Auxillary Air Regulator....torn apart and repaired

[wizard124]

A brief description: The AAR, on the FI spiders, allows additional air for cold start purposes. Once the car starts, voltage is supplied to the AAR which heats a bimetallic strip. As this strip bends, a spring pulls a plate across the orifice gradually closing it off.
The resistance of the coil around the bimetallic strip is approximately 58-59 Ohm. This was determined by measuring the 4 AARs in my collection.

What we are talking about:


Took a dremel blade to the crimped edge and back 4 tabs to open:




This was the condition of the plate:


Some epoxy to the 3 pieces. Then, I used some aluminum tape to further strengthen the plate. I bent over addition tape to the 3 broken areas.


My heating strip was loose in the housing. I drilled out the retaining pin:

The plate carrier is attached to the housing with a single nut. There is some adjustment available allowing for more air or more closure. This a picture of the innards re-assembled. Note the small opening:


This picture shows the AAR hooked up. After starting, with voltage going to the AAR, the coil/bimetallic strip heats. The strip slowly begins to bend away from the tab of the plate, allows the spring to pull the plate and closes off the air orifice. You can see the plate has moved to its limit and now hits the tab on the housing.:


I'll tab the cover closed using some epoxy then seal it with silicone. It should be good to go as a spare.

[RRoller123]

One of the best threads in many a time. Thanks!

Pete

[narfire]

Man.. are you psycic or what. I just ordered a working used one but with your pics and tutoring, I could have had a go at my current AAR. Might still have a go as I have another somewhere in the shop....
(car is a bear to start in the cooler morning temps)
Thanks for the pics...well done
Chris

[Ramzi]

How much do you charge?

Great thread!

[wizard124]

Pete, Chris, Ramzi,

I'm flattered by your praises!
Knowing those are problematic, I decided to sacrifice it to find out how it works. Not sure how many cyclesit would be good for? Maybe smear more epoxy on the visible side to further strengthen the plate?

A pretty simple contraption, why all the problems?

Warren

[focodave]

Looks like it may be easy for one to make their own plate out of some other stronger material, using the original as a template/pattern.

[stpher]

Hi,

We used to run into this problem on early BMW 320i's same AAR If you can see a liitle of the opening, take a very fine small round file and insert it through the opening and very carefully grind out a little bit more of the opening on the disc, the disc is made of a fibre material so it can be filed. Do this with the AAR cold so the inner disc has some tension on it so you can file away. It does not take much and you can keep going and get whatever cold idle rpm you want, just make sure that when it does warm up, the disc closes over the opening completely. Worked about 90% of the time, the other 10 would have to be replaced.

Good luck with that

Thanks, Rick

[RRoller123]

Quick question, when fully warmed up, does a properly working AAR COMPLETELY close off the opening? Or is there a small opening still left?

[Kevin1]

When closed the AAR will block all, or very nearly all, of the air. You can test this by clamping off the air hose after the engine is fully warmed up. Ideally the idle speed will stay steady with no air coming through the aux air regulator. Idle speed at that point should be governed by a combination of the idle bypass on the AFM, the idle speed adjustment screw on the intake manifold, and the position of the throttle plate.

[RoyBatty]

Yes wiz,
But is this related to your previous thread about not being able to rev the engine beyond 2500 RPM?
Is that issue resolved?