Bioboi

Just wanna follow up on this. The transmission went out at 69,000 miles two years later. The dealer said the pump failed and essentially the trans overheated (instantly) and self-destructed. Since we had 3 documented cases of the engine mounts being replaced, and 1 final case of us complaining about it before warranty went out, GM reluctantly paid for a REBUILD of the transmission. Sitting at 83,000 miles now, it drives better. They gave us a 1 year 100k mile warranty on the rebuild. I also bought one of those plug in range things to shut down the useless AFM that ruins lifters and the cam. MPG went up by 2. Hope this helps. If you're having similar symptoms, USE THIS THREAD. ARGUE WITH GM UNTIL THEY GIVE IN. DON'T GET GYPED BY BAD PRODUCTS.

Hello, I have a problem. Last week my dad bought a brand new 2021 Trailboss with the 5.3 and the 10 speed transmission. It had 28 miles on it. The truck now has less than 100 miles on it and besides driving it home from the dealership, he's driven it once (today). He came home and told me to come outside and listen, and the transmission is making a definite clunking sound at idle. It happens maybe every 2 seconds consistently, and goes away when the engine's idled up. I know its the transmission because not only can I feel it when I put my hand on the bellhousing, but I can hear it through the pan and the bellhousing with a screwdriver on my ear. The sound isn't coming from the oil pan on the engine either. Unless this is a documented "quirk" with this transmission that isn't an issue, he will be taking the truck back to the dealer and not driving home with it. We are VERY skeptical of this problem because last summer the 6 speed in our 2017 Yukon blew up at 69,000 miles (conveniently just out of warranty). Thanks for any constructive input you can give to this

Hey guys. Bear with me here this is a long one. Ive got some questions about our 2017 Yukon 5.3. We got it new last August and have 27,000 miles on it. Let me first say that we own a ‘95 C1500 5.7 from brand new and an ‘01 Yukon 5.3 from new. So we own 3 different generations of effectively the same vehicle (or at least the same in terms of drivetrain). (Yes the 5.7 TBI is not a 5.3 Vortec...or EcoTec...you get what I’m saying) Alright now for why I’m here. So at about 20k miles we noticed a vibration at idle and took it in under warranty. They said it was the motor mounts. Said they looked like they’d been through hell and back. That fixed the vibration for a little while. It started again and this time they said it was the transmission mount. That fixed it again for a little while but it’s back again and we aren’t gonna just keep replacing mounts till the warranty expires. So my first question is, why is this thing eating mounts? Also, this truck just doesn’t idle as well as the ‘95 (300k miles) or the ‘01 (400k). Both of them just purr like a finely tuned Bentley. Maybe the mounts affect that but geez for the year 2017 it just sounds rough. I mean, you hear a lot of valvetrain noise and it doesn’t sound as smooth. 2nd question, is that normal? This is the only truck from this generation I’ve been around so I can’t compare it with others. Only to the previous gens. Next, the startup sounds sluggish. Like the battery is discharged. This could be simply a junk battery but if 10 people say theirs do it to, or say it does it even after a brand new battery, I can determine that this is normal. So how do your trucks startup? Fast or slow? Cylinder deactivation. Now I’ve heard this is a sketchy, horrible system, and ours lives up to that. It will switch between V8 and V4 constantly. I’ve heard that if the wind blows the right way it’ll kick up into V8. And yeah ours does that. Any little hill or touch on the throttle it’ll kick up. I just figure they’d program it to be a little more assertive in V4 and let you actually use it. Also, the MPG really doesn’t improve with V4. (It does at like 30mph but that doesn’t count). I notice about 22-24 in V8 at 65, and 20-22 in V4. Also, the engine sounds like crap in V4. You can totally hear the valves and all around more noise from the engine. I just figure in a “luxury” vehicle this should be nonexistent. But again I have next to no experience with this system. 2nd to last question, is V4/V8 supposed to be like what I described? It just seems like a buggy and far from perfect system. Ok last bug - Transmission. This is somewhat related to the cylinder deactivation. This truck has the 6spd and the 3.23 diff. Every time it switches from V4 into V8, the RPMs jump. They don’t jump enough to be going into 5th, so it looks like it is unlocking the torque converter. Then it settles back down in lockup. This is something I would think the engineers would avoid, as an unlocked torque converter at highway speeds in top gears would generate loads of heat and wear. Hence the reason for a lockup. Maybe I’m wrong? Seems unnecessary to jump around so much. My ‘95 will stay in 4th-locked unless you near floor it then it just goes to 3rd. So last question is, should the transmission be so jumpy with the TC? Shouldn’t it lockup in 5th/6th and stay there unless you mash the pedal? Sorry for the small book. I’ve probably broken some rule on this forum for character limit ? Any information or input you guys give will be greatly appreciated. We loved our ‘01 and still love it after 400,000 miles, and we wanna love and enjoy this one too. Thanks