Introduction and request a diagnosis of a very loud cold start sound

[Fless]

So really low on fluid. LOL

Good, one thing eliminated. It wouldn't hurt to pull the serp belt and start it cold, see if the noise remains.

 

[89Suburban]

electric steering on those, no pump

 

[Doubeleive]

So I bought a stethoscope and checked the pulleys on the AC, the accessory bodies of the alternator, and the air pump. Nothing that mimics the outside rapid clang. The fans are electric and dont operate on a cold start. The A/C turned off. The only thing I’m thinking it might be is a loosened bolt to a heat shield. It sounds inside the engine bay like metal clang/vibration- tin like. Perhaps when the engine warms up and the sound disappears, maybe the heat expansion of the bolt tightens the loose area. I don’t have a lift, so sadly I will take this to a mechanic and have them address. I will post what they find/fix. TY all for sharing your knowledge and time. Best, Stephen

def not a exhaust leak, take the serpentine belt off next time all it takes is a 15mm socket on the belt tensioner, just use a long ratchet and apply pressure, the belt will come right off and then go right back on after you see if the sounds is gone, if it is not the fans then I would suspect the smog pump I have heard they make noise when they go bad I just have never heard the sound yet so can't reference it for sure.

 

[RB_Trucker]

So really low on fluid. LOL

Good, one thing eliminated. It wouldn't hurt to pull the serp belt and start it cold, see if the noise remains.

As soon as I heard that video I instantly thought power steering pump.... it can be electric or belt driven and it’ll make that whining noise with low fluid until the fluid warms up enough to the Hot/low or the Cold/full mark on the reservoir.... top it off and should go away, if not then a new pump is needed.

Very slow leaking hose somewhere or the steering Rack is leaking.... @74k and if in a snow state that uses Salt that could be a corrosion issue...

 

[stephen sibilia]

Ok- Shocker... I took the Yukon to a mechanic I know. He called me this am, after the cold start, and put it on the lift. " Have you had your starter replaced or any transmission work done"-me: No, although i did take it in to the dealership 2 years ago for a transmission harness recall(something like that.) Why I ask?? - "Well I removed the under pan and found bolts sitting in the pan, these bolts were used for the starter(not all of them came out) and a shield. The shield was lose, no longer connected and caused the rattle. The was a bolt missing as well. The GMC dealership likely didnt torque them to spec, and overtime they came loose. No damage to flywheel or starter". Mechanic re-torqued and added a missing bolt. Charged me 2 hours of labor- $220.00- Problem solved. I'd rather not post the dealership name(I moved out of GA June 2019 and now live in NJ.) GMC dealership is in Roswell, GA. Only 1 there. In case anyone gets work done there. INSANE. That recall was done 20k miles ago, If my memory serves me. All TY for all of your suggestions and help.

 

[RB_Trucker]

Ok- Shocker... I took the Yukon to a mechanic I know. He called me this am, after the cold start, and put it on the lift. " Have you had your starter replaced or any transmission work done"-me: No, although i did take it in to the dealership 2 years ago for a transmission harness recall(something like that.) Why I ask?? - "Well I removed the under pan and found bolts sitting in the pan, these bolts were used for the starter(not all of them came out) and a shield. The shield was lose, no longer connected and caused the rattle. The was a bolt missing as well. The GMC dealership likely didnt torque them to spec, and overtime they came loose. No damage to flywheel or starter". Mechanic re-torqued and added a missing bolt. Charged me 2 hours of labor- $220.00- Problem solved. I'd rather not post the dealership name(I moved out of GA June 2019 and now live in NJ.) GMC dealership is in Roswell, GA. Only 1 there. In case anyone gets work done there. INSANE. That recall was done 20k miles ago, If my memory serves me. All TY for all of your suggestions and help.

Wow bro that’s insane, well I’m glad it wasn’t anything massive or being destroyed beyond repair....