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In cabin rattling/ metallic noise around 2800 RPM

rob001

Well-known member
Joined
13 Jan 2011
Messages
132
My friends 997 4s manual is making in any gear but best heard in 3rd around 2800 rpm a rattling, buzzing, metallic noise very noticeable in cabin coming from left side rear. The noise is only under a very light load/ feathering the throttle around 2800 rpm. Putting more load or WOT, no noise

Listening outside and on bridge in neutral impossible to pinpoint location.
Also difficult to say if the noise is internal or external.

Since the noise sounds typical like a loose heat shield, cat, exhaust and to rule out the usual suspects we changed out both exhaust, cats, heat shields, drove without belt, without rear bumper, checked all coolant, AC and fuel lines etc.

Some history to this, engine was dropped to replace coolant and rear break lines, changed plugs etc.

When using PIWIS and actuate the valve lift at around 2800 RPM almost same noise can be reproduced in neutral. Changed the solenoids and did not helped.
 
Sound clip if possible by someone sitting in the back of the car and moving the phone around when the nise is there might help .

Couple of things to check ..

Make sure all the cross braces are done up very tight .

check and reposition the engine earth lead .. i remember some bulletin about it causing noises when it touched the cam cover .

Check ALL pipes .. anything touching engine say a metal coolant pipe will transfer noises to the cabin .

i think the 2800 is just the required frequency of this vibration and not really the high lift activation .. that kicks in at about 3k - 3100 .

I assume this started after the engine drop ?
 
Hi DeMort, thanks for fast reply. The noise started a week after the engine drop. Tempting do drop again and double check everything!
 
Focus on what was removed is what i would do so Any fixing removed .. brace bars etc and Any pipe or cabling .. something is providing a Hard connection from the engine to the body imho.
 
Corroded heat shields maybe?
 
It could well be his water pump. I noticed a metal whirring noise a week ago, all of a sudden and coolant started leaking. A new pump and all was back to normal. The bearings in my pump had failed. Remember that a failed unit, doesn't always include the coolant leaking.
 

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