
I'm looking for some advice.
My 406 has a noise that occurs any time that i rev the engine above 3000rpm.
> It's more noticeable under load/acceleration, and goes quiet if i lift off the accelerator/balance the throttle (while still above 3000rpm).
> It feels as though the power is not really as much as it should be after 3000rpm while hearing the noise.
> It is a higher pitched tapping noise, that sounds a bit like a tappet noise, or maybe a little end or a piston slap kind of sound, but definitely not like the deeper big end or mains bearing kind of knock.
> It also sounds similar to Pre ignition pinking associated with over advancement of ignition timing in petrol engines. I have a feeling that it could just be a pinking kind of symptom associated with a fueling problem of some kind that i have seen suggested on other posts about noises.....but i'm not sure what part exactly would cause these symptoms?
My 406 has the 2.2 Hdi, and has done 68k. The sound has been there since i bought it at 65k.
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Now, my beloved old 406 2.2 Hdi had the same noise and symptoms when I bought it at 132k.
When i asked my helpful 'Hdi knowledgeable MOT guy' to take it for a spin, and he returned with ideas of little end or piston slap, he just said "treat it with care, put it down to a hard life and perform a quality oil change". I subsequently changed to millers oil and changed filters etc. This did not help the noise.
The thing is, a FEW thousand miles after I preformed the oil change to millers, the noise just disappeared one day, never to be hard again !
The engine continued to sound lovely, until at 144k some twat (now known as the 'third party') pulled out in front of me and DesTroYeD my baby...


It seemed to me that too much time and mileage had been covered since the oil change, for the possibility that a noise emitted from mechanical wear could have been silenced by quality oil.....?
But if it had been a fueling problem, what could possibly cause this symptom that 1 day just disappeared?
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So, assuming these same symptoms on my current 406 are being caused by the same problem, does anyone have any advice or pointers as to a possible cause?
Or have you experienced the same symptoms and had the problem fixed?
I don't want to simply wait to see if it disappears like my old car, even if if ever would?
Many thanks guys, looking forward to some feedback
