[s-cars] S6 pinging woes - the continuation

Wed Jul 29 07:42:48 PDT 2009

Not when you're wrenching from behind a keyboard, Dave!

Sent via BlackBerry by AT&T

-----Original Message-----
From: djdawson2 at aol.com

Date: Wed, 29 Jul 2009 10:39:12 
To: <pmische at comcast.net>; <dkase at dorma-usa.com>; <iduff at comcast.net>
Cc: <Vittorio.Bares at nuance.com>; <s-car-list at audifans.com>
Subject: Re: [s-cars] S6 pinging woes - the continuation

 Not to beat a dead horse, but I think you're over complicating things.? The valve seats, the guides, the rings... these are not in question here... and none of them would cause the pinging symptom.? A compression test is not useless, it will identify a major issue WAY faster than a leakdown test.

Leakdown is overkill and takes a lot more time.

Dave

-----Original Message-----
From: pmische <pmische at comcast.net>
To: 'David Kase' <dkase at dorma-usa.com>; 'Ian Duff' <iduff at comcast.net>
Cc: 'Bares, Vittorio' <Vittorio.Bares at nuance.com>; s-car-list at audifans.com
Sent: Wed, Jul 29, 2009 8:24 am
Subject: Re: [s-cars] S6 pinging woes - the continuation

Rings seat better when the engine's warm; otherwise the leakdown results are
pretty much the same.  Another variable is when valve guides are bad the
valves may seat differently every time they cycle.  

In this case I'd do the leakdown cold after spinning the engine a few times.
If there was a lot of blow-by past the rings I might be tempted to warm it
up, but things might just get worse; if it's coming apart anyway that may
not matter.

PJM 

-----Original Message-----
From: David Kase [mailto:dkase at dorma-usa.com] 
Sent: Wednesday, July 29, 2009 10:10 AM
To: Ian Duff; pmische at comcast.net
Cc: Bares, Vittorio; s-car-list at audifans.com
Subject: RE: [s-cars] S6 pinging woes - the continuation

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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