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Discussion Starter #1
Only at start and when engine is cold. Gear in P and I was gently revving the engine couple of times up to just over 1000RPM before shifting into R. I was touching nothing other than gas pedal

The whine came from engine bay passenger side. Sounded like a metal pan or something hollow was reverberating to a specific frequency. It only happened between 900-1000RPM.

Any ideas?

Could a car be designed like Sea-Tac Bridge that it can fall apart at certain harmonic frequency?
 

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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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Hi naomilla,

Two words come to mind: Heat shield.

MBL
 

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Will it continue to make this noice repeatedly?? Chances are it is a heat shield, most likeley the one surrounding the pre-cat.

Jonathan
 

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Discussion Starter #4
Since I drove by the garage I take my car for major service work (anything other than oil change and other *very* minor repairs I am capable of), I popped in and told them of the symptom. Sure enough, it was the loose heat shield. The mech recommended removing it but I just asked him to retighten it for now ('Let me think about it' was what I said).

Any adverse effect from removing the heat shield?
 

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Heat shield is to protect the transfer of heat to other locations... Duh! (J/K) Most cars can live without em, some can't...
 

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Discussion Starter #6
MasHiMarO - 2/25/2005 4:23 AM

Heat shield is to protect the transfer of heat to other locations... Duh! (J/K) Most cars can live without em, some can't...
Would you consider W126 (560SEL) to be in the former or the latter category. I wasn't sure and that's why I held off. Some time ago in this forum, one of the Canadian folks posted an experience where he went through a puddle and had loose heat shield become entangled - I don't want that to happen to me, and if the car can live without it, then I'd take it out as if it is an inflamed appendix.
 

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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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Hi again, naomilla,

In addition to shielding floor pans & various components from high exhaust temperatures, the H/shields perform another function not often recognized. Usually located upstream of, and close to both the Ox Sensor & Cat Converter, they ensure the rapid & sustained heating of those two items, thus providing more efficient operation, resulting in reduced emissions and overall smoother, more powerful engine operation.

Who knows; when tight, they may provide the added bonus of sound reduction inside the car as well? :eek:)

That said, years ago when I worked as a tech, I've removed & tossed out rattling heat shields on more than several occasions.

My 3 cents. MBL
 
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