[V8] Spectral analysis V8 ABH and PT blocks

[Ingo Rautenberg]

Bastian,

Jason was referring to the Positive Crankcase Ventilation system as routed on our cars. One of these days I'll have to put together a catch can system of some sort with auto-return...

Ingo Rautenberg

-----Original Message-----
From: Bastian Preindl <bastian at preindl.net>
Date: Fri, 11 Dec 2009 14:47:37 
To: Jason Wilkerson<wilke_jb at yahoo.com>
Cc: V8 list<v8 at audifans.com>
Subject: Re: [V8] Spectral analysis V8 ABH and PT blocks

Dear Jason,

what's the PCV system (shame on my head)?

In generally we say if the car smokes blue after starting the engine 
valve seals are weared out and/or the walves don't fully close any more 
(due to oil cole). When accelarating again after a time of motor 
braking, blue smoke behind you can be both: The valve seals and the 
piston rings (or the cylinders). You generate a vacuum which takes oil 
into the cylinder - from whereever preferred. But the really oil 
consuming engines as mentioned in my posting also cause blue smoke when 
strongly accelarating - e.g. on a highway. But usually those engines 
have proper valves and full, excellent compression - still they consume 
oil like hell.

You now mention the possibility of over-pressure not of the oil, but of 
the oil gases - is this correct? Can you explain this a bit further so 
that I can put this into discussion on the audiv8.com platform? It's not 
really clear to me yet what you mean. Additionally: Why are only the 
4,2er engines affected?

I can remember somebody proposing in this list that the design of the 
heads on the 4,2 are reason for oil overpressures pressing the oil into 
the combustion chamber. I also don't fully understand this reason, so if 
somebody knows what's going on, don't hesitate to make this clear to me.

Additionally something has been changed after the first series of ABH 
'cause we can (not empirically proven yet) observe that the younger the 
engine, the less the oil consumption (mostly independent from the 
mileage). A '93 ABH usually, by average, takes less oil than a '91 or 
early '92. Anybody who can agree or disagree?

Thanks

Bastian

Jason Wilkerson schrieb:
> That is some interesting info to have on the makeup of the blocks, thanks.  I always made the assumption that the oil usage was strictly because of the PCV system.  The reason I felt this was because if you look at the actual system and how it is plummed, it just makes sense.  If you go down a long hill and at the bottom you hit the gas you will see a small plume of smoke from our cars.  The reason for this is simple: one of the 'breather' hoses for the PCV is located directly above the throttle plates.  When you allow the engine to engine brake with the throttle plates closed (as in a downhill situation) you create enough vacuum to suck up oil into this hose, once you hit the throttle again it pulls it on through the motor and out the tailpipe.  I would assume this problem to be worse on a manual transmission car BTW.  
>
> --- On Fri, 12/11/09, Bastian Preindl <bastian at preindl.net> wrote:
>
>   

_______________________________________________
Audifans V8 mailing list
Send posts to: mailto:V8 at audifans.com
Manage your list connection: http://www.audifans.com/mailman/listinfo/v8

You can help keep the audifans site running by shopping at http://audifans.com/shop/