[Vwdiesel] RE: [Audi-VW-Diesels] Drilling out intake manifold on 1.6NA

[Jonbonbart at aol.com]

In a message dated 5/22/02 3:40:23 PM Eastern Daylight Time,
gmbulley at bulley-hewlett.com writes:

<< From: jon.sykes at ps.ge.com [mailto:jon.sykes at ps.ge.com]
 Sent: Thursday, May 16, 2002 7:17 PM
 To: Audi-VW-Diesels at yahoogroups.com; vwdiesel at audifans.com
 Subject: [Audi-VW-Diesels] Drilling out intake manifold on 1.6NA

 I've heard conflicting theories about the tiny breathe hole on the intake
manifold breather, this is on the Vanagon diesel engine. >>

<>


Does the  normally aspirated engine have an exhaust gas recirculation (EGR)
system? My TDI has and also has a small port at the location in the intake
manifold where the EGR valve is located. The port on the TDI is a necessary
feature to prevent the higher than atmospheric intake pressure from
eventually leaking past the seal around the actuating rod and blowing out the
operating diaphragm. The valve is opened by the rod. The rod is actuated by
pressure difference. The difference in pressures could be from a vacuum pump
source, as the fine Teutonic teetotalers designed, or from the boost pressure
on the other side. The valve doesn't care whether the pressure difference is
vacuum over atmospheric or if it is atmospheric over boost. The vent hole
bleeds off whatever boost pressure makes it past the rod seal before it can
affect the normal EGR operation.
The port on a N/A diesel could be a vestigial remain of a common turbo /
normally aspirated manifold.
Merely a guess, I'm neither German, nor an engineer.
Nor a teetotaler.
Jonathan Bartlett