[T3] 73 auto trans type 3 ARR ?

[William Jahn]

I checked the electric one in my car a bit ago. It's cold, well 70 degrees
F. I was able to take it apart 2 years ago . The reason mine was stuck
open, I didn't find oil in the rotating valve bore. What I found was rust
in the bore and a small amount on the valve. The entire top in steel the
valve is plated like chrome.

What was concerning was the small end of the valve shaft that goes down to
the bi metal spring and passes through a bore was also worn , it was the
only area that was worn. I polished it as much as I could. It did work for
a few years. Now I fear that might be where it binds.

 As far as the case, I do  know the case that I removed had an X prefix and
it has the large bore. The one I rebuilt and used is a  U prefix and was
also used in 73 . I can't recall if it has the large bore since it was 1997
when I rebuilt it , I didn't notice any difference or anything that stood
out or being different . Both cases  were for auto trans cars. I really
don't know if the case I removed was the factory case.

 The mechanical valve I have is Bosch part number 0 280 140 001 vw #
311133040. The top screws don't look like they were over tightened. I hope
the case studs are all the same size. They seem to be and the electric has
this base with rather large nuts , didn't check appear to be 15mm.

 In order to do this I need to remove the electric AAR and then clean the
base so no crap falls into the oil and hope the bore is the large size.

On Fri, Jun 9, 2023 at 12:15 PM Jim Adney <jadney at vwtype3.org> wrote:

> A few more comments on our AARs.
>
> There were two different versions: a mechanical one for '68-9 Type 3s as
> well as all later MT Type 3s, and an electrically heated one for '70-3 AT
> Type 3s. To the best of my knowledge, VW/Bosch introduced the electrically
> heated one to heat up faster to meet emission specs for AT cars.
>
> The mechanical AAR has a bimetal spring, just like the one you used to
> have
> in your home thermostat. That bimetal spring sticks down into the engine
> case and gets splashed with engine oil, so it heats up with the engine.
> The
> bimetal springs do not wear out, but the housing is a zinc diecasting,
> which
> can distort with time, causing the shaft to stick. This is particularly
> likely if
> someone overtightens the two screws on the top. This pulls on the zinc in
> a
> way that will distort the housing and cause the AAR to stick in place.
>
> I can lap the housing bore and reset the spring to open and close
> properly.
> It's not a hard job, but I had to make some special fixtures to do it
> easily and
> correctly. I Locktite the screws, so they don't have to be tight.
>
> The electrical AAR is a crimped assembly, so it can't be taken apart
> without
> cutting and bending things. It pretty much amounts to something you CAN
> take apart, but it's not likely to go back together nicely afterwards.
> I've never
> done it. They also stick, but I'm not sure why. Sometimes they can be
> freed
> up by cleaning with some sort of solvent, but often this doesn't work. The
> only way to fix them is to replace with a working one.
>
> Replacing an electrical AAR with a mechanical one should be fine. It might
> not heat up as fast, but this is unlikely to be noticable unless you're
> driving in
> extremely cold weather (think freezing or less.) Being able to fix the
> mechanical ones is a huge advantage.
>
> There's one possible problem with this replacement: I've been told that
> some
> late AT cases do not have that hole drilled out, to let the MT bimetal
> spring
> AAR stick down into the case. I've never seen this, but I've heard others
> make this claim. If anyone comes across an AT case that does not have that
> drilling (the one for a carb type fuel pump pushrod) please take a picture
> and
> let me know.
>
> Testing:
>
> The ONLY reliable way to test whether your AAR is open or closed is to
> block off its air inlet with your thumb, with the engine running at idle.
> If the
> idle speed drops, the AAR is at least partly open. If the idle doesn't
> change,
> the AAR is closed.
>
> It's important to understand that closed does not mean a complete shutoff
> of
> air. It's not a fully sealing valve. Some air will always pass thru, but
> if the
> valve is in its closed position, there will be too little air to alter the
> idle speed.
>
> --
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
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