Rebuilding the Aux Air Valve - D-Jet

vwduud · Post by **vwduud** » Sat Mar 15, 2003 9:35 am

Has anyone done it. Dave Darling, Brad Anders recommended I get your input. It seems as though the heating coil in mine is inoperable. The only time it heats up enough to reduce the idle, is typically after letting the engine sit, after running for awhile. Heat soak allows it to warm up. I will be taking a resistance reading today, but wanted to get anyone's input on replacing/repairing the heating element (if necessary). Brad recommended 13 ohms worth of wire wound resistors. Is there more to it than that? Also, advice on the surgery required to carefully disassemble/reassemble it. Thanks - Jim

raygreenwood · Post by **raygreenwood** » Sat Mar 15, 2003 2:26 pm

Actually,yes... you can use almost anything for wire...but the bigger the wire...the smaller the area the heat is in...because it takes less fat wire to make the same resistance. Thin wire alows you to spread it around. The resistors sound like a cool idea. 13 ohms is stock..but a little higher is no problem as long as the wire and the fuse are upgraded. The screw is in a slot at the top of the bimetallic coil spring. The spring then comes out of the slot in the valve shaft. The valve shaft then has a pin mounted in it. You have to turn it to get it to push up through the "keyhole" opening...and of course...you need to pop the outer elbow out of its crimping. It goes right back in. Then peen it once so it stays. You will notice that the slot in the tube valve has a small end to allow some by-pass. The good thing about adjusting this thing to suit the engine, is that if you have done fuel mixture adjustments to the MPS...but have basically run out of idle screw...by adjusting the AAR valve to leave you a little more or less opening, you can use it to help augment the idle screw position when it is fully closed and warmed up.
Yes, the AAR can be a minor vacume leack source...so its good to seal it well. Ray

94teener · Post by **94teener** » Sat Mar 15, 2003 5:33 pm

JCWhitney sells new aux air valves for the VW. 71-73, $59.95 and for the 74, $44.95.

They look just like the ones in the 914.

Phil

94teener · Post by **94teener** » Sat Mar 15, 2003 5:40 pm

Here is a pic of the JCW AAR.
http://images.prosperpoint.com/1070/54506-89.jpg

Phil

raygreenwood · Post by **raygreenwood** » Sat Mar 15, 2003 9:22 pm

Yes that will work fine..but its not the same part. That casting..with many changes...is used on everything from buses, to rabbits, volvos. In order for it to fit correctly and not be obtrusive, the flange that the original pot shaped AAR sits on and bolts to the plenum...will have to be cut off. There is a small sheet metal factory piece that bolts to the case bolt and then to the AAR. Then a new elbow. But the elbowthat fits that unit wdoes not alow the hose for the Decel valve (if you have one). Ray

vwduud · Post by **vwduud** » Sat Mar 15, 2003 9:24 pm

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by 94teener:
<B>JCWhitney sells new aux air valves for the VW. 71-73, $59.95 and for the 74, $44.95.

They look just like the ones in the 914.

Phil</B><HR></BLOCKQUOTE>

Has anyone ever used one of these? Not sure if the photo is just a generic photo of one of the many listed in the JCW catatlog, but it does not represent the type IV verison found on the D-Jet, in the 914. For the price, however, it wouldn't be too big of a gamble to try one. What do you think? Ray? Dave? Thanks for the tip 94Teener.

raygreenwood · Post by **raygreenwood** » Sat Mar 15, 2003 11:12 pm

Lots of ways. One I have done is to cut 3-4 notches in the rolled lip that holds the top to the bottom. Cut them clean, evenly spaced. This will all you room to both carefully pry the 4 segments of rolled metal back...and/or pry the plate and vave out of the top. Mount the body in a vice...but first...cut a hole just slightly larger in diameter than the body of the AAR...with a hole saw...in a block of wood. Cut that block down the middle. Now you have a set of custom made "soft jaws" to hold the can in the vice. You are trying not to bend it up. Make sure you marke the body of the valve to the can so it goes back in the right position. What you will see in the bottom of the "can" is a ceramic cup with what appears to be a ni-chrome coil going around it. Usually the coil is burned out. You can either locate .003-.005 diameter ni-chrome wire...and rewind a coil just like you see, (remembering to measure the resistance over the length of the wire)...or you can modify a choke element from a 34 pict 3...to drop in. Both are equally difficult. The white cedramic glue that holds the wire down is available at almost any large electronics shop. Its heat sink cement. The ceramic cup is held in by a rivet. One end of the coil is attached to that and hence grounded to the frame. The positive comes in from the bottom as well.
While you are at it...locate the set screw that adjusts how far the spring opens or closes the valve. You will see a + or- mark there as well. Make a note of the position, remove the screw...clean and polish the valve. Before you reassemble...mark the location on the can...where the screw will be inside. Drill a clean hole into the can so you can now access the screw to addjust the opening and closing distance of this valve to suit the engine. You will need to find a clean plug for this hole or make one.

That funky block of wood you cut the hole in will now be used as a tool...to help crimp this thing back together. Line everything up...put the can into the hole....load it into the vice and squeeze...turn it a few times. Then take it out...sand a little from one side of the wooden block tool...and re-situate the thing in the vice so the flange of the can is now resting above the whole in the bolocks. Fing a piece of pipe of the right size. Use your dremel to cut a notch in it so the upper vacume hose fitting proctrudes...and use the pipe ...and a hammer to peen the top down tight. If you did not cut your nicks too far down at the beginning..this should seal up well. Ray

Dave_Darling · Post by **Dave_Darling** » Sat Mar 15, 2003 11:26 pm

I just used a hammer and chisel on the rolled-over lip--it's pretty thick, but will eventually un-bend.

I don't think you have to bother with the Ni-Cr wire; just about anything that gives you 13 ohms of resistance and will stand up to 1 watt of power (for a long long time!) should generate enough heat and work pretty well. I think there's room for 13 ohms worth of ceramic "bathtub" resistors, they usually can take a lot of power.

Ray, I never saw the screw. Hmm, maybe I'll dig back into mine...

I reassembled by using the hammer and chisel to push the lip back over the lid again in a few places. Then a bead of RTV around the gap, and that was all. I don't think the can itself winds up under vacuum, but I wasn't certain so I sealed it.

--DD

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1974 VW-Porsche 914 2.0 (Type IV powered!)

Pelican Parts' 914 Tech Geek http://www.pelicanparts.com

raygreenwood · Post by **raygreenwood** » Sun Mar 16, 2003 9:19 am

Until I got rid of the AAR last year, it was what I have been sing. I have several stock type 4 (round one s) that I have not had time to rebuild. This model (many call it the"whitches hat" version) was used on some of the later model buses. It works as well as the original round D-jet model...and isactually a much more dependable design. But...unless you just want to mount it out of the way...and hose it into the plenum, ...which is fine...but looks odd, then you need that little piece of sheet metal to mount it with. The good thing about just using hose...and say mounting this thing out of sight, is that you can connect the original screwy little rubber T-nipple that feeds the decel valve , onto the plenum where it belongs, with a metal nipple going to the hose that connects to the remote AAR. If you need an AAR...and don't have a stock one ready...get one of these. BUT....go look at one of the correct part # before you get one at whitneys. There are several differnt types of connectors. There is single pigtail connector, there issingle T-1 connector, there isdouble wire (hot and ground) using L-jet plug, there is double wire using D-jet plug. There are easily 30+ models with differnt hook-ups and or calibrations and hose sizes. All have some level of adjustability as well. Many have totally different plate sizes and orifices inside. Some are designed to not close all the way. They have a byppass hole (a lot of volvos are this way). The time variation for closing is huge. I reccommend going to really ugly junkyards...and collecting a handful of different models to try out. Ray

Dave_Darling · Post by **Dave_Darling** » Sun Mar 16, 2003 10:56 am

The one shown is very similar to the valve used on most or all of the 1.8L 914s.

Note that the older cannister-style AAR has a single electrical connection, while the type shown looks like it has two. The original grounds through its case, while the JCW one ground through the second pin in the connector.

--DD

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1974 VW-Porsche 914 2.0 (Type IV powered!)

Pelican Parts' 914 Tech Geek http://www.pelicanparts.com