Date: Sun, 9 May 2010 12:07:10 -0700
Reply-To: Alistair Bell <albell@SHAW.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Alistair Bell <albell@SHAW.CA>
Subject: throttle body fun
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i posted this text plus pics on my blog (http://shufti.wordpress.com/)
Yesterday I decided to take the throttle body off my ’86 syncro (2.1
l), to clean it up and double check the throttle valve position
switch. Well it turned into one of those “why did I do that?”
projects.
I had more than just idle curiosity driving me, the van had been
having occasional lag in standing start acceleration which I thought
might be due to the throttle valve position switch (TVPS), even
though it had been recently adjusted. I was suspicious that the
throttle shaft fit in the throttle body was loose and that might be
affecting the TVPS.
Getting the throttle body off is pretty easy, I did find that the two
bolts holding it onto the plenum were not tight, I wondered if that
had allowed a little air leak? Who knows.
Got the throttle onto the bench and gave it a quick cleaning. Wasn’t
as oil crusted as I had expected, someone must have been in here in
the last few years. The TVPS had a black plastic cover on it, I had
not seen that before. It sure keeps the actual switch nice and clean,
see photos.
The bore and butterfly had wear in them, as expected. The design of
the TB allows axial play and this lets the butterfly rub on the bore.
The pics don’t show it quite as well as I had hoped. But there
didn’t seem to much if any lateral play that would affect the TVPS
setting.
Using a multimeter set on ohms and “beep” for continuity I check
the TVPS setting. it was within spec, but I managed to fine adjust it
to fall between a 0.003″ feeler gauge and 0.002″ shim stock. I was
feeling pretty cocky at that point, and toddled back out the the van
to re-install.
It was then I noticed the little clamp that connects the throttle
cable to the TB was missing, argh. I must have dropped it between the
van and the bench… probably on the gravel driveway. I spent quite a
while searching, with magnet too, but no luck.
So I ended up making a quick and dirty substitute. Mild steel and a
5mm hex socket machine screw. It worked out ok.
I figured I’d blow the entire afternoon and take the crankcase
breather tower off and check the O-ring that seals it to the case.
The O-ring was as hard as hard can be, was it ever soft? It was also
broken. The old ring broke into pieces getting it out. I didn’t have
a replacement in the collection but I had a spare breather tower and
I swiped the O-ring from that.
Cleaned up the oily mess from all the associated hoses, placed some
sections of braided rubber vacuum lines, and put everything back
together.
The van runs pretty well the same, maybe a tad higher idle, will deal
with that later. Needs a few more miles of driving before I admit it
was all a waste of time.
alistair