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Recently picked up a 2013 G63 and while center and rear lockers engage, front does not. I bled the line today, but front still won't come on.
I am thinking about removing the actuator from the axle and cleaning it? Any idea if removing the actuator will dump the fluid out, or is there a one-way valve that will keep the fluid in the line intact?
If that doesn't help, what's next? Replace actuator itself? Are the actuators for front and rear axle same part number, if I need to look on eBay?
At the vacuum pump (driver's side engine bay front), there are two vacuum lines going into the pump. Those could be mis-connected also. Someone can chime in with the proper way to identify which is which and if that also has any effect.
There's also vacuum collectors under the front left wheel well liner, there could be this little white plastic L fitting that sometimes breaks and leaks air. Check that too. It looks like two black ***** (that's what she said) with a vacuum line going in.
At the vacuum pump (driver's side engine bay front), there are two vacuum lines going into the pump. Those could be mis-connected also. Someone can chime in with the proper way to identify which is which and if that also has any effect.
There's also vacuum collectors under the front left wheel well liner, there could be this little white plastic L fitting that sometimes breaks and leaks air. Check that too. It looks like two black ***** (that's what she said) with a vacuum line going in.
I think since his center and rear lockers are working, the vacuum reservoir is likely ok.
This link is great, has a helpful diagram of the system-
Thank you, I did more troubleshooting. Here is what I found:
Took the actuator itself apart and cleaned it with carb cleaner. Everything looks good and moves freely by hand.
Unplugged the second vac line at the switchover valve (per that PDF, thats the front diff lock) in the engine bay and heard a hissing sound.
Took the wheel well liner off and inspected. I didn't see any lines loose though I did find two electrical connectors not plugged into anything! See pics.
Inspected the pressure intensifier units in the driver's side frame rail. Unplugged the line that goes into the front diff intensifier that's marked "from switchover valve" in the PDF. Oil started flowing from it so I plugged it back in. See pic.
Have you verified vacuum is present at the axle? Have you thought about a hand vacuum pump (Lisle 75000 or similar from Mityvac) to definitively apply vacuum?
Have you verified vacuum is present at the axle? Have you thought about a hand vacuum pump (Lisle 75000 or similar from Mityvac) to definitively apply vacuum?
I am not sure how to verify "vacuum is present at the axle" if you can show me how, I can do that. On the front locker actuator, there are two banjo bolts - one at the top, and one one the side right by the bleeder valve. I undid the one at the top and it was dry and I undid the one by the bleeder and fluid came out. Other than that, I am unsure how to check vacuum.
When I was by the intensifier, I unplugged the hose at the bottom of both front and rear axle intensifiers - in the diagram from the schematic, these hoses are labeled "from switchover valve" - both lines from both intensifiers spewed oil.
Since both the vacuum lines of my rear and front intensifiers have oil, I assume both intensifiers are toast. Anyone have part numbers for these contraptions?
Since my rear locker is still working, is it fair to assume the intensifier has not completely failed yet but is on its way out?? (there is oil in the vac line in both intensifiers)
Yeah, I'd agree your intensifiers are bad if there's fluid in the vacuum lines. So replace the intensifiers but you'll also need to get fluid out of the vacuum lines going to the intensifiers as well.
When the intensifier fails, the vacuum system sucks fluid up into the lines... not easy to get out- I ended up having a shop do the intensifiers and get all the fluid out of the lines...
I swapped the vacuum output line from rear locker to front. Front locked and rear did not.
Culprit is this guy:
Before I replace this, I want to ensure its not a blown fuse. Owner's manual says page 229 has a fuse chart and it does not. Owner's manual also says driver's side fuse box should be here (and it is not. Behind that panel is just a bunch of wires plugged in):
I looked at all the fuses in the passenger footwell area and none of them are blown. Anyone got any clues as to where the diff lock fuses would be in a 2013 G63??
I swapped the vacuum output line from rear locker to front. Front locked and rear did not.
Culprit is this guy:
Before I replace this, I want to ensure its not a blown fuse. Owner's manual says page 229 has a fuse chart and it does not. Owner's manual also says driver's side fuse box should be here (and it is not. Behind that panel is just a bunch of wires plugged in):
I looked at all the fuses in the passenger footwell area and none of them are blown. Anyone got any clues as to where the diff lock fuses would be in a 2013 G63??
Congrats on the vacuum diagnosis. Do G-Wagens have a paper folded-up fuse assignment document in one of the fuse boxes? GLE/GLS have this in the fuse box under the rear right (passenger rear) seat.
Nice work diagnosing your locker issue. I need to do the same as my rear was sticking when I used it last (way too long ago unfortunately).
Interesting that your driver side fuse box isn't in the side of the dash since I definitely have one there in my 2005. Maybe something changed in the 2013+ interior refresh years?
OK here's an update. I got a new air control valve / solenoid and installed it. All 3 lockers locked immediately.
But not celebrating yet because I now have a new problem. When I dis-engaged the lockers (click the buttons off, red lights turn off followed by yellow lights turning off) and then re-engaged, none of the lockers will come back on. I have since tried shifting out of 4 Low into High, then back to Low, turning, etc. Nada, none of the red lights will engage. Any clues?!?!
Last edited by xxaarraa; May 13, 2023 at 11:20 PM.
OK here's another update and hopefully a happy ending to my saga.
Not satisfied with the inconsistent performance of the lockers, I went back to basics:
Cleaned out every solenoid connector with contact cleaner.
Checked vacuum for center, rear and front.
Dis-assembled lock slave cylinders, cleaned, disconnected hard lines from flex lines (disconnected the hard line at intensifier to each axle and blew out with compressed air - got a lot of gunk out).
Re-assembled and rebled.
All seems OK for now, will keep an eye out and report back in future. I do sincerely hope that the days of crawling underneath and having warm RBF660 pour all over me while quickly assembling a slave cylinder are behind me, haha.
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