Well I just bought a 1997 C280 and I was thinking since it was newer than my w126 and w123 that there’d be better parts availability. I think I’m very wrong.

Today I tore my driver’s side door apart to check on a vacuum leak in the door lock. The leak was getting really bad and I could hear the pump overrunning and the hissing sound in my door. I figured okay, it’s just a vacuum lock actuator.

Well the actuator is integrated with the door lock mechanism. It is discontinued according to Pelican and other sites. The car has the optical remotes which go through the door lock mechanism which makes it inconvenient to open without remotes. There’s no keyhole on the driver side. This also means the locks are special setup for the optical remotes and they aren’t common. The 1999 and up uses a slightly different lock and it seems to lack a switch that tells the security system the state of the locks.

I capped off the vacuum line and I’m going in through the back door. Maybe I’m looking at key tumblers? But I’m not sure those will even work with my lock mechanism. I guess I can go to the JY and cannibalize an entire set of door handles and locks.

I guess I’ll call Pelican and ask what to do. It looks like this car is going to slowly become junk as I cannot replace parts. Rebuilding the door lock looks hard because it’s riveted together. Also getting a diaphragm may be difficult.

How are you guys dealing with NLA? I’d go to the junkyard but I don’t want rotten old diaphragms. BTDT and they die in short order.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles

Chances are that the vacuum passage at the bottom of the lock is where your leak is. It is a tube molded into the plastic housing and is sealed on one end by a steel ball. Cracks form around the ball. I solved the problem by encasing the entire lower lock in epoxy.

Hey Vince, OMG I should have asked here first. About 90% of my leak is in a crack on that fitting. I totally missed it. About 10% looks like a leak in the diaphragm.

I’ve coated the whole thing with epoxy.

It is really hard working on this door. To get the lock out I had to remove the glass. I had to drill out some rivets on the regulator rail too. There is no room in there. I had some hopes that I could get an electric door popper in there or a small vacuum motor off another Mercedes. But there really isn’t much space to put anything else in the door.

I hope the epoxy works. It looks promising. I need to sit on my hands till it fully cures. Not looking forward to putting the window back in.

If it all works out I’ll look into epoxying the passenger side too. I can hear a hiss from that one too even with my driver side plugged off.

Thanks for the tip.

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles

Okay so I got it all together. The epoxy didn’t work. The leak in the diaphragm was pretty bad.

It took me many hours to fix this thing. Taking the lock out is a chore…the window glass must come out. The vertical guide rail of the regulator has to be deriveted and pulled out to make space. The anti theft (slim Jim) guard is a bear to get in and out without messing up the mousetrap spring on the door handle. I finally figured out how to block my handle outward with a tool so it would keep tension on the spring to keep in place.

There is no room in that door to work. I finally found the one place I could jam a vacuum lock motor off my w126. I zip tied it in the door and fastened a welding rod to activate the door button. Things were complicated by the fact that the w126 lock motor has 2x the throw necessary to pull and push the w202 button. I had to leave some slop in my mechanism to compensate for this difference. Basically my motor had to take up some slack before it engages the 202 linkage so it can move more while the 202 parts move half as much. Took me forever to figure this out and set it up. Otherwise the swap is unreliable because it throws the mechanism too far.

Anyway here is what I got. That’s the 126 lock motor fastened to the lock button rod with a piece of welding rod. I later found the two nuts need some space between them to compensate for the longer throw of 126 motor.





That’s a 126 lock actuator back there. It’s secured with two zip ties.




While I was doing this I also solved this annoying beep sound under the dash. I thought it was electronic. But it was the squeal of a punctured diaphragm for the footwell flaps. Like a kid playing with a balloon to make a squeal. Took awhile to find it but I basically took the kick panels off the car and started listening. Once I was sure it was on the pod I disconnected it and it stopped.

I plugged off the circuit. And of course the pod is NLA.





Apart from this stuff the car was in pretty good shape. I got it for $2000. Runs well. Passes smog. It had a nasty vibration in the steering wheel from 40-50mph. It needed an alignment. I set the toe with my Fast Trax and the vibes stopped. The car is really shaping up. I think the m104/722.6 combo is pretty good. Looking forward to learning about this car.

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles