Automatic Trunk opening? - PeachParts Mercedes-Benz Forum

tecqboy · #1 03-28-2003, 12:01 PM

Hi Guys: From time to time, when I go out to the garage, I find the trunk lid on my 91 SL300 has released; just enough to be noticable. I haven't done anything to release it. If this happens and I don't notice it for several days with the car parked, the trunk lamp will drain down the battery. I know it's vacuum operated, but the vacuum has not bleed off the rest of the system. The doors and other vaccuum stuff are still OK. Is there a check valve someplace I can look for? Tod

jjrodger · #2 03-29-2003, 03:19 PM

Yoiu can turn off the boot light using a key operated switch located just within the boot, adjacent to the latch, on the inside of the sill.

elau · #3 03-29-2003, 11:08 PM

I am not aware that the trunk can be opened automatically or remotely. At least not the earlier model. I always wonder why such an expensive car does not come with that feature. At the least trunk release from the inside. My cheap old Honda had such feature. Or is it some secret I don't know about?

dmorrison · #4 03-29-2003, 11:20 PM

I'm not familiar with the 129 SL. But it sounds like the trunk lock tightening vacume is bleeding down and allowing the trunk to open slightly. The vacume system may have a check valve in it to prevent it from causing a leak in the entire system.
Now don't hold me to this. To my knowledge the 90's Mercedes had the locking system that you latched it and then the vacume system pulled the trunk/door tight. If you 129 does not have this the completely disreguard this post. If it does than your trunk diaphram is leaking down adn allowing it to release the trunk.
You need to isolate the trunk unit and check it with a vacume unit.

Dave

jjrodger · #5 03-30-2003, 02:53 AM

My R129 does NOT have a boot lock that pulls itself closed (as on the W124 estate and W140 saloons). Try posting this in the Tech Help forum, I think you'll get a good answer pretty quickly.

tecqboy · #6 03-31-2003, 08:06 PM

Thanks for your input. My 1991 129 has the IR key/remote. You have to close the trunk lid by hand and you have to open it ( read that release) by pressing inward on the key lock/button. The IR remote only activates the vacuum locks. That's why I'm so puzzled. Pressing the IR remote isn't supposed to open the trunk, just allow the trunk to open when you to push in on the "lock". A vacuum bleed down problem for sure, but I don't recognise a check valve on the "diagram" in the parts breakdown book I got with the vehicle. To add to the problem, it's intermittent. The weather is warming up a bit here, so I suppose it's time to disassemble the mechanism and have a look see. Thanks again. Tod

Peter Guenther · #7 04-01-2003, 08:45 AM

I dont have a 129 but a lot of the issues apply to the 140 body. The pulldown is controlled by a vacum punp which causes the latch to retract untill it catchesa step in the locking mechanisim a few seconds later the vacum is released. Maybe the pull down is not far enugh to let the catch "catch"!. There was a post somewhere that caimed the pull in should be a little father, and then relax. If you manually close the latch the retractor should pull in and you should be able to notice the latching action, and then hear the vacum release. MB checked mine by applying vacum with a hand tool and then observing the bleed down. It turned out to be a bad pump very common on the 140. The later cars had a trunk release if you held the unlock button, but that would completely open the lid. I hope this helps.