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PointedThree :  Vans, Trucks, SUVs and Other Forums : G-Class : '02 G500 Differential Lock System

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'02 G500 Differential Lock System
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Author
Posted 1/22/2012 10:11 AM
nadd
Expert




Date registered: Apr 2006
Location: UAE, Dubai
Vehicle(s): G500 2016 LHD, numerous Chevys
Posts: 1285
1000
RE: '02 G500 Differential Lock System

Great to hear you sorted it out in the end, even though the process was a bit lengthy!

I have a question somewhat related to this post, this is on the G500, as my initial symptom is to do with bleeding the fronts, the rear cylinder bled fine but when I came to the front (using the vacuum method) no fluid would come out.

I removed the bleed screw completely and still nothing would come out, even while engaging the front diff switch.
The funny thing is the front diff lock engages/disengages fine (both the red light comes on and I can confirm it with the front jacked up), so there must be fluid moving in there, but not near the bleed screw.

Has anyone tried taking off the end part of the cylinder (1 in the picture) while still mounted on the car? I read elsewhere (was it a DIY post?) about this being done in a vice on the bench, so did not want to open it on the car in the driveway and not be able to put it back together. I want to avoid removing the diff from the axle for fear of not putting it back in the right position.

Image courtesy of fourbyfourclub's website free download area - thanks!



(difflockparts.jpg)



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Attachments difflockparts.jpg (175KB - 1 downloads)
#199587 - in reply to #173877
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Author
Posted 2/5/2012 12:04 AM
Indiana Drew
Expert




Date registered: Feb 2007
Location: Houston Tx
Vehicle(s): 2002 G500 LWB, 1980 280GE SWB (Sold), S500
Posts: 2223
2000
RE: '02 G500 Differential Lock System

The front is gone again - it might be the alignment again ... Have you taken your apart yet? I believe there is a rebuild kit, but maybe  you bleed is just cloged? Let us know what you find ...
#200085 - in reply to #199587
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Posted 2/5/2012 6:38 AM
nadd
Expert




Date registered: Apr 2006
Location: UAE, Dubai
Vehicle(s): G500 2016 LHD, numerous Chevys
Posts: 1285
1000
RE: '02 G500 Differential Lock System

Indiana Drew - 2/5/2012 5:04 AM

The front is gone again - it might be the alignment again ... Have you taken your apart yet? I believe there is a rebuild kit, but maybe  you bleed is just cloged? Let us know what you find ...


Hadn't had the chance this time, hopefully next time I'm with the car in Dubai, in a couple of months time, I'll get all the necessary seals/gaskets and be brave enough to take it apart.
#200095 - in reply to #200085
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Author
Posted 2/10/2019 4:20 AM
bnZE430/1999
Member


Date registered: Dec 2016
Location: SF Bay Area
Vehicle(s): 2002 G500 w463
Posts: 30
25
Re: '02 G500 Differential Lock System

Hey guys,

I know this is an old post but I wanted to share some of my findings and hopefully I can get my locks to work too. Truck is a 2002 G500.

I had all amber lights in the beginning. I used the forum and found that the elbow under the fender was broken. Fixed that so I got center light to turn red but the front and rear will not turn red.

Earlier I took the good advice of some on this forum and decided to use a power bleeder (tank) to bleed the actuators. The old fluid in the reservoir looked dark brown. I suctioned out the old fluid out using a turkey baster and replaced it with MB dot 4 plus fluid. With 15 psi in the tank I couldn’t get anything to come out from the front or rear. After about an hour I got fluid slowly in the rear and eventually bled the actuator. The front had gunk and debris that took forever to clean out (about another hour). I had clean fluid flowing and I cleaned the gunked up banjo fitting bolt. Actuators look like they’ve been seeping for a while.

I still can not get lock up or a red light. I manually checked and neither front nor rear axles were locked. Any ideas?

Thanks in advance
#240424 - in reply to #173877
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Author
Posted 2/10/2019 6:50 AM
DUTCH
Administrator Doppelgänger




Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
5000
Re: '02 G500 Differential Lock System

bnZE430/1999 - 2/10/2019 4:20 AM

Hey guys,

I know this is an old post but I wanted to share some of my findings and hopefully I can get my locks to work too. Truck is a 2002 G500.

I had all amber lights in the beginning. I used the forum and found that the elbow under the fender was broken. Fixed that so I got center light to turn red but the front and rear will not turn red.

Earlier I took the good advice of some on this forum and decided to use a power bleeder (tank) to bleed the actuators. The old fluid in the reservoir looked dark brown. I suctioned out the old fluid out using a turkey baster and replaced it with MB dot 4 plus fluid. With 15 psi in the tank I couldn’t get anything to come out from the front or rear. After about an hour I got fluid slowly in the rear and eventually bled the actuator. The front had gunk and debris that took forever to clean out (about another hour). I had clean fluid flowing and I cleaned the gunked up banjo fitting bolt. Actuators look like they’ve been seeping for a while.

I still can not get lock up or a red light. I manually checked and neither front nor rear axles were locked. Any ideas?

Thanks in advance


You probably need to remove the slaves and clean or rebuild them.
#240425 - in reply to #240424
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Author
Posted 2/10/2019 10:33 AM
paulunm
Veteran


Date registered: Jan 2015
Location: Los Angeles
Vehicle(s): 2000 G500
Posts: 124
100
Re: '02 G500 Differential Lock System

You might also check the vacuum lines to the intensifiers to see if they're full of fluid. If so, new intensifiers.
#240426 - in reply to #240425
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Author
Posted 2/11/2019 12:59 PM
AlanMcR
Expert




Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
2000
Re: '02 G500 Differential Lock System

Given that it is basically free to exercise the system, that is what I would do for several days in a row.  Find a stretch of dirt and turn on all the lockers, move forward slowly for 20 seconds, turn off, repeat.  If the cylinders break free you are home free, if not, you are no worse off. 

You are absolutely sure that vacuum is getting to the intensifiers?

The center diff locks up successfully?

 

#240427 - in reply to #240424
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Posted 2/11/2019 4:53 PM
bnZE430/1999
Member


Date registered: Dec 2016
Location: SF Bay Area
Vehicle(s): 2002 G500 w463
Posts: 30
25
Re: '02 G500 Differential Lock System

Hello guys... the center diff locks after I changed the plastic elbow. (See attached picture)


I pulled the vacuum line off the bottom of the intensifier and they look bone dry. (See attached picture).


Edit: I will update the pics

Edited by bnZE430/1999 2/11/2019 5:00 PM
#240428 - in reply to #173877
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Posted 2/11/2019 8:02 PM
4x4abc



Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
5000
RE: '02 G500 Differential Lock System

I use my diff locks regularly and they work perfectly
time to change the fluid though
have not done in in 15 years

I had a couple of episodes when they refused to lock
in each case the culprit was an elbow on the firewall distributor
see the read arrows in the image

none available in Mexico, so I had to improvise
used a standard rubber hose
problem is that the elbow has 2 different inner diameters
had to make one inlet on the rubber hose larger

did a field fix twice by using silicone and a zip tie to close the crack in the elbow

the cracks might be very small and thus hard to locate



(elbow.jpg)



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Attachments elbow.jpg (192KB - 3 downloads)
#240433 - in reply to #173877
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Posted 2/11/2019 8:08 PM
4x4abc



Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
5000
RE: '02 G500 Differential Lock System

also - there are 3 check valves between the pump and the register
they get brittle and old
so, the vacuum line might not be working when a check valve fails
only a few bucks at the dealer



(check.jpg)



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Attachments check.jpg (80KB - 2 downloads)
#240434 - in reply to #173877
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Posted 2/12/2019 11:39 AM
paulunm
Veteran


Date registered: Jan 2015
Location: Los Angeles
Vehicle(s): 2000 G500
Posts: 124
100
Re: '02 G500 Differential Lock System

Herald, where exactly are these check valves? On the firewall?
#240442 - in reply to #240434
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Posted 2/12/2019 9:37 PM
AlanMcR
Expert




Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
2000
Re: '02 G500 Differential Lock System

High on the firewall, just to the drivers side of the fresh air scoop.
#240446 - in reply to #240442
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Posted 2/13/2019 1:29 PM
4x4abc



Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
5000
RE: '02 G500 Differential Lock System

here we go



(check.jpg)



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Attachments check.jpg (184KB - 2 downloads)
#240447 - in reply to #173877
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Posted 2/13/2019 1:32 PM
4x4abc



Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
5000
RE: '02 G500 Differential Lock System

in the background you see one of the silicone + zip tie "fixed" elbows that tend to crack



(fix.jpg)



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#240448 - in reply to #173877
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Posted 2/13/2019 1:57 PM
paulunm
Veteran


Date registered: Jan 2015
Location: Los Angeles
Vehicle(s): 2000 G500
Posts: 124
100
Re: '02 G500 Differential Lock System

Ah those guys! Happen to have a part number for them? All the same for all three I assume?

And yes, those elbows don't seem to hold up very well in hot/dry environments. Part number for those is-

1170780781
#240449 - in reply to #240447
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Posted 2/13/2019 2:51 PM
4x4abc



Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
5000
RE: '02 G500 Differential Lock System

check valves A 123 800 00 78



Edited by 4x4abc 2/13/2019 2:59 PM
#240450 - in reply to #173877
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Posted 2/14/2019 11:24 PM
4x4abc



Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
5000
RE: '02 G500 Differential Lock System

found one of the images of the elbow crack during a trip



(vacuum elbow crack.jpg)



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Attachments vacuum elbow crack.jpg (158KB - 2 downloads)
#240453 - in reply to #173877
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Posted 2/15/2019 7:59 AM
DUTCH
Administrator Doppelgänger




Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
5000
Re: '02 G500 Differential Lock System

paulunm - 2/12/2019 11:39 AM

Herald, where exactly are these check valves? On the firewall?


Here they are on a pre-MBUSA 2000 G500.




(DSC00195_DxO.jpg)



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Attachments DSC00195_DxO.jpg (114KB - 3 downloads)
#240458 - in reply to #240442
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Posted 2/22/2019 9:48 PM
W5YK
Extreme Veteran




Date registered: May 2006
Location: San Diego
Vehicle(s): 2002 G500, Unimog U2450,
Posts: 543
500
Re: '02 G500 Differential Lock System

If you are suspicious that you have a leak in your diff vacuum lines (and you should be!) - there is a simple self-test you can do.

Turn the key to the first position, don't start the engine.
Select the center locker.
The vacuum pump should come on. It is a loud rattle straight in front of the driver.
After 30 seconds the pump will turn itself off, indicating that it reached a good vacuum, and all the vacuum lines up to the center diff are good.
If the pump runs forever, you have a leak.

Then you can start the engine, get the center diff engaged, turn off, and select the rear locker. If the pump stoops after 30 s that line is also good. Same for front. The system does not open up the vacuum lines for the next locker until the previous one is engaged, so you have to do this in a sequence.

If you do have a leak, you should replace all the check valves as suggested above, because they will be full of dirt and won't work.

Edited by W5YK 2/22/2019 9:50 PM
#240464 - in reply to #173877
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