[T3] thermostat issue

[Jim Adney]

On 14 Oct 2011 at 11:29, Bryon Garvin wrote:

> I am not sure how long this has been going on, but I suspect not very long.
>  My flaps don't seem to be moving.  This was all properly adjusted some time
> ago with a new thermostat and I have all of the linkage, fortunately.
> 
> I made a mark on the shaft so I could tell if it was turning or not.  Not a
> cut on the end like some of you do because I haven't had the engine out
> before.  But anyway, this mark showed that the rod was turning.

I like to make the mark in parallel with the flap, so I can see at a 
glance which way the flap is pointed. There's also an advantage to 
making a slot, because then you can use a screwdriver to try to turn 
it. If it won't turn, then you know the shaft has seized; if it turns 
freely, you know the adjusting screw has come loose.

> My Fastback will sometimes idle-hunt for about 1 minute as I leave the
> neighborhood on a cool morning.  Runs fine when you press the accelerator,
> but at a stop sign it will surge up and down.  Car runs great when warm.
>  But today, the hunting continued for much longer than it usually does.  It
> eventually stopped but I was thinking about this problem while driving and I
> wondered if the thermostat was working.  I got to work which is only 3-4
> miles away and looked at the mark.  I can't remember if the position of the
> mark meant "open" or "closed" but came back an hour later to inspect and the
> thermostat was retracted, yet the mark didn't move.  So, I am looking at the
> flaps being either open or closed and I can't remember like I said, what the
> mark meant (stupid move, I know).

The odd idle behavior probably has nothing to do with the thermostat, 
but it might.

> Is the most likely scenario here that the adjustment nut that holds the
> throttle flap rod has loosened ?  I will have to look into this this
> weekend.  I think I have the adjustment procedure saved somewhere so I will
> review that.  I hope the spring isn't broken.  I assume anything beyond this
> nut coming loose would require dropping the engine to remove tin and see
> what is going on?  I adjusted it all before by blinding working in the
> access hole when you remove the "goggle" piece.

My first suspect would be the fixing screw that you reached thru near 
the #2 SP. I've never seen one of those spring break, but it's 
important for it to be there, because it forces the flaps open if the 
fixing screw comes loose. Open is a much better default than closed.

There's a plastic clip for the SP wires on the sheet tin just in 
front of the fan housing, under the rear end of the air filter. 
(front is front, rear is rear.) I think you can remove that clip and 
peek thru the hole and see the flap if it is open. If it's closed, 
you probably can't see it, but you might be able to feel it with a 
length of wire.

Once you get this fixed again, it's not too hard to saw a small kerf 
in the end of the shaft while the engine is cold and the flap is 
close to vertical.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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