i on these new engines would know. My brothers 14 also makes the same sound and its worse when it's real cold outside.

Hey guys, I've noticed our trucks (5.3 anyway ) make a slight rattle at cold start. What is that noise? My brothers 14 does the same thing. You have to start it with the door open to hear it. I had 2 2014 honda crvs that had the infamous cold start vtc rattle. Is that what we have going on to? (Camshaft vtc actuator rattle? ) i got rid of the Vs due to that bc it was bad. Just wondering what you all think that is. Thanks G

Just goes to show you how much markup dealers normally charge!

Hi Tbarn, Thanks for your post. Can you tell us what is involved in the dealer (GM) repair of these seats? Does the seat have to come out of the truck and what parts are installed/swapped that anchor the lower seat pad/frame so it does not shift around? have you seen this on 14's and 15's? Thanks, G

Excellent info. Thanks for confirming that information. I see no reason not to put the clamps on now. If it does not affect the functionality of the seat. One interesting thing I noticed is my seat only seems to move after the trucks sat outside in the sun all day at work. (And parts have expanded)?? I notice the movement on the way home. It's very slight but I notice it. Feels like the seat bottom is shifting side to side slightly when in turns when a load is against it. It's odd to say the least

I believe my 2015 is starting to have this issue. I've noticed some very slight movement in my seat bottom at times when I'm taking left and right turns or curves in the road. If not for this thread I'd probably not even notice it. I have about 2200 miles on the truck now, so this is pretty irritating to say the least!) At any rate if I use the hose clamp fix ,(it bothers me a lot to have to do this on a brand new expensive truck!!!) But I was thinking about using some 3\4" heater hose for my rubber. Any thoughts on that? It is pretty sturdy stuff. I took a quick look at my seat bottom this morning and I can see the infamous white brackets. Who would use this for a seat in the first place? What a weak, dumb design. When I touched the round steel bar it had some sort of lube on it, so I'd assume that has to be cleaned off first? Also can the seat be adjusted fore and aft, up and down after the clamps are on? Do they side with the plastic clamps somehow? I'm just trying to understand how the seat itself operates before i install the clamps.. I figure the dealer is a waste of time so why bother and might as well put the clamps on now if there are no adverse effects before it gets bad right? Thoughts? Thanks G

On a recent camping trip I averaged around 12mpg towing my approx 6k TT. Not tobad considering the truck only had about 1500 miles on it it at that point. My old 2000 ford expedition towing the same roof was around 8mpg or so.

I'm 5'4" and find the pedal location and spacing no problem. But I've driven a lot of trucks, some medium and heavy truck also. I don't find the spacing any different than other trucks I've owned. Agree with the post about the brake pedal feel on the truck. In the past i have always felt GM products were "under braked" not so with my 15 silverado. They feel strong and were strong when pulling a heavy load on vacation. Yes i have trailer brakes but the truck cab rear and bed were loaded with gear. Despite that i never had any brake fade on the downgrades. I always felt like there was plenty of pedal left. Just my .02. But GM got the brakes right on these trucks