Strange Noise in engine compartment

SitKneelBend · Nov 1, 2015

Over the past week I've noticed a strange noise coming from the engine bay. It sounds like it's coming from the intake manifold area. I first noticed it after coming out to my truck after it had been parked for an hour.

I next heard it tonight after a short 5 minute trip and it was happening while the truck was running. I turned the truck off, the noise continued and I made this recording of the sound.

https://youtu.be/iGuOJdHfCZg

Any thoughts? I'm completely unaware of what this is and my best guess would be something to do with the fuel injection on my 3.6L Pentastar.

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SitKneelBend · Nov 2, 2015

Anybody....? Speculation is welcome. I have the recording, now I need something to tell the dealership when I take it in and show them the video for motivation.

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Hemi395 · Nov 2, 2015

My wife's 2014 Nissan Rogue (new body style) makes this same kind of noise. Almost like a tire losing air for a second or two. I brought it to the Nissan dealer and they couldn't duplicate the sound. I know its not a Ram or even a Chrysler product but from what I can tell from your video, it sounds exactly the same as the Rogue.

SitKneelBend · Nov 2, 2015

Hemi395 said:
My wife's 2014 Nissan Rogue (new body style) makes this same kind of noise. Almost like a tire losing air for a second or two. I brought it to the Nissan dealer and they couldn't duplicate the sound. I know its not a Ram or even a Chrysler product but from what I can tell from your video, it sounds exactly the same as the Rogue.

Thanks, anything helps. This is exactly the kind of situation I want to avoid at my dealership...I want to make one trip if possible.

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RCFiddyOne · Nov 2, 2015

What the heck was that? I saw the video and I have no idea what that sound is. Wouldn't hurt to take it to the dealer just to be sure. At least you recorded it and can play it back for them vs. trying to describe it and having the shop guys look at you like you are crazy.

Hemi395 · Nov 2, 2015

Sorry I know that doesn't really help explain what it is but we've had the Rogue for almost 2 years now and whatever it is doesn't seem to be hurting anything. Just scared the **** out of me when I was washing it one day I thought a tire was leaking...

SitKneelBend · Nov 2, 2015

As I said, I'm stumped and I think the dealer may be too so any input (especially from the first to respond) is welcome.

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SitKneelBend · Nov 2, 2015

RCFiddyOne said:
What the heck was that? I saw the video and I have no idea what that sound is. Wouldn't hurt to take it to the dealer just to be sure. At least you recorded it and can play it back for them vs. trying to describe it and having the shop guys look at you like you are crazy.

I figured I would go armed with knowledge and or educated guesses from this forum. I have 3 recalls sitting in the glove box so I'd like to have it all resolved at once.

The only thing I can compare this sound to is it kinda sounds (to me) like how my 99 Ram Sport sounded just before starting when the fuel pump would pressurize. The difference being that on my old truck that sound was in or around the tank under the truck and this sound definitely seems like its coming from the upper engine.

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SitKneelBend · Nov 6, 2015

Bump...

Anyone else? I have an all day appointment on Friday the 13th so I really need firepower at the dealer on such an unlucky day!

bigfoot2219 · Nov 6, 2015

SitKneelBend said:
Bump...

Anyone else? I have an all day appointment on Friday the 13th so I really need firepower at the dealer on such an unlucky day!

Your ammo, you have all the eyes of the Ram forum watching the outcome of the diagnosis and repair, none of us have your noise. So if they want to claim it's normal you can say the whole online Ramily will be boycotting your dealership and actively persuading future customers from purchasing from them.

SitKneelBend · Nov 6, 2015

bigfoot2219 said:
Your ammo, you have all the eyes of the Ram forum watching the outcome of the diagnosis and repair, none of us have your noise. So if they want to claim it's normal you can say the whole online Ramily will be boycotting your dealership and actively persuading future customers from purchasing from them.

A uniquely interesting response...fair enough.

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GP4L · Nov 6, 2015

Is it just me, or did that sound last exactly 3 seconds, then nothing for 5 and then come back for another 3...?

SitKneelBend · Nov 6, 2015

Exactly like that...it is very consistent.

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GP4L · Nov 6, 2015

SitKneelBend said:
Exactly like that...it is very consistent.

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Could be the secondary air pump running? Does the Pentastar have one of those?

SitKneelBend · Nov 6, 2015

GP4L said:
Could be the secondary air pump running? Does the Pentastar have one of those?

I'm not aware of any air pumps at all. What is its function? I'm not familiar with the nomenclature...

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GP4L · Nov 6, 2015

SitKneelBend said:
I'm not aware of any air pumps at all. What is its function? I'm not familiar with the nomenclature...

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Typically, they only run for ~30 seconds during a cold start. They literally pump air into the exhaust manifold (or directly into the exhaust port, through a passageway in the cylinder head) to lower emissions during startup (combustion efficiency is very bad when the engine is cold, so higher amounts of un-burned fuel leaves the cylinders).

My guess was based on the fact that whatever that noise is - it seems like it's very intentional/normal. But I don't know anything about the emissions controls for the Pentastar engines, so I shouldn't speculate too much.

SitKneelBend · Nov 6, 2015

GP4L said:
Typically, they only run for ~30 seconds during a cold start. They literally pump air into the exhaust manifold (or directly into the exhaust port, through a passageway in the cylinder head) to lower emissions during startup (combustion efficiency is very bad when the engine is cold, so higher amounts of un-burned fuel leaves the cylinders).

My guess was based on the fact that whatever that noise is - it seems like it's very intentional/normal. But I don't know anything about the emissions controls for the Pentastar engines, so I shouldn't speculate too much.

Ah I see, I have the same thing on my motorcycle except it's called an air induction system (AIS). I didn't know they used these on trucks too.

The noise definitely sounds like it's coming from the engine, but from my observations appears to be centered around the intake manifold. I was under the impression that AISs pump Air into exhaust to aid in the combustion of unburnt fuel.

Maybe someone with more knowledge than me on the Pentastar can chime in and let us know if these engines are equipped with this system.

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Strange Noise in engine compartment

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