[T3] 73 auto trans type 3 ARR ?

[Keith Park]

Get some choke cleaner, or propane, and look around for a vacuum leak...

Keith


Topnotch Restorations
topnotch at nycap.rr.com
http://www.topnotchresto.com
71 Squareback  “Hothe”
65 Notchback  “El Baja Rojo”
93 RX7  “Redstur”
13 Subaru Outback "Blendin"

-----Original Message-----
From: type3-vwtype3.org <type3-vwtype3.org-bounces at lists.vwtype3.org> On Behalf Of William Jahn
Sent: Saturday, June 10, 2023 4:51 PM
To: type3 at vwtype3.org
Subject: Re: [T3] 73 auto trans type 3 ARR ?

 I checked the AAR today and drove the car. The AAR was open cold 76 Degrees here. After I blew in the hose to see if it was open, engine off.
Then I drove it today the RPM never increased and actually dropped down to
800 RPM in drive. Once I got home I checked it and it was closed. I didn't feel any suction at all however the idle was back up to 1400 RPM.

 I now know it's not the AAR , Since it does at times drop to 800 RPM in drive at least today it did, Then with the AAR closed and I did not adjust the Idle speed because when this rpm rises I have 1000 RPM in drive. All I can think of is some new vacuum leak and I didn't see any hoses off and just changed them all last year along with everything else intake gaskets, Rummer boots , injector seals, fuel lines, every single hose.

 All I can think of is a new vacuum leak or the dist sticking maybe a broken spring  but it does not ping one bit. It does run fine.  I hoped it would be simple , guess not.

William

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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