Door Latch Failure with the NEW recall style latches

[tolsen 630]

There are at least 3 different versions of the lock. Mine has same pressure casting as the old one in stickman's photo but also a black plastic piece at top forward of lock case.

As far as I can tell all they have done with the later versions is to cut down on parts. Obviously, with fewer parts there is less chance something will go wrong unless the part that was removed was essential for the functioning of the mechanism.

[Francesco 71]

Yeah, I followed along in the old thread and just like BigRick, after a night of soaking I took it out into bright daylight, blew it out with compressed air, and saw the little post in the pressed case. It still didn't move on its own but after working it loose and more working it in a mineral spirits bath it came free. Once I was satisfied it no longer hung up at all I dried it out and liberally sprayed every friction surface with HHS2000 and allowed the carrier to evaporate before cleaning the outside of he bracket and reinstalling. Works better than new now.

Just like Duck, the most exasperating part of the whole exercise was getting the plastic rivet out of the triangle to partially remove the nose cone. Other than that, removing and reinstalling the handle, mirror, latch and door panel was a piece of cake. Not something one wants to do as "routine maintenance" -- in other words, really bad latch design -- but now I know it's not that tough.

[Francesco 71]

Noticed on the drive home that the door-ajar light is on, though the dome and console lamps turn off normally. I would've thought the one microswitch is used for both systems, but I guess not.

Any idea what it might be? HHS in the microswitch?

[tolsen 630]

I think lock actuator has no position feedback and there is only one micro switch per door. Did you soak lock case complete with micro switch and actuator?

[darren 192]

I would raise the issue with Transport Canada again. Since this is a follow-up on a previous recall order, I wonder if an investigation might be expedited. If Mercedes-Benz replaced the latches but didn't actually fix the underlying problem (a poorly-designed mechanism), TC won't be impressed.

I actually had the passenger door of my 450 fly open while driving. (I was making a left turn from Lakeshore onto Parkside Drive in Toronto.) major safety issue there, and "not using the door" seems irrelevant. The latches can let go at any time, it seems, not just when engaging or disengaging.

Edited May 7, 2016 by darren

[Francesco 71]

Only bathed the latch in mineral spirits, but may have gotten the creeping spray grease in the micro switch afterwards. No soaking or greasing of the lock actuator.

[tolsen 630]

My new left side lock case arrived this morning. Turns out to be the later version. Much easier to break into as far as I can tell compared to those on my 450. Mechanism is conventional and rather simple. Have been looking at its internal workings for several minutes and struggle to see any trace of grease. I bet that is why they fail.

if anyone needs a left side lock case, please contact me by private messaging. Asking price is £27 plus postage at cost.

[CANMAN 23]

The drivers door on my wife's smart with the new style door latches were acting up, the inner handle wouldn't stay flush with the trim protruding about 1/2 inch and the door not latching sometimes.

So I took it apart today.

The mechanism is different from the previous version but still has the same problems as the old one.

It can't tolerate any grit inside.

I bathed it in varsol and operated the mechanism while submerged ( microswitch and wires not in varsol ).

Photo 1 show how much grit was left after pouring the varsol back into a container.

I blew it dry with compressed air and lubricated everything inside and out.

Photo 2 shows where the latch is that holds the mechanism shut, the tip of the screwdriver is pointing to it.

The preview photo is with the mechanism on it's side, but when you open the photo the mechanism is upside down, the latch is at the top of the lock

The door latches good as new, hope to get another 2 years before having to do it again.

Now I have to do the passengers door and both doors on the other car as a preventative measure.

Canman

Edited August 9, 2016 by CANMAN

[tolsen 630]

I got it now. Canadian grit and dust is the problem. Must be much less of it blowing about here in Scotland due to endless rain. That explains why my door latches still are in a perfect condition.

[lebikerboy 96]

Some places in Canada might have the grit and dust problem but

not here on the Wet Coast. I've never had any problems with my latches

whatsoever but keep regularly lubed with Wurth HHS 2000...

I still have the recall letter from M/B just in case though!

[smartzuuk 167]

All I can think is somehow some latches are getting winter salt/sand/related grime, and others, like Vancouver cars, are not.... I've still got the originals in the canada1 at 99962 kms....

[kdubya 34]

I have the new latches, and my drivers door sticks open nearly everyday. I'll have to take mine off and clean/lube it. Does anyone know if they will warranty the new ones? Mine are nearly 2 years old.

[CANMAN 23]

I think the warranty is only 1 year, but check with Mercedes, I may be wrong.

Despite the removal and cleaning I did, my drivers door latch has been sticking again.

Until it is warm enough to do the work of replacing it, I have been carrying an extension cord and heat gun in the back of the car.

If you don't have a heat gun a good hairdryer will probably work, just take longer.

You have to blow the warm air into the lock mechanism for a minute or more and work the latch back and forth with a screwdriver to free it.

Obviously the problem is moisture freezing in the latch, it doesn't hurt to spray some moisture dispersing penetrating oil like WD40 into the latch after it is warmed up.

Damn thing failed 3 times the other day, had to use the heat gun each time until I got home and sprayed it again.

canman

[tolsen 630]

I would not use wd40 since it is stinks, is far too thin and evaporates in no time.  A sticky grease like chain lube is better. Thin and penetrating when applied and won't come off because it sticks to anything.

[LooseLugNuts 557]

if youre sure its freezing moisture just splash some engine coolant on it every few weeks

[tolsen 630]

Wetting in glycol will increase friction between moving parts so not very smart in my humble opinion. 

[LooseLugNuts 557]

i never would have expected that...glycol on my hands tends to turn my wrenches into squirming eels

[tolsen 630]

Feel free to try out glycol on the locks but not on my Smart.

[LooseLugNuts 557]

ive not had lock mechanism problems yet...but i have injected glycol into the small door handle pull cables with no problems after having them freeze up on early wet cold winter days...i do the same to my snowblower cables ...it stops the chute control cables from freezing up

 

same with my brake pedal switch...hasnt ever froze up since it started occasionally placing small amount of glycol on brake arm 

[tolsen 630]

I suppose too much grease is also no good.  The wrong grease can go solid like butter in the cold.  Best to test in freezer before applying.

[Willys 747]

I think what is being suggested is to use glycol to help stop freezing.....no?   Bike chain lube heated is what I would be going after after slightly cooking cables to get all moisture out of them.   To each their own.....whatever works for you I guess...?