SL/R129: New owner with a couple of questions and an issue
Thread Starter
Newbie
Joined: Feb 2009
Posts: 4
Likes: 1
From: Glasgow
SL320
New owner with a couple of questions and an issue
Hi Folks, long time lurker here. After owning several (8!) SLK's I've taken the plunge and bought a beautiful black/green R129 SL320 with the panoramic roof. It's one of the last straight sixes built and registered in early 1998.
Here's my questions. The windows do one touch down but not up, is this correct? Another thing I'm experiencing is a hard top problem. When I picked the car up I tested the soft top and it worked fine multiple times, we then fitted the hard top with no issues. Now a week later when I tried to remove the hard top, if I pull the button to release the top nothing happens except the button red light flashes, but, if I push it forward it engages and pulls it back down. Very strange!
Everything else is working fine, I have reset the windows (still only one touch down) they drop (10mm or so) for the doors opening, roll bar operation fine too. I have also unplugged the heated rear plug. Any ideas anyone?
I will add the boot struts are a bit weak (ordered) but hold the boot (trunk) open ok. But what is the push button switch on the rear panel? Could that be a possible problem?
In the meantime I have disconnected the battery (- side only!) and checked the battery voltage which was 12.4v disconnected, it was 13.7 connected and running.
Any help/advice greatly appreciated.
Here's my questions. The windows do one touch down but not up, is this correct? Another thing I'm experiencing is a hard top problem. When I picked the car up I tested the soft top and it worked fine multiple times, we then fitted the hard top with no issues. Now a week later when I tried to remove the hard top, if I pull the button to release the top nothing happens except the button red light flashes, but, if I push it forward it engages and pulls it back down. Very strange!
Everything else is working fine, I have reset the windows (still only one touch down) they drop (10mm or so) for the doors opening, roll bar operation fine too. I have also unplugged the heated rear plug. Any ideas anyone?
I will add the boot struts are a bit weak (ordered) but hold the boot (trunk) open ok. But what is the push button switch on the rear panel? Could that be a possible problem?
In the meantime I have disconnected the battery (- side only!) and checked the battery voltage which was 12.4v disconnected, it was 13.7 connected and running.
Any help/advice greatly appreciated.
Thread Starter
Newbie
Joined: Feb 2009
Posts: 4
Likes: 1
From: Glasgow
SL320
Wee update. Got to the bottom of the hard top removal issue. I found out that I had to pull the roof button within 10 or so seconds of turning on the ignition. Tried that and it worked right away. Gave a bit of a bang as it released the lock above my head (RHD) but that's easy to live with.
Last edited by BILLY610; Sep 17, 2025 at 11:19 AM. Reason: Typo
Junior Member
Joined: Sep 2015
Posts: 29
Likes: 1
From: NY
1997 S500, 99 SL500, 88 560SL, 87 BMW 635
Wee update. Got to the bottom of the hard top removal issue. I found out that I had to pull the roof button within 10 or so seconds of turning on the ignition. Tried that and it worked right away. Gave a bit of a bang as it released the lock above my head (RHD) but that's easy to live with.
Super Member
Joined: Jul 2016
Posts: 704
Likes: 129
From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
R129 parts
Congrats on buying a great car. Wanted to let you know my son has a large R129 parts store on ebay
“thebenzgarage” . About the top and the hydraulics. First I would always run the car while running the roof hydraulics.. low battery voltage will take out the main control board… second I would change the hydraulic fluid in the trunk under the spare tire. There is a pretty easy method .. I am sure it is posted but if you need just ask and when I have time I will post it for you .
Ok good luck and they are great cars and you have a very good year 98 with the updated harness.
“thebenzgarage” . About the top and the hydraulics. First I would always run the car while running the roof hydraulics.. low battery voltage will take out the main control board… second I would change the hydraulic fluid in the trunk under the spare tire. There is a pretty easy method .. I am sure it is posted but if you need just ask and when I have time I will post it for you .
Ok good luck and they are great cars and you have a very good year 98 with the updated harness.
Thread Starter
Newbie
Joined: Feb 2009
Posts: 4
Likes: 1
From: Glasgow
SL320
Congrats on buying a great car. Wanted to let you know my son has a large R129 parts store on ebay
“thebenzgarage” . About the top and the hydraulics. First I would always run the car while running the roof hydraulics.. low battery voltage will take out the main control board… second I would change the hydraulic fluid in the trunk under the spare tire. There is a pretty easy method .. I am sure it is posted but if you need just ask and when I have time I will post it for you .
Ok good luck and they are great cars and you have a very good year 98 with the updated harness.
“thebenzgarage” . About the top and the hydraulics. First I would always run the car while running the roof hydraulics.. low battery voltage will take out the main control board… second I would change the hydraulic fluid in the trunk under the spare tire. There is a pretty easy method .. I am sure it is posted but if you need just ask and when I have time I will post it for you .
Ok good luck and they are great cars and you have a very good year 98 with the updated harness.
Super Member
Joined: Jul 2016
Posts: 704
Likes: 129
From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
hydraulic fluid change
I always suck out the old fluid with a turkey baster style fluid remover.. fill with new fluid than take off the return line and start to run the system … keep filling the system with new fluid until you see clean fluid come out of the return line… put the return line back on and make sure your fluid level is good
Thread Starter
Newbie
Joined: Feb 2009
Posts: 4
Likes: 1
From: Glasgow
SL320
Hard top issues
Congrats on buying a great car. Wanted to let you know my son has a large R129 parts store on ebay
“thebenzgarage” . About the top and the hydraulics. First I would always run the car while running the roof hydraulics.. low battery voltage will take out the main control board… second I would change the hydraulic fluid in the trunk under the spare tire. There is a pretty easy method .. I am sure it is posted but if you need just ask and when I have time I will post it for you .
Ok good luck and they are great cars and you have a very good year 98 with the updated harness.
“thebenzgarage” . About the top and the hydraulics. First I would always run the car while running the roof hydraulics.. low battery voltage will take out the main control board… second I would change the hydraulic fluid in the trunk under the spare tire. There is a pretty easy method .. I am sure it is posted but if you need just ask and when I have time I will post it for you .
Ok good luck and they are great cars and you have a very good year 98 with the updated harness.
One other thing, my hard top sits a bit high on the nearside of the car, about 10mm (gap) higher on one side than the other. This is where the b post meets the body. There is a small pointed locating pin on the hard top exactly where it is high. It also means that the top door/window strip doesn't align with the same strip at the bottom of the hard top. Any idea what could be the issue?
I've checked the hole the pin goes in and it's clear and greased, seem to remember I read there's shims that can be adjusted there but not sure if that was on the 129 roof or another car.
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Super Member
Joined: Jul 2016
Posts: 704
Likes: 129
From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
changing fluid
you will have the spare tire out and trunk lid open… yes operate the system ALWAYS keep adding fresh fluid and watching the return line to see when the dirty fluid turns clean.
Make sure all the channels and seals are cleared
Make sure all the channels and seals are cleared
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