[V8] Engine rebuild options

[QSHIPQ at aol.com]

I rebuilt the heads on Ingo's 5spd car, and that didn't help either (maybe  
70k at the time).  I'm pretty convinced this oil sloshing is the main  culprit. 
 My ex rarely stabs the pedal hard, and her oil PT oil consumption  is nil.  
Oil in combustion is a bad thing, since oil doesn't burn it really  creates 
hot spots (like at piston rings)...  Add in a lot of timing advance  it gets 
worse.  Add in the MAF doesn't like to be coated in oil either, you  have a bad 
fuel mixture during and after your run to boot.  This can take  out a motor 
fairly quickly after a rebuild.
 
IME, the manual cars really slosh that oil, as to cars with suspension  mods. 
 The AAN 20vt motor has the same sloshing problem.  I really  think that Audi 
just didn't take the time in the 1980'2 and 1990's to address  this design 
correctly.  The best place for PCV is dead center in the  head.  This avoids 
sloshing front or rear mounted vent ports.
 
I also suspect that the cylinder walls (however they are constructed) don't  
take well to all this abuse either.
 
HTH and my .02
 
Scott J
In a message dated 8/27/2008 7:01:02 A.M. Central Daylight Time,  
tonyandlillie1 at earthlink.net writes:

I do  know of two that have rebuilt heads, and it didn't help. And mine, 
which  smokes pretty badly on long deceleration, doesn't burn anything  
appreciably. BTW, that shows it's the heads, not the rings. Generally,  smoke 
on acceleration is rings, smoke on decel or at idle is the valve  
guides/seals.

However, I think there's something to Scott's theory  about venting the heads 
at the back. I guess if every acceleration is a  hard one, pushing the oil 
inot the venting system could lead to a  problem.

That is pretty bad oil consumption on those ABH's. Just out of  curiosity, is 
it worse on manual transmission models? That seems to be one  thing I see 
here. And, that would also support the venting theory, as they  have the 
ability to accelerate much harder than the automatic  models.

Tony

>
> well, the PT engines may also take  more oil in the years (I talk about 1 
> or 1,5 litres on 1000 km) but  it usually helps to overhaul the heads 
> (whereby mainly the valve stem  seal is worn out)
> and it lowers oil consumption quite reliably and  significantly. Doing the 
> same on an ABH (and we're talking about  amounts >3l/1000km, which we had 
> on dozens, if not hundred  machines in the forum over the years, not 
> directly connected to the  mileage) usually doesn't help a lot - the 
> consumption remains,  whereby the compression is perfect. The assumption 
> that the reason  for this are problems with the cylinder coating is a 
> consequence -  whereas somebody came up with the NiKaSil theory (stated as 
> a fact,  sincerely). So if it's not about NiKaSil, I wonder what's the 
> reason  and why the ABH, mainly the older ones, take significantly more oil 
>  than the PTs. There has to be a reason.
>
> If it's about  overheating, what I personally experienced also (I had once 
> an early  '92 ABH with 240tkm on the engine and it significantly raised the 
> oil  consumption (well, from 1,5 to 2,5 or even more) after it overheated 
>  once due to a fluid leakage in mid summer) but didn't interconnect at that 
 
> time, what engine parts are impacted by the overheating and how can  it be 
> repaired?
>
> Bastian 


 



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