My AAR was dead. Not only that but it shorted out and ruinined my ignition harness. The hot lead coming from underneath the unit lost its insulation. The valve and the heating element were both inoperable. Here's how I fixed it.
The AAR is a can holding a spring. The spring is really a bi-metal strip curled to resemble a watch spring. It serves as a thermostat. A valve on top of the can is regulated by that spring. The valve admits "auxillary air" to the manifold.
I opened the can by first cutting slots across the top of the "lip." I used a pneumatic cut-off saw. You could use anything that cuts metal. As you can see I was not very careful and it turned out alright.
Opening the can separates it from the valve and exposes the spring. Tow screws are attached to the spring. The one on the side is the adjustment. It is self-explanatory given that it controls where the opening of the valve is in relation to the spring.
The other screw retains the spring to the valve shaft. It provides a handy place to put a small screw driver so you can turn the valve back and forth. I loaded the valve with penetrating oil. I had to remove the spring to really work it until the valve turned smoothly. The spring comes on and off easily. There is a tiny cotter pin holding the shaft in place, but you don't have to remove it.
Excuse the duplicate photo. Next...
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Next I addressed the heating element in a ceramic fixture riveted to the bottom of the can. Drill the rivet out, as wall as the two terminal rivets for the heating element. Take it all out.
I put a couple of holes in the side of the can to run a positive and negative lead. I didn't want any wires underneath the can to get pinched when you screw it to the engine.
I had some resistors in a shoebox in my garage. I eyeballed a couple and soldered them together. Long lead is positive. If you want to precisely duplicate the heating element -- good luck. Dave Darling recommends 120 ohms. I can't argue with him.
The resistors in the bottom of the ceramic cup are a tight fit. I grounded them through the bottom hole and applied a dollop of solder to the negative lead from the outside. The positive wire is routed out through one of the holes in the side.
No problem, but it took to long to adjust the resistors so they wouldn't interfere with the spring when I put everything back together. I decided to try another way....
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I soldered another beefier resistor to insulated wires and ran these out the holes I'd drilled in the side of the can. I tested the assembly to make sure it put out heat. It did. Then a smeared a dab of RTV all over the positive terminal
This fixed the resistor and insulated the hot side.
An extra benefit to cutting slots in the lip of the can is they make it easy to realign the top with the bottom. A big pair of channel locks squeezes the lip back onto the cover. It's not a tight fit so two "tacks" of solder hold it.
Note the acid core solder, it is essential for joining steel.
That's it. it works fine. Open when cold, closed when warm. The resistor gets it warm enough to close tight in about 10 minutes. I've not tested the operating time attached to an engine at start up.
Great write up ! Do the resisters determine how long it takes for the AAR to close ?
Unintentional duplication of post. Don't know how, but sorry.
Hey, cool! I don't remember the adjustment screw from when I had mine apart--but other than that, yours looks exactly the way I remember.
I actually used a flat-head screwdriver as a chisel, and hammered it into the lip that folds over the top of the can. Fold it back, and the lid comes off just like you show here. I took my inspiration from the odometer repair process; un-crimp the outer thing to remove the inner part.
I don't know how critical the resistance is. If yours closes in 10 minutes, it's probably good enough. The ones that I have measured (three different 2.0 ones) were all right around 13 ohms; when you have ~14 volts on your system and then a 13 ohm resistor to ground, you will dissipate just about 1 watt of power, which is why you want at least 1A rated resistors for that.
With 120 ohms, you'll dissipate less power and not need resistors rated as high. (Probably on the order of 100 mA, or 0.1 Amps?)
--DD
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