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

[stephen sibilia]

Hi, my name is Stephen. I have owned my 2015 Yukon XL Denali since new, the Yukon has 74500 miles. In the last 4 days upon a cold start a very loud vibrating sound emits from passenger side front engine compartment. I live in NJ, cold per usual. The sound disappears after 5 minutes. NO codes, NO CEL. I recorded a video with sound. file:///var/mobile/Library/SMS/Attachments/10/00/271AB544-B073-4C7E-9F1F-D5E32D154BE1/IMG_0783.MOV I hope that loaded up. I have been searching for 4 days straight for a video discussion of a similar sound. Anyone have an idea, would love to know before I take it to a mechanic. I can wrench, but no lift, or room in garage. I love the truck, have done all scheduled maintenance, and all recalls. It’s such a LOUD noise, can’t not address. Thank you in advance and look forward to contributing and meeting other owners!

 

[OR VietVet]

First: Welcome to the forum from Oregon.

Look for a broken exhaust manifold stud that when the manifold gets hot the noise goes away. If is loud should be easy to isolate. See if noise is there with the defroster turned off on a cold start. May have an a/c clutch bearing or clutch assembly starting to go bad and those are activated when defrost is on but the bearing is rolling all the time the engine runs. Could be a belt noise, belt tensioner or belt idler. More ideas will follow.

 

[stephen sibilia]

Hi, my name is Stephen. I have owned my 2015 Yukon XL Denali since new, the Yukon has 74500 miles. In the last 4 days upon a cold start a very loud vibrating sound emits from passenger side front engine compartment. I live in NJ, cold per usual. The sound disappears after 5 minutes. NO codes, NO CEL. I recorded a video with sound. file:///var/mobile/Library/SMS/Attachments/10/00/271AB544-B073-4C7E-9F1F-D5E32D154BE1/IMG_0783.MOV I hope that loaded up. I have been searching for 4 days straight for a video discussion of a similar sound. Anyone have an idea, would love to know before I take it to a mechanic. I can wrench, but no lift, or room in garage. I love the truck, have done all scheduled maintenance, and all recalls. It’s such a LOUD noise, can’t not address. Thank you in advance and look forward to contributing and meeting other owners!

First: Welcome to the forum from Oregon.

Look for a broken exhaust manifold stud that when the manifold gets hot the noise goes away. If is loud should be easy to isolate. See if noise is there with the defroster turned off on a cold start. May have an a/c clutch bearing or clutch assembly starting to go bad and those are activated when defrost is on but the bearing is rolling all the time the engine runs. Could be a belt noise, belt tensioner or belt idler. More ideas will follow.

ty for these. For some reason, and I’m def not savvy-I recorded a 8 sec video just for the noise. But I guess iPhone video isn’t making proper extension. I can’t post it in thread. I did turn AC off to check/eliminate- not that. Weird observation, I did notice the oil pressure when driving 2-3 minutes in, sound still evident, the pressure would jump 50+ , not sure if that is relevant. After a good 10 minutes, car is normal.

 

[OR VietVet]

The video has to go thru you tube or some other form. Will not load direct from your phone.

 

[stephen sibilia]

ok I think I figured it out. TY!

 

[wjburken]

ok I think I figured it out. TY!

That doesn’t sound exhaust or engine related. Sounds like a pulley or fan motor. I think A/C was mentioned before.

I’d go get a mechanics stethoscope from Harbor Freight or Auto Zone and carefully poke around and see if you can pin point the location of the noise.

 

[OR VietVet]

That does sound like a noisy a/c compressor internal valve problem or maybe even a partially clogged/blocked a/c orifice that evens out after running for a while. Does the noise get louder/faster if rev the engine? It may well be a belt tensioner or idler that is starting to fail and then after running it goes away. That noise is loud enough that if you get that mechanic's stethoscope, like @wjburken said, you should be able to pin point the source within the 5 minutes you say it takes to stop making the noise. Also, as he said, be very careful where you use that probe when sticking it down close to moving/spinning parts. You can probe right behind a spinning pulley and touch close to where the bearing is at but try very hard not to contact the spinning pulley itself because if you do, the probe could be pulled in and jerk everything off your ears or it will cause such a screech noise on contact that it will amplify in to those ears and sound like a freight train right over the top of you.

 

[Doubeleive]

ok I think I figured it out. TY!

unplug the electric fans and then start it up for a minute and see if the noise is gone, you wont hurt anything to do that, just be sure to plug them back in after you shut if off
if the sound is still present then try the ac belt, that belt is a stretch belt and take's a little tool to get it off or on
if it's not the ac or fans then it could be the smog pump, in which case you would take the serpentine belt off to check that just takes a 15mm socket and ratchet very simple to do.
otherwise it may be something else like the starter solenoid not disengaging all the way and it is touching the flex plate.
not a whole lot things it could be and certainly doesn't sound very serious, if it is the ac pump that it not a cheap fix but that is just the way things go sometimes.

 

[OR VietVet]

unplug the electric fans and then start it up for a minute and see if the noise is gone, you wont hurt anything to do that, just be sure to plug them back in after you shut if off
if the sound is still present then try the ac belt, that belt is a stretch belt and take's a little tool to get it off or on
if it's not the ac or fans then it could be the smog pump, in which case you would take the serpentine belt off to check that just takes a 15mm socket and ratchet very simple to do.
otherwise it may be something else like the starter solenoid not disengaging all the way and it is touching the flex plate.
not a whole lot things it could be and certainly doesn't sound very serious, if it is the ac pump that it not a cheap fix but that is just the way things go sometimes.

On that new of a vehicle do the fans come on and stay on and run right from the get go with the defrost on? I know they likely do come on and stay on when engine is hot enough or if the a/c is turned on but am unsure about that if the defrost is on. I ask because I never got to work on a 2015 vehicle in my shops because I was gone from the shops by 2009-2010. Thanks

 

[Doubeleive]

On that new of a vehicle do the fans come on and stay on and run right from the get go with the defrost on? I know they likely do come on and stay on when engine is hot enough or if the a/c is turned on but am unsure about that if the defrost is on. I ask because I never got to work on a 2015 vehicle in my shops because I was gone from the shops by 2009-2010. Thanks

I haven't ever checked on my Silverado which is the same thing, the fans are direct drive though not like the previous generations, there could be something came loose and is hitting on the fan blade sounds like aluminum or plastic on plastic whatever it is.