[s-cars] S6 pinging woes - the continuation

Sun Aug 2 06:50:45 PDT 2009

When this happened to my WX 10 valve, it was sudden and only driving along about 30 mph under no boost. It didn't sound like it was pinging, it just felt like it dropped a cylinder. I limped the car home very gently (No boost)- only about 3 miles, and shut it off. My computer crashed recently and I lost the photos, but the head had a passage burned in it from cylinders 4-5 that was about 1/2" wide and 3/16" deep.
I hope you're more fortunate.
Dawson - I think you called mine as well.

Dennis 
Denver

-----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] 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 ign
ites
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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