Mystery Noise - Ram Promaster Forum
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post #1 of 7 Old 04-15-2019, 04:38 PM Thread Starter
SteveSS
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Mystery Noise

Our gas PM has developed an intermittent low-frequency buzz, sort of like metal vibrating. It seems to be coming from the engine area. It mainly happens under load with light throttle. It goes away when you take your foot off the gas, or give it more gas. Anyone recognize this, or have ideas?

SteveSS
2017 3500 159 EXT gas, silver metallic. Shiny's build thread
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post #2 of 7 Old 04-15-2019, 07:10 PM
travelvanvan
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Quote:
Originally Posted by SteveSS View Post
Our gas PM has developed an intermittent low-frequency buzz, sort of like metal vibrating. It seems to be coming from the engine area. It mainly happens under load with light throttle. It goes away when you take your foot off the gas, or give it more gas. Anyone recognize this, or have ideas?
Can you replicate it when stationary and revving? Or must you be on the road?

I have yet another kooky idea which I haven't tried because there hasn't yet been a need for it: get a device that can accept a microphone and that you can listen to what the mike "hears" via headphones. Now move the mike around until the sound gets louder. Where it's loudest is where the sound comes from. However, you can't do it while driving...

The reason I thought of this is actually PM-related. There was a fellow who had a PM and the rear springs squeaked like crazy. The dealer couldn't pinpoint it. If I remember, the dealer fought him on it, claiming it's "normal". I think the owner eventually posted a video on twitter and that might have got him the attention needed to get things going on the warranty repair. --a literal "squeaky wheel" scenario!

I feel that my technique could zero in on the location *exactly*. Because the sound level as heard by the mic would go through the roof as you got near the source of it.

[My guess for the squeaky spring guy was a spring bushing but it's hard to nail down the location because sounds reverberate everywhere.]

The reason I haven't needed to do this yet is that my PM's springs don't squeak--yet. But I think I heard them start to squeak just once. But it's not doing it right now.

As for devices to do this, I think higher end cameras with mic inputs could work, video cameras too if you've got one. Wondering out loud, maybe even 2 cell phones. Call one from the other and use that other one as a microphone that you can wave around.

Ordered Feb 2018, arrived Sept 2018. 159-inch WB regular length, high top, 3.6L gas, both driver's and passenger-side sliding doors. Planning to lightly camper-ize it for spontaneous and free-spirited travel!

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post #3 of 7 Old 04-15-2019, 07:38 PM
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Have a similar noise and pretty much think it's the cabin air filter . Only notice when first starting off and after it gets down the road warmed up a while it's gone . I put a piece of cardboard shim on about the middle top section and til it fell out the noise wasn't there . When I go to replace the filter I'm going to find someway to tighten it up . Worth a shot !

201(6) 7 Winnebago Trend
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post #4 of 7 Old 04-15-2019, 07:53 PM Thread Starter
SteveSS
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Originally Posted by travelvanvan View Post
Can you replicate it when stationary and revving? Or must you be on the road?
It only happens while moving and under light load (the engine is straining some). It often does it immediately after a shift, but it usually stops quickly. However, if I keep a light foot on the pedal, I can sometimes keep it going.


Pappy T, it does seem to be worse when cold. I'll try securing the cabin filter. Thanks!

SteveSS
2017 3500 159 EXT gas, silver metallic. Shiny's build thread

Last edited by SteveSS; 04-15-2019 at 07:57 PM.
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post #5 of 7 Old 05-05-2019, 09:26 AM
angrymountainbiker
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There are a couple of heat shields, they are poorly attached on most cars. My Tacoma had one that came off and was trapped between the frame and floor, buzzed just like you said. On the PM I think there are one or two under the passenger cabin? Worth checking.

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post #6 of 7 Old 05-08-2019, 08:36 AM
Mack
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I was looking to get this to find a mystery noise coming from the rear left corner that 2 shops couldn't find. I always thought it was a faulty shock, and I replaced them and noise gone. I was willing to pay someone $100 to find the rattle, so at just over $100 I was going to go this route. There are youtube videos that show it in action. Hope you find it, as the little noises can drive you crazy.






2017 2500 159" High Roof Gasser
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post #7 of 7 Old 05-23-2019, 10:52 AM Thread Starter
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*** Mystery SOLVED ***

It turned out to be my fault. One of the things I did to stop windshield cowl leakage was attach a plastic funnel to the end of that metal tab above the engine directly below the cowl seam. The funnel is supposed to direct dips away from the engine, but it's bottom (pointy) end was resting on the side of the intake manifold. It was picking up engine vibrations and acting like a trumpet. I zip-tied it to the rad housing and no more noise. Anytime something goes wrong right after I've been messing with something, I should know by now to suspect that first.

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2017 3500 159 EXT gas, silver metallic. Shiny's build thread
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