[T3] On a 73 T-3 SB fuel injected auto trans pinging
Bobsnotch at aol.com
Bobsnotch at aol.com
Sat Dec 9 17:58:18 PST 2017
In a message dated 12/9/2017 8:30:58 P.M. Eastern Standard Time,
phil.hof at ostronic.org writes:
Lastly, I’ve said this before, but the late model breather/PVC is
different than the early style, and I hear that faults can cause vacuum leaks that
might cause at least some of your symptoms. If anyone has a good diagram
and discussion of how the late PVC system works, we could set this right and
eliminate another variable.
This is the 1 thing that Ray really doesn't like about the 2 cap PCV system
VW used. It has a bad tendency to open when it wants, and causes a miss.
What most of the type 4 guys do, is to strip out the guts of the valve, and
add a slug with a drilled hole in it (can't remember what size right off
hand) in the vac hose to the plenum. What this does is allow you to tune
around the "constant vacuum leak" of the small hole. I only mention this, as
all of the type 4 engines (bus, T-4, 914) use that same valve set up, and
have issues with it. I haven't really studied how the VW designed PCV system
really works, but then I've only got 1 t-4 engine here, and it's on carbs.
The rest of the type 3 engines are all 1 cap breather models, so no real PCV
set up.
I hope this helps.
Bob 65 Notch w/Factory Sunroof converted to IRS
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