M20 noisey topend, not regular tapping

[OOjoeE30]

I've had my 320i a few months now and have recently finished replacing all the service items so started to open it up abit. On doing this I have noticed some topend noise so adjusted the valve clearances but the noise has persisted.
Its not your regular tapping noise but only seems to appear around 1500-2000rpm more prominently when the revs are dropping, kind of a vibrateing metallic tap.
Now I'm thinking is it a bearing or something, but the engines only on 45000.

[kam-325i]

Bearing rumble or groan, not tap.....

M20's are known to be "Tapperty". you will never completey get rid of it, unless you fit a M50 donk.

[OOjoeE30]

I need to get a video really its like a "nahhhh" noise

[kam-325i]

is the noise more prominent at the front of the engine?

[OOjoeE30]

Yes I would say so but have checked with viscous removed and for play in the waterpump

[kam-325i]

I need to get a video really its like a "nahhhh" noise

as soon as you said this.........water pump...

when was the water pump changed ?

My 320i made the same noise, took me ages to find it....

[OOjoeE30]

Originally thought it was the pump, I changed it last weekend

[OOjoeE30]

Any ideas on this its only really apparent when upto temperature, its a bit annoying as I thought the mechanics would be solid going by the milage and dont want to have to give it to a garage

[kam-325i]

Try taking off the fan belt and spin the alternator by hand......

[mcbonio]

You need to get a long metal rod and place it to your ear then onto various components of the engine to pinpoint the sound like a stethoscope.

[OOjoeE30]

Problem seems similar to this
http://www.e30zone.net/modules.php?name ... se+2000rpm

[OOjoeE30]

turned out this was the tensioner swapped to an original bmw item and the noise went it seems the old one was dragging.