[s-cars] S6 pinging woes - the continuation

[David Kase]

While you are searching for a somewhat major leak, you should have the
engine warm for a true reading.  If it's not a blown gasket then you
will at least have valid leak down numbers.

DBK

-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com] On Behalf Of Ian Duff
Sent: Wednesday, July 29, 2009 9:53 AM
To: pmische at comcast.net
Cc: Bares, Vittorio; <s-car-list at audifans.com>
Subject: Re: [s-cars] S6 pinging woes - the continuation

This is awesome practical advice, nice job!

-Ian Duff, sent from my iPhone.

On Jul 29, 2009, at 9:39, "pmische" <pmische at comcast.net> wrote:

> During the leakdown, vent the cooling system and the cam cover for  
> insight
> into where that air's ending up - you'll see bubbles and/or hear  
> it.  You
> can also hear leaky valves by listening at the tailpipe or inlet  
> tract.
>
> Compression tests, which I believe are next to useless, do not  
> necessarily
> correlate to leakdown tests.  Leakdown tests are much more telling.
>
> PJM
>
> -----Original Message-----
> From: s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com] On Behalf Of Bares, Vittorio
> Sent: Wednesday, July 29, 2009 9:11 AM
> To: djdawson2 at aol.com; t44tqtro at gmail.com; s-car-list at audifans.com
> Subject: Re: [s-cars] S6 pinging woes - the continuation
>
> A friend of mine is coming by tonight w/a leakdown test device - not
> nearly as quick and simple as a compression test - but I would assume
> that if there is an HG failure between cylinders, where the adjacent
> cylinder has open valves relative to the test cylinder at TDC - the
> leakdown percentage should be very high for both those cylinders.
>
> I would assume that a compression test would show low compression in
> those two cylinders also.
>
> 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  
> 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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