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4 Wheel Drive/SUVs/VACUUM SYSTEM FOR 4X4 CHEVY TRANSFER CASE

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Expert: - 11/26/2004


Question
The vacuum hose seems to collapse keeping the wheels locked in. I have to pull the hose off to run in two wheel.The diagram shows a check valve in the vacuum source line. What is the reason for this? There is not one on my truck.I replaced the source hose and found a tee in the line. I thought this was causing a vacuum loss so I didn't put it back on. This is a 1985 Chevy S-10. Thanks in advance.

Answer
Tom,

Sounds like your line, is not a vacuum line.  A line designed for vacuum shouldn't collapse.  The vehicle doesn't develop enough vacuum to collapse a vacuum line.  As far as the tee goes, if one was in line, then it should have been connected to something.  If it was open, you would, definitely, have a vacuum leak.  Actually, just pulling the vacuum line off, should not shift the front end out of 4-wheel.  I'm not real familiar with Chevys, but most of these systems work off of a vacuum switch, located on the transfer case, that switches the vacuum from one line to another, allowing it to shift in and out of 4-wheel drive.

I would suggest that you purchase a repair manual for your rig, and trace out the vacuum lines, and replace any that seem to be collapsing with new lines.   Chilton's or a Hayne's manual can be purchased at most auto parts stores for $20.  They have a lot of information on basic trouble shooting, and repairs, including a list of special tools that may be needed for a specific job, nut sizes along with torque settings.  These manuals are designed for a year or range of years for specific vehicles, and are invaluable if you are planning on doing any repairs, or maintenance yourself.

Carl

4 Wheel Drive/SUVs

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Carl Brandt

Expertise

Will discuss suspensions, lifts, lockers along with tire suggestions. Trail ratings and possible requirements needed for specific type of trails. Safety equipment and what you should carry with you. Certified off-road instructor. I am not a mechanic, and 4-Wheeling is a hobby, so if I can't answer a technical question it is due to my mechanical knowledge being related to vehicles that I have owned, or have worked on. I do not have manuals on all vehicles.

Experience

40 plus years of 4 wheeling in a variety of vehicles. At the present time, my major off-road rig is a 94 Jeep Wrangler with a spring over and a 1 1/2" suspension lift. This gives me a total lift of 7" or so. I have lockers front and rear. I have removed the track bars, and sway bar for maximum articulation. I am running a stock 2.5 ltr 4 cylinder with a Jacobs ignition along with a cold air high flow filter. It has 4.56:1 gears with a Dodge NV4500 transmission along with a 3.8:1 Atlas II transfer case. This gives me a final ratio of 105:1 in low gear/low range. Other vehicles I own, are a 96 Ford F-250 with a 6" lift, posi rear end, 36" Hummer tires, 5 speed with a fuel injected 460 ci engine, an 87 Samurai with an 8" lift, Ford 9" rear end with a spool, Chevy Dana 44 front end with an electric locker, 5.88 gears, 16% reduction in high range and a 6.5:1 low range with 35" Baja Claws, and a stock 2003 Grand Cherokee Overland. Trails I have run are the Rubicon (10 times), Dusey Ershim, Fordyce Creek trail, McGrew trail, several trails in Moab, Utah along with local monthly runs.

Organizations
Lost Coast 4x4's Cal 4-Wheel Corva UFWDA Blue Ribbon Coalition

Education/Credentials
Certified off-road instructor - Certificates in engineering/electronics

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