[s-cars] Warped Head Symptoms?

[Tony Curran]

Dave,

 

Thanks for the info. It very well could be #1. I've not experienced any "odd
pinging". And I believe #2 was more common in pre-95 cars as Audi went with
a newer gasket design for 95.5 and up - but I may be wrong.

 

This issue occurred when out air temp was -27deg C. After replacing t-stat
ran the car for nearly an hour (air temp was -4deg C). Ran at idle for a
while then drove around a bit. Both fans were working OK and no excessive
coolant temp or pressure. Will keep an eye on it though. Local mechanic has
been advised it may be in the shop soon - he drives a 911 but previously
owned a S4.

 

Thanks again.

 

Tony

 

From: djdawson2 at aol.com [mailto:djdawson2 at aol.com] 
Sent: January-05-14 4:08 AM
To: tony.curran at sympatico.ca; s-car-list at audifans.com
Subject: Re: [s-cars] Warped Head Symptoms?

 

If your head is warped, there will be only one symptom, and that will be
eventual head gasket failure.

In 20v Audi engines, I've experienced headgasket failures of just 2 types:

- #1 Blown between a cylinder and the cooling jacket.  This often results in
blowing the seal between the plastic ends caps and the aluminum radiator
core, blowing off the coolant res cap, blowing your heater core, etc...
This version of headgasket failure is relatively harmless in the big picture
- symptom is simply excessive cooling system pressure.  Fail to grasp what
is going on, and you'll just be replacing each weak link in your cooling
system, one at a time, that succumbs to the excess pressure.

- #2 Blown between cylinders 4 and 5.  This results in a cross ignition
situation.  Cylinder 4 fires right before 5 (1-2-4-5-3).  When 4 fires, the
flame travels across to cylinder 5, preigniting it.  Result is losing a lot
of aluminum from the head between the cylinders, and a destroyed #5
piston/cylinder resulting from preignition and detonation.  Fail to
recognize this situation quickly, is costly... you can pretty much count on
having to replace the block and head assemblies.  If your car EVER starts to
sound like it's "pinging" all the time, even at idle, a headgasket blown
between 4 and 5 is the likely culprit.  If you catch it fast, you'll be very
glad you did.  Fail to - get out your wallet.

Back to your t-stat.  I'm sure there are stories of t-stats failing closed
that someone can and probably will tell us.  But in my 30-ish years of
dozens of Audi/VW/BMW cars, I have yet to personally experience a t-stat
that failed in the closed position.  EVERY t-stat failure I've ever had
became evident as soon as it got cold out.  They would fail in the open
position, and in cold weather the engine would run too cool, and provide
poor heat.  My point?  There are a number of reasons you could have blown
your coolant.  However, I seriously doubt it was because of your t-stat.  I
would first check to make sure your fans are coming on, etc... to insure the
car isn't overheating in general.  All the while, I'd be wary of any signs
that the real issue is pressure being leaked into the cooling system from
combustion.

hth

Dave

 

 

 

-----Original Message-----
From: Tony Curran <tony.curran at sympatico.ca>
To: S-Car-List at Audifans.Com <s-car-list at audifans.com>
Sent: Sun, Jan 5, 2014 1:26 am
Subject: [s-cars] Warped Head Symptoms?

Hi All,
 
 
 
On another thread there was mention of loss of coolant and possible warping
of the head due to overheating.
 
 
 
My S6 experienced loss of coolant recently - blew it out through the
overflow tank cap. It appears that the thermostat was the culprit. There
were no telltale head gasket failure signs.
 
 
 
So, if the engine did overheat sufficiently to warp the head, what would the
symptoms be?
 
 
 
Also, when I ordered thermostat from local online source, this is the part
that arrived.
 
 
 
http://www.calorstatbyvernet.fr/CATALOGUE/Accueil/IBEAALTHSnpGUkN0aVVUSHRFAA
A?A8
 
 
 
It is somewhat different to the Wahler brand.
 
 
 
TIA
 
 
 
Tony
 
96 S6
 
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