Strange tailgate problem
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Mercedes ML320 CDI
Strange tailgate problem
Hello I have an issue with my 2009 GL 500.My tailgate isn’t working properly for a couple of years. It started one summer when it was very hot. The tailgate opens fine from the fob, the tailgate knob and the button which is inside the car but it won’t close from any of them. It can be closed only by hand. When is nearly closed the hydraulic pump does its job and shuts the tailgate closed. This problem disappeared during the winter. I could open and close the tailgate no problem. This summer the problem appeared again. When I tried to close it from the fob there is a sound coming from the lock like it is trying to lock itself but the tailgate doesn’t move. The tailgate opens fine every time but I can’t close it any other way except by hand. When the car cools off after a couple of tries it works. My local dealer can’t fix the problem no matter how many times I bring the car in. Has anyone run into the same problem? I would really appreciate some kind of tip what is causing the problem. Thank you
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NGL450 w/EORP, S550
Hello I have an issue with my 2009 GL 500.My tailgate isn’t working properly for a couple of years. It started one summer when it was very hot. The tailgate opens fine from the fob, the tailgate knob and the button which is inside the car but it won’t close from any of them. It can be closed only by hand. When is nearly closed the hydraulic pump does its job and shuts the tailgate closed. This problem disappeared during the winter. I could open and close the tailgate no problem. This summer the problem appeared again. When I tried to close it from the fob there is a sound coming from the lock like it is trying to lock itself but the tailgate doesn’t move. The tailgate opens fine every time but I can’t close it any other way except by hand. When the car cools off after a couple of tries it works. My local dealer can’t fix the problem no matter how many times I bring the car in. Has anyone run into the same problem? I would really appreciate some kind of tip what is causing the problem. Thank you
There are two separate hydraulic circuits-one for opening and one for closing. You’ve a leak in the closing circuit somewhere and there’s not enough hydraulic fluid left in that circuit to actuate the gate closing.
I just live with it, it’s still a functioning tailgate and closes fine by hand.
Repair usually means taking apart the back interior sidewalls, load floor and headliner to find the leak = $$$ in labor.
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Mercedes ML320 CDI
Yes, one of mine does this.
There are two separate hydraulic circuits-one for opening and one for closing. You’ve a leak in the closing circuit somewhere and there’s not enough hydraulic fluid left in that circuit to actuate the gate closing.
I just live with it, it’s still a functioning tailgate and closes fine by hand.
Repair usually means taking apart the back interior sidewalls, load floor and headliner to find the leak = $$$ in labor.
There are two separate hydraulic circuits-one for opening and one for closing. You’ve a leak in the closing circuit somewhere and there’s not enough hydraulic fluid left in that circuit to actuate the gate closing.
I just live with it, it’s still a functioning tailgate and closes fine by hand.
Repair usually means taking apart the back interior sidewalls, load floor and headliner to find the leak = $$$ in labor.
Thank you for the answer. I will probably try to fix it because I open and close the tailgate around 10-15 times per day and it kind of a nuisance. I just wonder why does it work in cold weather and it doesn’t when its hot outside?
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Joined: Mar 2009
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From: CT
GL 450, 993TT, Cayenne Diesel, 964C4
My GL320 had the opposite issue. It would work in the summer but not winter. Adjust the rubber knobs on the rear frame above the lights. I had to extend them in the winter as cold weather shrunk them. The lift gate sensor will not actuate if there is too much or little tension when it first comes in contact with the latch.
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NGL450 w/EORP, S550
Since you have a leak you have air in the system and
that air bubble and is denser and less compressible when it is cold
as the ambient temperature increases so does the volume of the air trapped in the system, and the system loses hydraulic power as that air becomes less dense and more compressible.
You might get lucky - the pump and reservoir sits under the spare tire and ports pressurized fluid through two circuits to actuators in the ceiling. If the leak is near the pump you may find hyd fluid there. Easier fix than;
If it is in the actuators you may have hyd fluid dripping down the inside of the headliner along the right rear d-pillar onto the subwoofer and rear fuse block. Headliner needs to come out to address this.
OHBTw: you said you are able to close it by hand - you should not be able to do this with a fully charged system, which is why I think you have a leak.
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Mercedes ML320 CDI
Thermodynamics. Pressure Volume Temperature interaction.
Since you have a leak you have air in the system and
that air bubble and is denser and less compressible when it is cold
as the ambient temperature increases so does the volume of the air trapped in the system, and the system loses hydraulic power as that air becomes less dense and more compressible.
You might get lucky - the pump and reservoir sits under the spare tire and ports pressurized fluid through two circuits to actuators in the ceiling. If the leak is near the pump you may find hyd fluid there. Easier fix than;
If it is in the actuators you may have hyd fluid dripping down the inside of the headliner along the right rear d-pillar onto the subwoofer and rear fuse block. Headliner needs to come out to address this.
OHBTw: you said you are able to close it by hand - you should not be able to do this with a fully charged system, which is why I think you have a leak.
Since you have a leak you have air in the system and
that air bubble and is denser and less compressible when it is cold
as the ambient temperature increases so does the volume of the air trapped in the system, and the system loses hydraulic power as that air becomes less dense and more compressible.
You might get lucky - the pump and reservoir sits under the spare tire and ports pressurized fluid through two circuits to actuators in the ceiling. If the leak is near the pump you may find hyd fluid there. Easier fix than;
If it is in the actuators you may have hyd fluid dripping down the inside of the headliner along the right rear d-pillar onto the subwoofer and rear fuse block. Headliner needs to come out to address this.
OHBTw: you said you are able to close it by hand - you should not be able to do this with a fully charged system, which is why I think you have a leak.
Thread Starter
Newbie
Joined: Nov 2012
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Mercedes ML320 CDI
My GL320 had the opposite issue. It would work in the summer but not winter. Adjust the rubber knobs on the rear frame above the lights. I had to extend them in the winter as cold weather shrunk them. The lift gate sensor will not actuate if there is too much or little tension when it first comes in contact with the latch.
