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scratchy/metallic noise at high revs

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    scratchy/metallic noise at high revs

    hey all,

    My 316i (M40 engine) has recently been causing me some stress, it seems (once warmed up obviously) when taking the car from 4k rpm up til redline there seems to be a bit of a hard sounding scratchy kinda noise, hard to describe, quite metallic, doesnt sound very healthy at all. Any ideas as to what this could be? Oil is fine, car is in general good tune, apart from spark plugs (havent changed them yet, but they looked ok last time i checked), so any ideas? doesnt seem to do it below 4k or so, occasionally 3-4 range, and it doesnt seem to matter much, but its more distinct under heavy acceleration...
    It also does this under load and also when just free revving..
    it still seems to drive how it used to, just now it sounds really bad over 4k, doesnt seem to have lost any power either, just the noise, its really hard as to explain, it almost sounds like when i boot it and it gets going, its kinda like its 'biting' and instead of it being a more throaty sound its much more metallic and whiney-ish..

    i hope that somewhere here can shed some light for me!!! Ive also checked drivebelts which were quite slack so i retensioned them and it hasnt fixed the noise...so im stumped..

    pleaaase any ideas are much appreciated!

    Thanks in advance

    Guy

    #2
    Are you sure it isn't the heatshielding of the exhaust? I had a noise that would sound like ice in a blender at about 3500 rpms. It ended up being the sheet metal heatshielding on my cat.
    Originally posted by Gruelius
    and i do not know what bugg brakes are.

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      #3
      As far as I know is the M40b16 identic to the M40b18 engine except the crank-shaft
      maybe some cam issues

      1989 E30 318iS_______________________________1989 E30 325iC M-Technic I
      1997 E36 328iT
      1990 E30 325iT 24v SOLD
      1989 E30 325i 2.7i M-Technic II SOLD

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        #4
        Do you know what pinging/detonation sounds like??

        Does your noise sound like rocks in the engine?
        Dan
        1989 325i 5-speed

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