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Registered
1988 560sl
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208 Posts
Discussion Starter #1
i know the fuel door is activated by the vacuum module in the trunk. question is: what is the activation sequence? i assume that the engine vacuum keeps the door locked and released when the engine is shut off? any help with the operation procedure is appreciated. will have to add fuel to get it home. and yes, new owner here. going to pick it up tomorrow from a dealer who took it in on trade and who doesn't know anything about one. going to be a learn as i go process.;)
i'll post some pictures when i can.

thanks, jr.
 

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Premium Member
1975 450SL
Joined
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2,440 Posts
i know the fuel door is activated by the vacuum module in the trunk. question is: what is the activation sequence? i assume that the engine vacuum keeps the door locked and released when the engine is shut off? any help with the operation procedure is appreciated. will have to add fuel to get it home. and yes, new owner here. going to pick it up tomorrow from a dealer who took it in on trade and who doesn't know anything about one. going to be a learn as i go process.;)
i'll post some pictures when i can.

thanks, jr.
Welcome to the asylum!!:) Pull up a seat, grab a cold one, kick back and enjoy the show. We're here with tips, help, ideas, suggestions, and abuse as needed. There are a lot of people from all over the world, so you may find help is just around the corner.

If you fill in your profile with the year and model, we'll know exactly what generation of whichever system you're asking about to give you info on. There were a lot of changes over the years, so it can be important.

Scott
 

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Registered
79 450sl
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208 Posts
i know the fuel door is activated by the vacuum module in the trunk. question is: what is the activation sequence? i assume that the engine vacuum keeps the door locked and released when the engine is shut off? any help with the operation procedure is appreciated. will have to add fuel to get it home. and yes, new owner here. going to pick it up tomorrow from a dealer who took it in on trade and who doesn't know anything about one. going to be a learn as i go process.;)
i'll post some pictures when i can.

thanks, jr.
Don't know what model you are describing, but my 79 works this way. There is a line running through the driver's side around the firewall. It has a check valve to keep the pressure from bleeding back. The pressure comes from the manifold. Once through the firewall it goes to a vacuum container in the kick panel in the driver's side. To access the kick panel you have to first remove the hood release then trim and the panel should slide out. The air reservoir is covered by a plastic cover with a lot of screws. It's tough to get them all. The line then runs to the driver's door where there is a master cylinder. Three lines come off the master cylinder. I can't remember where each one goes, but i think one goes to the actuator on the drivers door, one to the passenger side. The line splits at the passenger side just under the glove box. I want to say that one line goes to the passenger door and the other one to the trunk area where it splits again. One line carries pressure to the trunk and one to the fuel door. The actuator for the fuel door is behind the jack on the right side of the trunk. The trunk itself has another actuator.

Turn the key in the drivers door one way and it locks all the actuators. Turn it the other way and pressure is released. I want to say that there should be enough pressure to lock and unlock the car six times. After that the pressure bleeds down. Mine has a small leak somewhere because it will lock the doors but after about 30 minutes it won't unlock all the doors. You have to restart the car to re-pressure the system since the pressure comes from the manifold.
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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32,345 Posts
Just to further confuse you the '86-'89 does not rely on engine vacuum.

Welcome to the asylum.
 

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Registered
1978 450SL--117K
Joined
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1,374 Posts
Just to further confuse you the '86-'89 does not rely on engine vacuum.

Welcome to the asylum.
I'll confuse him even more--my 78 does not have a vacuum reservoir on the driver's side under the kick panel--all the locking system uses is the reservoir in the front right wheel well. There are two check valves on the line just before it enters the fire wall, then it goes to the master in the drivers (left) door, then back out of the master and around to the other side (right) and into the passenger door as well as to the trunk were it goes to the fuel door, then the trunk lock--which I need to adjust somehow, because while it locks fine, it does not unlock via vacuum.

I had to replace every last vacuum pod and the master as well as the check valves to get it to work and hold pressure. Pretty cool once it does. But the 560 is definitely a superior upgrade.
 

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Registered
1988 560sl
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208 Posts
Discussion Starter #6
this is an "1988" 560sl. original paint, no dings,scratches,dents, etc. hardtop is the same. headliner in good condition. runs good. ran it up to 85mph on the freeway ( salesman aboard;)) and it tracked straight and smooth. everything seems to operate as it should. no upholstry issues such as tears, cracking,etc. plastic in the soft top is a little dull but not bad at all. no tears in the soft top. no rust isues that i could find . tires look almost new.
paid $9000 for it which i thought was good considering the good condition. 115k miles.

ok, back to the question. if it doesn't operate from a vacuum source is there a latch, switch somewhere?
i tried to open it with my fingers but they are too fat to get a grip on the flap and i didn't want to take a screwdiver to it before i knew what i was doing.

thanks'

jr
 

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Registered
'86 560SL 101,000 mi
Joined
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71 Posts
this is an "1988" 560sl. original paint, no dings,scratches,dents, etc. hardtop is the same. headliner in good condition. runs good. ran it up to 85mph on the freeway ( salesman aboard;)) and it tracked straight and smooth. everything seems to operate as it should. no upholstry issues such as tears, cracking,etc. plastic in the soft top is a little dull but not bad at all. no tears in the soft top. no rust isues that i could find . tires look almost new.
paid $9000 for it which i thought was good considering the good condition. 115k miles.

ok, back to the question. if it doesn't operate from a vacuum source is there a latch, switch somewhere?
i tried to open it with my fingers but they are too fat to get a grip on the flap and i didn't want to take a screwdiver to it before i knew what i was doing.

thanks'

jr
If its not turning when you unlock the car, you could maybe try going in through the boot? It's behind the same panel as the battery- passenger side.
 

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Registered
1987 560SL, 1998 SL500
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464 Posts
I do assume that you know that you do not open the door by pulling the back, but rather push in the front. But PeP is correct, in the battery compartment in the trunk at the top is a knob that you can pull and manually release the lock. Push in the front, and away you go. Welcome to the board, and like all has been suggested, fill in your profile then we would have known that it was a 560SL.
 

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Registered
1988 560sl
Joined
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208 Posts
Discussion Starter #9
I do assume that you know that you do not open the door by pulling the back, but rather push in the front. But PeP is correct, in the battery compartment in the trunk at the top is a knob that you can pull and manually release the lock. Push in the front, and away you go. Welcome to the board, and like all has been suggested, fill in your profile then we would have known that it was a 560SL.
thank you, i did not know that! like i stated, " it's going to be a learning process".
pofile updated.
 

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It Is What It Is, Dude
Joined
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22,841 Posts
this is an "1988" 560sl. original paint, no dings,scratches,dents, etc. hardtop is the same. headliner in good condition. runs good. ran it up to 85mph on the freeway ( salesman aboard;)) and it tracked straight and smooth. everything seems to operate as it should. no upholstry issues such as tears, cracking,etc. plastic in the soft top is a little dull but not bad at all. no tears in the soft top. no rust isues that i could find . tires look almost new.
paid $9000 for it which i thought was good considering the good condition. 115k miles.

ok, back to the question. if it doesn't operate from a vacuum source is there a latch, switch somewhere?
i tried to open it with my fingers but they are too fat to get a grip on the flap and i didn't want to take a screwdiver to it before i knew what i was doing.

thanks'

jr

The GenII central locking system is vacuum operated, but vacuum is supplied by an electric pump located in the trunk(?) rather than manifold vacuum.
 
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