[s-cars] Knocking developed while on highway

[dgraber460 at aol.com]

FWIW I seriously thought I threw a rod when my AC compressor went toes up. Backing out of the driveway, and it started knocking just like a rod bearing. Pull the AC relay to confirm. One can hope.


Dennis Graber
Quality Linings & Painting
Denver, CO


-----Original Message-----
From: Tom Green <trgreen at comcast.net>
To: s-car-list <s-car-list at audifans.com>; Azeem Elahi <azeem.elahi at gmail.com>
Sent: Wed, 7 May 2008 8:11 am
Subject: Re: [s-cars] Knocking developed while on highway



Wow, real answer is I don't know, so you can ignore the rest if you  
like.

I guess a quick engine burp could rotate the engine on bad motor mounts
enough to tear the intake hose.  Otherwise, I would think you would  
have had
other indications if the hose was torn for a while, i.e., MIL or miss/ 
jerk on
acceleration.  But what could cause such movement to tear the hose?    
Look
under the upper timing belt cover to check for any visual damage.    
If you
see anything suspect, I wouldn't turn the engine over any more until  
you can
confirm it's ok, and valve sprockets and crank/flywheel marks align  
at TDC.

I read that you have the knocking noise at idle and hear it just  
looking under
the hood?  Check the hydraulic fluid level, since the pumps are known  
to be
noisy (knocking sound) especially when low on fluid.  It, or another  
accessory
could be failing (alternator, A/C compressor, or water pump) and can  
put such
a load on the engine that it appears to be a miss.  Check condition  
of the
serpentine belt for any excessive wear.  A long screwdriver (plastic  
end to the
ear) or mechanics stethoscope can help isolate the noise source if  
you don't
find any visual indications.

  You will want to check for DTCs and clear them also.  Oil from the  
crankcase
vent system will deteriorate the intake hose and cause it to crack at  
the clamp,
so this part may just be a common issue.

Tom

> Date: Tue, 6 May 2008 17:58:05 -0500
> From: "Azeem Elahi" <azeem.elahi at gmail.com>
> Subject: [s-cars] Knocking developed while on highway.
> To: s-car-list <s-car-list at audifans.com>
> Message-ID:
>   <c35bfa520805061558n4b44f96cne4afd7978271f09f at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Need some help guys.  As I was driving home from work in my '95 S6, I
> noticed a slight miss/hesitation for 1 second which was quickly  
> followed by
> knocking from the engine cabin. I immediately pulled over and gave  
> it a good
> listen to make sure of the source, and it does indeed seem to be  
> coming from
> within the engine.  I also noticed the turbo inlet hose has tore  
> off (the
> hose that goes from the intake to the turbo).  Car was driving  
> perfectly
> before hand, and always had regular oil changes.  Oil level is  
> perfect, no
> smoke out the tailpipe.  What the heck could have happened here?!?

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