<div dir="ltr"><div>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. <br></div><div><br></div><div>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. <br></div><div><br></div><div> 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.<br></div><div><br></div><div> 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. <br></div><div><br></div><div> 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. <br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Jun 9, 2023 at 12:15 PM Jim Adney <<a href="mailto:jadney@vwtype3.org">jadney@vwtype3.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">A few more comments on our AARs.<br>
<br>
There were two different versions: a mechanical one for '68-9 Type 3s as <br>
well as all later MT Type 3s, and an electrically heated one for '70-3 AT <br>
Type 3s. To the best of my knowledge, VW/Bosch introduced the electrically <br>
heated one to heat up faster to meet emission specs for AT cars.<br>
<br>
The mechanical AAR has a bimetal spring, just like the one you used to have <br>
in your home thermostat. That bimetal spring sticks down into the engine <br>
case and gets splashed with engine oil, so it heats up with the engine. The <br>
bimetal springs do not wear out, but the housing is a zinc diecasting, which <br>
can distort with time, causing the shaft to stick. This is particularly likely if <br>
someone overtightens the two screws on the top. This pulls on the zinc in a <br>
way that will distort the housing and cause the AAR to stick in place.<br>
<br>
I can lap the housing bore and reset the spring to open and close properly. <br>
It's not a hard job, but I had to make some special fixtures to do it easily and <br>
correctly. I Locktite the screws, so they don't have to be tight.<br>
<br>
The electrical AAR is a crimped assembly, so it can't be taken apart without <br>
cutting and bending things. It pretty much amounts to something you CAN <br>
take apart, but it's not likely to go back together nicely afterwards. I've never <br>
done it. They also stick, but I'm not sure why. Sometimes they can be freed <br>
up by cleaning with some sort of solvent, but often this doesn't work. The <br>
only way to fix them is to replace with a working one.<br>
<br>
Replacing an electrical AAR with a mechanical one should be fine. It might <br>
not heat up as fast, but this is unlikely to be noticable unless you're driving in <br>
extremely cold weather (think freezing or less.) Being able to fix the <br>
mechanical ones is a huge advantage.<br>
<br>
There's one possible problem with this replacement: I've been told that some <br>
late AT cases do not have that hole drilled out, to let the MT bimetal spring <br>
AAR stick down into the case. I've never seen this, but I've heard others <br>
make this claim. If anyone comes across an AT case that does not have that <br>
drilling (the one for a carb type fuel pump pushrod) please take a picture and <br>
let me know.<br>
<br>
Testing:<br>
<br>
The ONLY reliable way to test whether your AAR is open or closed is to <br>
block off its air inlet with your thumb, with the engine running at idle. If the <br>
idle speed drops, the AAR is at least partly open. If the idle doesn't change, <br>
the AAR is closed.<br>
<br>
It's important to understand that closed does not mean a complete shutoff of <br>
air. It's not a fully sealing valve. Some air will always pass thru, but if the <br>
valve is in its closed position, there will be too little air to alter the idle speed.<br>
<br>
-- <br>
*******************************<br>
Jim Adney, <a href="mailto:jadney@vwtype3.org" target="_blank">jadney@vwtype3.org</a><br>
Madison, Wisconsin, USA<br>
*******************************<br>
<br>
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