[T3] Two Tests
willjahn975 at gmail.com
Sun Sep 22 16:14:36 PDT 2019
After I cleaned the PCV I checked with a hose and tried to blow through
both ends and could not so it seems to be seating well , didn't want so
draw in the cleaner so i just tired to blow through it. I'm sure the vacuum
is much stronger. I tried running it with the hose plugged to the IAD yet
nothing changed with the idle with TS1 connected.
I'm still confused on the PCV operation. In the link I posted when at idle
the vacuum is highest so the disc in the valve is seated on the intake side
/vacuum side so the disc is seated and the three metering slots permit a
regulated flow of gasses through the valve. There is no way the see the
metering slots . I see the disc it pulled down all the way at idle should I
assume the vacuum I feel if I place my finger over the valve installed with
just the breathers plastic cap off is through the metering slots? This
valve is the same part number T-3's used. After I cleaned it the vacuum I
felt was not quite as strong yet still existed.
On Sun, Sep 22, 2019 at 3:37 PM Jim Adney <jadney at vwtype3.org> wrote:
> On 20 Sep 2019 at 14:33, William Jahn wrote:
> > Today I looked at the PCV . it's pretty gunked up. On this site
> > https://members.rennlist.com/pbanders/PCV.htm
> > It explains the PCV operation and from what I read it seems most of the
> > time it stays close to closed .
> Our '72-3 PCV system hardly needs any explanation. It's terrribly simple.
> Filtered air gets sucked from the air cleaner into the heads and down the
> pushrod tubes.
> From there, it mixes with any blowby in the crankcase and then gets sucked
> out thru the breather box and into the IAD. Variations in the amount of
> admitted would alter the idle speed.
> The PCV valve opens under manifold vacuum, so it will be most open at
> when the manifold vacuum is at its max.
> One thing you could do would be to plug the pipe that leads to the front
> the IAD. If that stops your odd symptoms, it means that there's something
> irregular going on in your crankcase ventilation system. If something is
> gunked up, it could be preventing the free flow of air, and only letting
> air thru
> in "burps" which might make the idle uneven.
> I've never seen this happen, but it sounds possible, and it's easy to
> I'm not recommending plugging that pipe as a solution; that would be bad
> and will lead to different problems. But it's worthwhile as a short test,
> just to
> see if the PCV system is part of the problem or not.
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
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