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

[Dave Saad]

I thought that was weird too - why go to so much effort to develop  
the Alusil PT only to switch back to Nikasil? Especially when Nikasil  
has such a problem with high sulphur fuels and as far as I know,  
Alusil has no problem with it.

Dave



On Apr 19, 2008, at 7:44 PM, Scott Simmons wrote:
> PT is Alusil, ABH is Nikasil?  I thought only the Bavarians used  
> Nikasil.
>
> ~Scott S.
>
> Bastian Homburg wrote:
>
>> 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
>>>
>>>
>>>
>>>
>>
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>
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