[V8] Well, it's spring....

[Bastian Homburg]

um....let me explain:
The ABH (4.2) and  PT (3.6) motor were assembled using different 
technology:  With the small motor, they used some kind of etching 
process whereas the 4.2 used nikasil coated cylinder walls. And exactly 
this coating is washed off over time due to a chemical reaction with 
sulphur components found in gasoline. That is why most of the ABHs use 
lots of oil even when the rings are perfectly OK. This is worse in 
manual trans models, which are geared shorter and tend(ed) to be driven 
more aggressively.
And only the very last V8s had R134a AC from the factory. All '92s as 
well as most of the '93s still were equipped with R12 - the switch to 
R134a was made around May 1993.
Retrofitting the system (no matter if 'old' or 'new' control unit) to 
R134a is pretty easy. Audi sells a "retrofit kit" that includes 
everything you'd need
(part no. 4A0298107A for the denso compressors in the 3.6 and 4A0298107 
for the Zexel compressors in the 4.2), plus there's even an official 
retrofit guide (see 
http://www.audiv8.com/forum/download.php?Number=92939 for a pdf 
version). Cost for this kit in Germany is 200 Euros.
The refrigerant type should definitely not be a major point in deciding 
for or against a specific V8.




Dave Saad wrote:
> On the oil consumption issue, I think a lot of 3.6L motors had the  
> same problem.  Mine sure did.  It seems that the problem is the  
> design of the oil ring - it is just bad.  I put new rings in mine and  
> oil consumption has gone down to a normal level.  My plugs now are a  
> nice brown too instead of crusted black.  I am not sure why some  
> motors seem OK while others are oil burners from the same model  
> years.  maybe the factory used two different styles of ring during  
> production?
> On the other issues, the AC is probably the biggest to me.  Having  
> the R134a would be nice just for the ease of servicing. The newer  
> control head would also be nice I suppose, but the old style works  
> well enough.
>
> Dave
>   
>