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Re: Onomatopoeias - was: Source for lifters/valves?

> Either we are not being consistant with the use of our onomatopoeias or we
> could be describing different noises.  Frankly, the one I'm most concerned
> with is the CLANK...CLANK...CLANK  I hear under the hood on cold morning at
> startup.  It usually goes away when I rev the engine to 1800rpm or so.  The
> sound wasn't present in the  summer months. In fact I haven't heard it since
> early last spring.  This clank sounds more like a loose rod bearing; but, if
> it were why only on cold stary ups in the winter ....

Ticking noise on cold startup that disappears after a few seconds or minutes
is usually caused by the delay in getting engine oil from the pan at the
bottom of the engine pumped to the hydraulic lifters and cams, etc. Use of
an Audi* oil filter with an anti-drain-back valve will generally eliminate
or reduce this problem considerably. An oil filter of this type prevents
the oil from draining back into the pan from the oil passages above the
pump and filter; result - the oil gets to the lifters much sooner.

Cold weather aggravates this problem due to the fact that colder oil is
generally more viscous and is harder to pump. Solution is to use the right
viscosity grade for the weather. Better still, use synthetic oil which
has much better cold flow and pumpability characteristics than fossil oil.

Revving the engine pumps the oil faster so you see the noise stopping
earlier. Its generally not a good idea to rev a cold engine; wears out
parts since the oil hasn't reached them yet.

* - OEM quality replacement filters from reputable manufacturers like
Mahle, Knecht and Mann are just as good but cheaper than buying from Audi.


Zafer Mehmood				   AT&T Bell Laboratories
zm@mhcnet.att.com			   Murray Hill, NJ