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Awhile back someone got rid of their electric VSVs and installed a 5-way air valve. Got rid of VSV is the thread if you'd like to read it. There wasn't really any information provided by the rdfenn3 though. So I thought I do some research and then convert my Trooper. Turns out it's very easy to do.

Items needed:
1--5-way pneumatic valve
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1--90 degree barbed elbow
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2--straight barbed elbow
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2--pneumatic filter
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31'--vacuum hose

The 5 way valve comes in a few configurations but they all operate the same way. You flip a lever or push a button causing the valve to open different air ways inside. I believe rdfenn3 used an Airtec valve but I found a great deal on a Norgren. Regardless of which company you go through the valve will have a 2 position switch/button with 3 air ports on one side and 2 air ports on the other.

On the 3 port side of the valve install the 2 pneumatic filters in the outer holes and the 90 degree barbed fitting in the center hole. You'll have to orient the 90 degree fitting to work with where you decide to install the valve. The 2 port side of the valve gets the 2 straight barbed fittings.
IMG_20140508_120836_816.jpg
 

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Next step is to decide where you want to place the valve. I really wanted to place the valve on the dash in one of the unused button spaces to the left of the steering wheel. The problem is there's zero room to route the vacuum lines. I ended up mounting the valve to the lower dash panel next to the steering wheel. I didn't have the correct size drill bit so I drilled the hole as large as I could then used my Dremel with a sanding bit to enlarge the hole to fit snugly. Sorry this picture is bad but it was dark and I was a bit drunk.
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After the valve location you need to decide how to get your vacuum lines through the fire wall. Conveniently for me my truck is an automatic so I used the clutch hole cover. It's held on by 2 nuts. Started out by drilling 3 holes through the cover. Make sure to select a bit slightly larger then your vacuum line out diameter.
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Once those holes were drilled I used my Dremel with a grinding bit to make a nice slotted hole.
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Then because I'm super anal and didn't any sharp edges I used my file set to make the edges perfectly smooth. This step isn't required
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After that was done I wrapped it in electrical tape and installed. No picture of it installed.
IMG_20140322_195506_232.jpg
 

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Now that I had a hole through the firewall for my vacuum lines I disconnected the vacuum feed going to the VSVs. No picture but if you have the 96-97 SOHC engine it's the line coming off the passenger side of the intake manifold all by itself. There's a 1-way check valve installed on this line and it has to be installed in your new vacuum line. Make sure the arrow on the valve points towards the manifold
IMG_20140322_185406_491.jpg

I replaced all the vacuum line running to the VSVs so I routed the new line along the fire wall and used connectors to anchor it to the brake lines. I can get a picture of it if anyone needs it.
One at a time I pushed the new vacuum lines through the fire wall and up to valve. Make sure to give yourself some 4-6" slack with each line and don't forget to label them. Mine are labeled "Supply, 4wd and 2wd."
IMG_20140323_140649_771.jpg


This part is tough to explain but hopefully everyone understands. Please reference the picture below. In the picture the lever is in position A or lever up.
Port 1 is vacuum supply
Port 2 is 4wd
Port 3 is pneumatic filter
Port 4 is 2wd
Port 5 is pneumatic filter
When the valve is in position A(lever up) Port 1 and 4 are connect causing the axle actuator to disconnect the axle shafts. Port 2 and 3 are connected allowing air to flow into the 4wd side of the axle actuator. If this doesn't happen the actuator WILL NOT move.
When the valve is in position B(lever down) Port 1 and 2 are connected causing the axle actuator to connect the axle shafts. Port 4 and 5 are connected allowing air to flow into the 2wd side of the axle actuator. if this doesn't happen the actuator WILL NOT move.
IMG_20140508_120816_256.jpg


Once that part is done make sure the 2wd hose goes to the passenger side of the axle actuator and the 4wd hose goes to the drivers side. They aren't pictured but I had to use hose clamps to keep the vacuum hose from slipping off the axle actuator nipples. For whatever reason the axle actuator nipples are too small for 5/32" vacuum hose but that size worked perfectly everywhere else. I found the hard way during a water crossing.
IMG_20140322_215215_462.jpg

When routing the hoses I when underneath the Fuel Vapor Canister & Air box then down past the steering box to the axle actuator. I tried to get a picture of it but since the hoses are underneath everything you can't really see anything.

Once all the vacuum lines are routed and secured I put the lower dash panel back on. The valve would only fit in a horizontal position so my switch moves left/right instead of up/down. But it's tucked up out of the way and I've yet to unintentionally hit it.
IMG_20140508_131203_209.jpg


I'm sure there's more than a few people that will be confused by something so feel free to ask. If there's pictures of anything in particular hit me up and I'll do my best to get them for you.
 

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Very nice write up and clean install! Definitely sticky material.
 

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Very nice write up. :thumbup: My VSV dropped dead last year and this is a very good replacement idea and a hell of a lot cheaper than replacing the VSV assembly. The one change I'll make is to use a solenoid operated valve so I can use a in dash switch.
 

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Discussion Starter · #6 ·
I wanted to get away from the electronically controlled valves. That's why I went with the manual switch. It does pose some issues with placement though. With the connectors and vacuum hose connected the whole assmbly ended up around 3" wide. Be careful with the vacuum hose connection at the actuator. For whatever reason mine used a slightly smaller ID hose than the rest of the system and slipped off a couple times when I got up to highway speeds
 

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Looks like my VSV has finally died on my '99 Holden Frontera (same as your Isuzu Rodeo), just posted a question on the forum then stumbled across this. Great work will look at doing something like this myself.

I was wondering if something like this could be done when i was trying to troubleshoot mine, and you have answered my question.

Cheers
 

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Discussion Starter · #8 ·
Yours may have an electronically controller axle. If it does this will not work yours. This is only for the vacu controlled axles.
 

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nasty610 said:
Yours may have an electronically controller axle. If it does this will not work yours. This is only for the vacu controlled axles.
Mine has the vacuum controlled one, think from memory the electronic one was introduced in 2001 in Australia.

Cheers
 
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