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

[OR VietVet]

Yea, it is a weird noise but is loud enough and stays on long enough that the source should be easy to find.

I have a noise on start up when the outside temp is close to freezing or below and I do a cold start and the noise is very faint and sounds like a small amount of air being released at the blow up nipple on a balloon when is not tied off but that nipple is pulled/stretched sideways and releasing air. Goes away in 2-3 seconds. If is at 35 degrees or warmer, there is no noise. My belts, idlers, tensioners are all recently new and fans are not spinning.

 

[Doubeleive]

Yea, it is a weird noise but is loud enough and stays on long enough that the source should be easy to find.

I have a noise on start up when the outside temp is close to freezing or below and I do a cold start and the noise is very faint and sounds like a small amount of air being released at the blow up nipple on a balloon when is not tied off but that nipple is pulled/stretched sideways and releasing air. Goes away in 2-3 seconds. If is at 35 degrees or warmer, there is no noise. My belts, idlers, tensioners are all recently new and fans are not spinning.

I would do the same thing then take the belts off before that 1st cold start and see if it is a accessory or not, process of elimination

 

[OR VietVet]

I immediately thought of that but here in the PNW, getting close to freezing is a very rare occurrence. In the last 1 1/2 months I have only heard the noise 3 times. I think whatever it is will have to get worse to pinpoint. I have experienced no driving or starting problems so it is just on my radar and will be listening for it. I will report back if I do find the noise.

 

[stephen sibilia]

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.

Ty Sir, I appreciate the advice. I’ll report bk.

 

[stephen sibilia]

Thanks for the advice all. I will get to work tomorrow and report back.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics, please.

The folks here have already given you lots of items to check on, and please let us know what you find out from their suggestions.

 

[stephen sibilia]

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

 

[89Suburban]

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

Please keep us updated, this is very strange indeed.

 

[Fless]

Sounds to me like a power steering pump (low on fluid?).

Can you remove the main serpentine belt and start it up cold again, to see if the noise is gone? If it is, start checking the pulleys by hand, without the truck running, of course.

 

[Doubeleive]

Sounds to me like a power steering pump (low on fluid?).

Can you remove the main serpentine belt and start it up cold again, to see if the noise is gone? If it is, start checking the pulleys by hand, without the truck running, of course.

electric steering on those, no pump