[s-cars] S6 pinging woes - the continuation

Thu Aug 13 19:31:08 PDT 2009

U da man!!

Take a look here:
http://picasaweb.google.com/BlissRally/95S6HeadGasket?authkey=Gv1sRgCLTZ
_KHcwtL9bA#
<http://picasaweb.google.com/BlissRally/95S6HeadGasket?authkey=Gv1sRgCLT
Z_KHcwtL9bA> 

Now - couple of questions:

1.	the block - you can see in the pic the burn mark - any reason to
believe this will create more issues with a new gasket?
2.	the head - not nearly as noticeable burn mark - I would think
this would be fine.
3.	Pistons have some slop, I understand I can check this with a
feeler gauge? Anyone know the spec on it?

And finally, what causes this?

Thanks,

Vittorio -

________________________________

From: djdawson2 at aol.com [mailto:djdawson2 at aol.com] 
Sent: Sunday, August 02, 2009 12:36 AM
To: Bares, Vittorio; t44tqtro at gmail.com; s-car-list at audifans.com
Subject: Re: [s-cars] S6 pinging woes - the continuation

Who's your daddy?  Who made the call?

Seriously, pull the head and take a good long look at the cylinder head
material between 4 and 5... make sure there isn't a groove burnt in it.
Also, take a very close look at the top of your #5 piston to make sure
that part of it isn't missing from the detonation.

If you're lucky, you will only find that the headgasket material is gone
between the cylinders.

BTW, you're not losing coolant, finding it in the oil, or blowing smoke
because your gasket is blown between cylinders, not between a cylinder
and the water jacket or oil passage.

Good luck.

Dave

-----Original Message-----
From: Bares, Vittorio <Vittorio.Bares at nuance.com>
To: djdawson2 at aol.com; t44tqtro at gmail.com; s-car-list at audifans.com
Sent: Sat, Aug 1, 2009 8:42 pm
Subject: RE: [s-cars] S6 pinging woes - the continuation

Ok -

Compression Test (cold motor):

#1 155

#2 145

#3 125

#4 50

#5 60

Leakdown (warm motor)

#1 13%

#2 20%

#3 50%

#4 Near 100%

#5 Near 100%

When applying air pressure to #3, some air coming out of #4

When applying air pressure to #4, lots of air coming out of #5

When applying air pressure to #5, lots of air coming out of #4

So, head is going to need to come off - I'm just surprised I'm not:

a) eating *more* coolant than I am

b) have water in the oil, or oil in coolant

c) blowing billowing clouds of something from the tail pipe

Anyway, I'm hoping that I can just take the head off, replace the

headgasket (I have a metal one I can put on) and put it back on. Seems

to make sense to put some ARP studs in there - this is all best case

scenario - I guess I'll know more once the head comes off...

Comments?

Vittorio -

-----Original Message-----

From: s-car-list-bounces at audifans.com

[mailto:s-car-list-bounces at audifans.com
<mailto:s-car-list-bounces at audifans.com?> ] On Behalf Of
djdawson2 at aol.com

Sent: Tuesday, July 28, 2009 1:00 PM

To: t44tqtro at gmail.com; s-car-list at audifans.com

Subject: Re: [s-cars] S6 pinging woes - the continuation

 I believe that 30 minutes with a cheapo compression gauge is going to

give the answer... call it pre-ignition or detonation.

There are many documented cases of headgasket failure between 2 adjacent

cylinders.? The headgasket fails, then it burns a little groove in the

cylinder head between those 2 cylinders... allowing flame travel...

BTDT.

The one I experienced was between 4 and 5.? 5 was being pre-ignited.?

The result was an engine that sounded like it was "pinging" under any

and all conditions, even idle.

Letting this go for too long will result in total failure of a piston.

I would urge you to do a compression test before doing anything else.

Dave

-----Original Message-----

From: Taka Mizutani <t44tqtro at gmail.com>

To: s-car-list at audifans.com

Sent: Tue, Jul 28, 2009 10:50 am

Subject: Re: [s-cars] S6 pinging woes - the continuation

You've just contradicted yourself, Brett- if the fuel/air charge ignites

prematurely, you get a large increase in cylinder pressure, which causes

all

sorts of bad things to happen to the engine.

You've stated this below as well as stating that it doesn't.

Anyway, the bottom line is that it's bad, the OP may have damaged

his/her

engine and it should be checked out. Having that happen with all of the

high

boost mods taken out is a bad sign.

I'd also check the fuel system to make sure that you're getting the

proper

amount of fuel actually delivered- if the pump or FPR or injectors are

not

doing their jobs, the computer might think it's sending enough fuel when

it's not.

Taka

On Tue, Jul 28, 2009 at 11:48 AM, Brett Dikeman

<brett.dikeman at gmail.com>wrote:

>

> Pre-ignition does not increase cylinder pressures and temperatures

> much beyond normal values (I think).  Pre-ignition is bad because it

> puts more force on the engine internals, and in ways it wasn't

> designed...for example, if power is developed at exactly TDC, all the

> force goes against the rod, crank, bearings, and head gasket/bolts,

> instead of applying torque on the crank.  Detonation does increase

> pressure and temperature, massively- it melts and bends things.

>

> Cody's recommendation to drain/filter the oil and check the engine oil

> filter are sound.

>

> Brett

>

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