Re: TECH:Trying to confirm rod knock (+ Suggestion)

["Ben Channard" <zeroid@hotmail.com>]

>From: chris gonzalez <chris24g@yahoo.com> wrote:

>the patient: 88 cabriolet 1.8 8v (all stock).
>the symptoms: start the car and everything sounds fine at idle. slight
>ticking from the hydraulic lifters, but nothing out of the ordinary.
>rev the car, and it still sounds normal. get it and drive the car up
>the block still normal for about 1/2 mile, then a dull knock knock
>knock that varies with engine speed. used a mechanics stethoscope and
>the sound is apparently coming from the vicinity of the oil pan/
>automatic transmission.
>
>I pulled off the oil pan and could not see anything out of the ordinary
>(with my untrained eye, that is). connecting rod bolts are all there,
>and torqued, at least...
>
>Should I go further and pull of the rod bearing caps and inspect the
>crankshaft? I figure if a rod is knocking it's "gonna leave a mark."

                      ***********************************
Chris:

     I can't directly address your problem but the volks.net site has .wav 
files of sounds to help diagnose air-cooled VW problems.  These were 
apparently from a tape which was produced by John Muir of "How to Keep Your 
Volkswagen Alive" fame.  The home page of the site:

<http://www.volks.net/index.htm>

Then click on "Muir Engine Sounds"  Then go down to Engine Noises and "Loose 
Connecting Rod"  Here is the direct link:

<http://www.volks.net/sounds/muir/looserod.wav>

And the accompanying description: Loose Connecting Rod (202 KB) - 
Alternately rev and back off engine. Listen for the "rattlesnake song" of 
the loose rod. The rod knock noise flutters in and out.

Now I have a few questions.  Is this really what "rod knock" sounds like?  
And is there anywhere that has similar sound files for our water-cooled 
cars?  If we recorded mystery sounds, could we put them up on scirocco.org 
as a troubleshooting resource?

                      ***********************************

>Has anyone used the "ground out the spark wire trick"?

So, how does this work?  Please enlighten us.  Thanks and HTH, benton-----


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