Date: Thu, 22 Jul 1999 07:34:33 -0400
Reply-To: Bulley <gmbulley@BULLEY-HEWLETT.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Bulley <gmbulley@BULLEY-HEWLETT.COM>
Subject: Hot EGR?
Tom-
Now you are getting a little deeper in to the one sentence in my story:
"Repairing the ERG system to "like new" condition was difficult"... Yep,
our wire melted, not chaffed. And yep, our pipe gets hot.
What you say is true...The EGR isn't normally piping hot. Ours doen't when
driving around town. Under *certain* conditions however, (like 3/4 throttle
climbing a grade for 2-3 contiguous minutes going 65-70 mph), the pipe can
get very hot. If yours doesn't, you may want to change the filter, clean
out the EGR valve, pipe, and the distribution pipes inside the intake
manifold. The distribution pipes are the key, as they are often completely
blocked with carbon, and don't flow. I've found this on three of my last
three type 4's.
You may want to check the chemistry on the temperature drop on the
exhaust-in-combustion thing. I had three different folks tell me the same
thing over the years, including one veteran VW guy, and one emissions tech.
I don't know the chemistry, but believe what I was told. One of them cited
a drop of 150-200 degrees in combustion temp, but I have no way of
knowing...I'd love to know for a fact, but it makes sense to me. Combustion
taking place with smoke mixed in can't burn as fast, I would think. Anyone?
Gilligan, go get the Professor.
True, the ERG wasn't originally designed on the type 4, but a lot of
"cooling" things weren't (like the flapper valve re-direct exhaust pipes,
and the #3 cylinder warm air exit at the front of the tin...). When VW
found the EGR cured some temperature ills you will note that they changed
the distribution pipes inside the intake. On my 1976's, they were balanced,
one or two holes on the EGR intake feeder pipes for each cylinder.
On our 1982, the #3 cylinder EGR feed pipe has four 2.5mm holes, the # 1
has two 2.5mm holes, #4 cylinder has one small hole, and #2 has none. It
took 3 days of soaking ours in carbolic acid and some serious hours of
reaming with light wire to clear ours...you might be surprised at how much
carbon is in yours. Perhaps that is why yours doesn't get hot?
As far as the metering gasket: it is obsolete, and no longer available
through VW. We re-used ours after a thorough cleaning. The original hole in
ours was about 3-4 mm, rather than 1mm. Maybe yours is clogged? Maybe ours
is worn? Either way, ours runs great, and I actually look forward to
getting the emissions checked in another 500 miles...
Look forward to your thoughts,
G. Matthew Bulley
Bulley-Hewlett & Associates
www.bulley-hewlett.com
Cary, NC USA
888.468.4880 tollfree
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