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1999 Geo Tracker Front Differential Engaging?


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I just purchased a 1999 geo tracker 4x4 and it drives and runs good but needs a lot of TLC i dont think the front drive diff is engaging the light comes on on the instrument cluster saying 4x4 in high or low and goes iff in 2wd looks normal but dint seem to be pulling while in 4x4 and i found the air pump just laying behind the front head light air line from it going nowhere and all wiring not properly connected whats do you professional guys think about all this ?

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Tate10...Congrats on buying a 1999 Geo Tracker 4x4!  Sounds like the front axle disconnect system is not working.  You found the loose air pump, so it's not operating the system.  The disconnect clutch cannot engage and disengage. 

Below is a diagram of the 1999 Geo Tracker front axle and vacuum disconnect system.  The first order of business when we buy a vehicle is to get a quality (ideally factory) workshop manual for troubleshooting and service work.  For your 1999 Tracker, try to find a new or used manual.  The front axle troubleshooting flow chart will walk through the diagnostic steps. 

Others here at the forums will respond to your questions to speed up your troubleshooting...Moses

Carrier & Front Axles for 1999 Chevrolet Tracker | GM Parts Online

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  • Knyte changed the title to 1999 Geo Tracker Front Diff Engaging ?
On 1/6/2022 at 8:25 PM, Knyte said:

Hi Tate10, I moved your query to its own thread to get more eyes on it.

Thanks makes more since to have its own place since ill be working on this thing off and in for a while.

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Tate10...When you have a chance to install the pump and check out the hoses, let us know whether the front axle engages and disengages.  If you need to troubleshoot the front differential clutch without using the pump, I can suggest ways to do so.

Moses

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21 hours ago, Moses Ludel said:

Tate10...When you have a chance to install the pump and check out the hoses, let us know whether the front axle engages and disengages.  If you need to troubleshoot the front differential clutch without using the pump, I can suggest ways to do so.

Moses

Ok thanks this weekend I crawled all under the tracker inspected everything i could and there is no where on my front diff to hook air lines only hose on it was the vent line looks like maybe my diff has the air actuator removed from what i been reading i may just have Hub issues but it for sure isn’t pulling i got stuck hauling a deer out of my field this weekend so guess ill have to keep checking but after hunting season lol

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I think removing the actuator is a somewhat common mod.  After reading your post, I searched around a bit and found another forum where a few folks were chatting about the details of such.  From the sounds of it, the air actuators are if-y on the reliability meter, so people just remove it, lock the actuator ring with a spacer or zip tie(s), and add manual hubs.

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  • Moses Ludel changed the title to 1999 Geo Tracker Front Differential Engaging?
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Tate10...To get you oriented to the 1999-up Tracker front axle and how the actuator locks up at the differential, review this useful video from YouTube by "MrSputnik1988".  He offers a very good explanation and details on how the actuator system works plus details on one aftermarket cure that eliminates the failure prone actuator diaphragm.  Many do this conversion and install free-wheeling manual hubs for eliminating drag at the front axle and driveline.  (I've seen videos of the actuator clutch being welded in the locked position, an option involving high heat that could damage sensitive, hardened steel parts.  The spacer washer seems a less complicated and lower risk approach.)  The actuator is a common source of trouble.  Here is MrSputnik1988's informative video.  At YouTube, note the one viewer's comment about the 4WD light.  Make sure the 4x4 light will operate after installing the spacer washer kit:

You can test the actuator function with the Tracker's engine shut off and axle/wheels safely off the ground with safety jack stands supporting the chassis or axle segments.  Apply compressed air at a very low PSI.  (Actual pressure output from the pump cuts off at 6 PSI, which should be regarded as the PSI ceiling.)  Do not apply excess pressure, or you can damage the actuator diaphragm. 

Here is an excellent set of drawings and schematics for your 1999 Tracker system.  The first illustration represents your '99 application, which according to the diagram and author's details does not involve the PCM.  This would be a big plus:

https://chevroletforum.com/forum/tracker-26/tracker-101-intro-4wd-air-pump-102819/

Front axle disconnect systems from various vehicle manufacturers were designed to 1) remove the need for manual or automatic free-wheeling hubs and 2) to help eliminate ring gear/carrier and front driveline parasitic drag in 2WD mode.  Every application of these axle disconnects has either failure prone parts or significant challenges when performing service work on the front axle. 

Free-wheeling hubs for 4x4s have been around since the 'fifties.  I grew up manually locking and unlocking front wheel hubs.  My mother was an R.N. who worked graveyard shifts and commuted in our 1964 Jeep CJ-5 4x4 during Eastern Sierra snowstorms.  She locked and unlocked the Cutlas hubs as necessary...Other four-wheel-drive owners should be able to get out of the vehicle to lock-in or free the hubs when required.

Moses

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1 hour ago, Moses Ludel said:

Tate10...To get you oriented to the 1999-up Tracker front axle and how the actuator locks up at the differential, review this useful video from YouTube by "MrSputnik1988".  He offers a very good explanation and details on how the actuator system works plus details on one aftermarket cure that eliminates the failure prone actuator diaphragm.  Many do this conversion and install free-wheeling manual hubs for eliminating drag at the front axle and driveline.  (I've seen videos of the actuator clutch being welded in the locked position, an option involving high heat that could damage sensitive, hardened steel parts.  The spacer washer seems a less complicated and lower risk approach.)  The actuator is a common source of trouble.  Here is MrSputnik1988's informative video.  At YouTube, note the one viewer's comment about the 4WD light.  Make sure the 4x4 light will operate after installing the spacer washer kit:

You can test the actuator function with the Tracker's engine shut off and axle/wheels safely off the ground with safety jack stands supporting the chassis or axle segments.  Apply compressed air at a very low PSI.  (Actual pressure output from the pump cuts off at 6 PSI, which should be regarded as the PSI ceiling.)  Do not apply excess pressure, or you can damage the actuator diaphragm. 

Here is an excellent set of drawings and schematics for your 1999 Tracker system.  The first illustration represents your '99 application, which according to the diagram and author's details does not involve the PCM.  This would be a big plus:

https://chevroletforum.com/forum/tracker-26/tracker-101-intro-4wd-air-pump-102819/

Front axle disconnect systems from various vehicle manufacturers were designed to 1) remove the need for manual or automatic free-wheeling hubs and 2) to help eliminate ring gear/carrier and front driveline parasitic drag in 2WD mode.  Every application of these axle disconnects has either failure prone parts or significant challenges when performing service work on the front axle. 

Free-wheeling hubs for 4x4s have been around since the 'fifties.  I grew up manually locking and unlocking front wheel hubs.  My mother was an R.N. who worked graveyard shifts and commuted in our 1964 Jeep CJ-5 4x4 during Eastern Sierra snowstorms.  She locked and unlocked the Cutlas hubs as necessary...Other four-wheel-drive owners should be able to get out of the vehicle to lock-in or free the hubs when required.

Moses

Thanks thats a lot of good info but my tracker has had to many idiots working on it lol everything is unhooked and or missing the 4x4 light on dash comes on when i put transfer case in 4 low or high like everything is good but frontend not pulling like i said imma wait till i get my Honda pioneer engine back together so i will have a way to get around my farm and deer season is over im pulling the hubs first see if they are the issue and I already know i’m not going to be that lucky hahaha so i will be trying to find that spacer sputnix used i think that’s what he goes by in the video I’m kinda nervous about welding on the gears i can weld it with nickel rods but the heat is what bothers me about that fix. 
thanks again for the help

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Tate10...I agree about welding on the gears.  I would not weld on the differential if the spacer washer is only a $20 part.  The differential and ring gear parts are case hardened and will lose their case.  No matter how you weld it, the heat affected zone (HAZ) alongside the weld will lose its case hardening.

MrSputnik1988 uses the washer/spacer instead, and he shows that fix in the 20-minute video.  When you get the Pioneer project done, take a peek at his video.  It clearly explains what you're dealing with, and he mentions the spacer manufacturer by name several times.  If you click on "YouTube" at the video, it will go directly to his comments at YouTube. 

Tackle the Pioneer engine.  We're here when you get ready to work on the Geo Tracker.

Moses 

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