Smart 451 Clutch Actuator DIY Service

[@christopherl.miller4092]

Thanks so much for making these videos. This particular one was perfect for what I needed to do. It actually gave me the courage to do it on my own. The most I have ever done before is change the air filters and the spark plugs lol. The job went without a hitch, and the car pulls away from a stop and shifts through the gears much more smoothly now.

[@PBGarage]

Glad it was helpful! Stay tuned for more to come.

[@raymondmcdonald7085]

Thanks for the info. When I was looking for a smart to buy, one that I test drove had shifting issues. At the time I didn't know what was wrong but I knew something wasn't right. The owner tried to convince me the shifting was normal. I passed on the purchase of that one and purchased another that shifted normal. I have worked on most everything I have ever owned and I must say these smarts are engineered a little different. Good to know!

[@PBGarage]

Yeah they take some getting used to but once you have the right tools and a bit of practice they aren’t so bad. Always have to remember it’s a whole car worth of stuff rammed into a half a car so it’s bound to be challenging lol

[@geidsonqueiroz2680]

hello friend I have a smart 451 mhd I have a clutch problem. I can't start the car it won't start I have a total of 04 DTC faults. can you help me thanks in advance

[@victoradorno6047]

Yo estoy pensando en comprarme uno,pero veo vídeos para familiarizarme con la mecánica de este auto que me gusta mucho. Aprendo mucho con tus vídeos ,gracias por tomar tiempo para hacerlos . Saludos desde la isla de Puerto Rico .

[@christopherl.miller4092]

Este vídeo me ayudó mucho. Me dio el valor para hacer este trabajo. Funcionó mucho mejor después de hacerlo. Saludos desde Nueva Jersey, los estados unidos.

[@PBGarage]

Thanks for watching! We really appreciate it, hope that all the info helped you pick a good one to buy!

[@PBGarage]

Glad our video was helpful to get the job done!

[@jixxen]

Thank you for the video! Our smart is often not shifting into reverse or drive; I’ll try this fix over the weekend.

[@PBGarage]

Worth a try for sure!

[@jixxen]

@@PBGarage Well, still having intermittent problems shifting into reverse, but at least I know my actuator is good and greased now!

[@ribbitism]

@@jixxen smart did recognise this problem and put out an ecu update because some of these wouldn't push with enough force to get it into reverse, the update made it have just a little bit more force to engage. try moving the car forward a little by foot or with first gear and then try reverse (basically to reposition the gear so it slides in easier). if you find this regularly works, you probably need the updated software. you might have to pay for it now, if it never got it when they were offering.

[@Mason-nm1vf]

Thought I'd drop in a comment here about the whole process and what I experienced because I just got through doing it on my 2014 Smart that has 91,514 miles on it. My car had been surging a little bit when in drive, and when I put it in reverse, that's where the really big problem was, it was chattering and jerking. When I began investigating what it could be and ran across these type videos I thought, for sure I had found the fix. It turned out it WAS the fix! My car now runs and operates like it did when it was new. Couple of things to point out for everyone. When you are setting up the "lash", the amount of "pressure" on the clutch level itself, all I did was feel for the actuator rod to touch up against the clutch lever. Now I moved back and forth about six or seven times till I made sure I was feeling it correctly. From that point I put a little bit of pressure on the actuator itself, and I was very careful, as I slid it towards the bellhousing three more indicator lines. So everyone clearly understands. There are indicator lines, kind of like quarter round lines. The type you're seeing in these videos that are molded into the housing of the actuator. When I touch the clutch lever there were three lines showing. Then I pushed it three more. That's what the manual calls for you to do. It's easy to find this one line. The Other important thing I wanted to share with everybody is I did not have the software nor a laptop to plug into the car. The more I read about doing this job.I learn that you do not have to do that. Once you're finished with the job and you're about to drive the car to test your work. Just turn the car on and let it idle for about thirty seconds to a minute and a half. The car will learn the actuator position on its own. At least that's what I experienced. And then what I did is, I shifted the car somewhat slowly from park to reverse, to drive, to neutral, to reverse, to drive the neutral, and I repeated that maybe ten times slowly while my foot was on the brake. Then I dropped it in drive And went twenty or thirty feet stopped it, put it in reverse, did the same thing forwards and backwards, about six to eight times. At this point I knew immediately that the car was in tremendously better shape than it had been for the last eight ten thousand miles. My biggest problem is that when I was in reverse backing up, the car would shake and chatter very hard. Almost surging at times. That was all gone immediately. Then I took it for a shakedown run. As i've already mentioned, it ran, just like it was brand new. Hope this info helps some of you out there.

[@Smartsparky]

Can’t believe I’m about to tackle this myself. Wish me luck!

[@PBGarage]

Mark the position!

[@lordzevallos]

Do you need the teach in program if you’re just greasing/cleaning the clutch actuator or only if you replace it ?

[@PBGarage]

If you mark it really well when you remove it, and you reinstall it in exactly the same spot you don’t need the tool necessarily.

[@Mason-nm1vf]

If you don't have a laptop/software and can't have the car "learn" what you did, what do you do? There are others on here tutoring us with similar procedures, but are not talking about having to deal with plugging into a laptop. Any advice would be great appreciated.

[@PBGarage]

The main thing is to mark the position of the actuator before you loosen the bolts off so you can reinstall it in the same position. Beyond that you can make a certain amount of adjustment by moving the actuator closer to or further from the flywheel. I’ve managed to adjust some this way but it’s really not ideal and takes a lot of trial and error and very tiny adjustments. Any garage that has a Mercedes factory scan tool should be able to perform the adaptation so unless you’re somewhere really back woods, there should be an option to do it “right”.

[@danyalhussain9525]

Hi I wanted to replace with a brand new on will I have to reprogram or can it just work plug and play if it is in the correct position

[@PBGarage]

It might be difficult to get it to activate properly if replacing with a new one. You can adjust it somewhat by hand. If the clutch engages too harshly move the actuator closer to the flywheel and if it slips or doesn’t engage move it away from the flywheel. But it can be very difficult to adjust it properly that way if you aren’t experienced mechanically as it must be adjusted in very small increments and you must be very confident in your ability to feel how it is engaging.

[@danyalhussain9525]

@@PBGarage never mind I’ll leave it at the garage this seems a bit complicated, my car just stalls completely when in gear and got told it’s a simple fix of replacing the actuator but it sounds a bit complicated. Thanks for the response

[@minitrucker68]

Found the issue with my coolant leak on my Fortwo but I have no idea what this part is called that I’m looking at.. it’s the assembly that was next to the thermostat.. has an in and out and a small fitting off the side that goes to a hard line and connects close to the thermo sensor.. well that fitting is broke clean off and someone before me used about a tube of silicone to stop the leak long enough for me to find it lol

[@PBGarage]

That’s a bummer that they sold it to you broken. Do you mean the flat plastic housing that bolts to the head? With the one big pipe and the one little pipe?

[@minitrucker68]

Hey yeah now that I have the motor down “in service mode” I see a lot of questionable things.. there’s probably a tube of orange RTV on miscellaneous things here and there. That being said I found the part I was looking for. The water outlet pipe. And it’s the small fitting that was broke completely off and they Jimmy rigged it enough to pass safety. While the engine is down I may as well swap out the reluctor rings for the abs as I had an abs light come on on the way home from picking it up from the shady dealership downtown in Ottawa 😒

[@bertlzansinger]

Many thanks for this informative video. I miss, in which position the car was set (N, R, 1) prior the exchange and if the battery was disconnected prior removal, though. Any hints on that? [I do not have a tool for relearning the clutch or delete error codes] Cheers

[@PBGarage]

Hello. In North America the cars have P, but for rest of world you’ll want to leave it in N and disconnect the battery.

[@bertlzansinger]

cheers mate! @@PBGarage

[@AdrianA4M]

I wonder if one couldn't use a 'trans oil' instead of grease? Measure the volume inside and then add maybe 50% of the volume in oil? Your thoughts guys?

[@PBGarage]

The problem with any kind of trans oil is that I think it will melt/soften the rubber boot or the various gears/seals etc in the actuator. If you had a silicon based lube of some kind that was non reactive maybe? Not sure.

[@yamahar1sho]

Your video has been very helpful on this, my only question is how exactly did you get the actuator fully retracted? I tried plugging the connectors together and turning the key into the on position (didn’t start the ignition), tried switching gears and nothing happened. Using the paddles when shifting to the second gear, there was a clicking sound, but still no movement. The way it is extended right now, it isn’t possible to bolt it back to the vehicle. Any help on this would be greatly appreciated!!

[@PBGarage]

I’ve been able to get it to retract by just turning the key on and off with the actuator plugged in. If it won’t retract it could be an issue with the actuator. If you have STAR/DAS you can also force the actuator to the open or close position from within the software, but again it might not work if the actuator is totally dead.

[@yamahar1sho]

@@PBGarage We have tried turning the key on and off, maybe it’s toast. Thanks for your quick response on this.

[@gplusgplus2286]

Is it really necessary to do the adaptation? I just bought a new clutch, mine is done and will service the actuator but I don't have the software. Service manual says to install the actuator 3 lines in from the point it barely touches.

[@PBGarage]

I’ve managed to do it just by feel or trial and error driving the car. But it’s tricky.

[@neftaliortiz8877]

Hi I just put the new clutch actuator on my smart car,,connect and everything and the car not run is like in parking all the time not neutral or nothing when I change gears the actuator not move or nothing what the solution after a brand new clutch actuator?

[@PBGarage]

First thing to do would be to check your wiring to see that it hasn’t rubbed against the transmission and worn through

[@jeffsmystic]

Where can I get a new actuator?

[@PBGarage]

Mercedes/smart dealer network. There are also online sources.

[@elwynrowlands9486]

Does anyone know if it’s ok to take an old actuator off and replace it with a new actuator in the same position as the old one without the software / re-teach stages? Will it be ok simply by fitting the new actuator in the same location as the old one? I have sockets and spanners but no software / clever technology.

[@PBGarage]

It’s tough to know for sure. But you can shimmy the actuator in/out to get it dialed depending on how it’s driving. It takes some fiddling but I’ve done it without the software.

[@BB..........]

Where do you find that software?

[@PBGarage]

I bought the multiplexer and software on AliExpress. Just search MB Star you should get some hits. Mine is a C3 but I think there’s other options available now.

[@MiloFarms]

@@PBGarage Do you have a link or any more information on what MB Star program and equipment I would need for a 2015 Smart?

[@leewilhelm6700]

What kind of grease did you use?

[@PBGarage]

I used Bel Ray Waterproof Grease. But any dielectric or silicone based grease will work well. I didn’t want to use anything that could attack the plastics like regular wheel bearing grease or the like.

[@toddstuck72]

Do u have an email or website

[@PBGarage]

[e-mail]

[@petarpiljak9552]

You couldn't solve the clutch problem this way. It would be great if the problems were solved with a little lubrication. Your clutch is worn out and the actuator does not have enough power to push it to the end position. You cannot do the learning procedure if the actuator does not disengage the clutch completely.

[@PBGarage]

You’re talking about 2 different issues. Clutch actuator binding is common and easily solved with cleaning/lubrication. When the actuator hits a limit on current flow it will cause the 3 bars of death and/or poor shifting. I’ve brought many many 450s and 451s back from the dead with just this service. Beyond that, there are other issues with the clutch that we are going to look at in future videos but this is the best first stop towards resolving clutch/gearbox issues.

[@Ritarvt]

My 2009 (146,000 miles) started misbehaving late November. It would stall and be very jumpy at times. I never got the 3 bars or any other engine lights. But I did get a code for the clutch actuator. Upon finding your video for how to take it off, clean and lubricate it, I just finished this! Slightly delayed because I had knee surgery! But I was able to do this service as you instructed (marked the bolts, etc) and test drove today! It shifted extremely smooth! I’m hoping that this lasts another many miles as I love this car!! And as for as the other ladies who don’t think they can do it, you can!! Thank you for this great tutorial!!

[@PBGarage]

@Ritarvt I’m so glad to hear it! It’s an easy DIY as long as everything gets marked off and put back the same way. Glad to hear your car feels way better!

[@Ritarvt]

I am very grateful for your video! Made things super easy!

[@cftpm678]

En français s’il vous plaît, 👀🧐🇨🇦

[@PBGarage]

S’agit d’ouvrir la caisse de l’actuateur, nettoyer, lubrifier avec un produit à base de silicone, et réinstaller sur les mêmes marques. C’est à dire, sans changer la position de l’actuateur relatif à la transmission. Si possible, utiliser le programme STAR par Mercedes pour effectuer une adaptation numérique.

[@cftpm678]

@@PBGarage , merci 🇨🇦

[@lesprudence374]

Hi just a question why remove from car if plastic cover just comes off with just 6 screws which can be done in situation never made sense to me? Or am I missing something. Love video's keep them coming. Thanks

[@PBGarage]

Glad the vids are helpful! I haven’t tried to remove the cover in place, but I think it would be really tough to do with it installed on the car since the heads of those 6 screws face up towards the engine/trans, so getting access would be very difficult compared to the relatively small effort of removing the 3 bolts and one electrical connector. It’s good to tackle those bolts at your leisure when the car is running properly so that when the actuator does fail, they come out easily as well and you’re not breaking them late on a Sunday night in a blizzard when you have to get to work the next morning.

[@MrMr123]

That car has 216,000 MILES on it.... wtf.... wow

[@PBGarage]

216k km, not miles, if I said miles in the video that’s a mistake lol. That being said I’ve seen plenty of 451s over 200k miles, they’ll do the mileage if they’re looked after.

[@bquattrog]

Good video. Those mounting bolts didn't look like they wanted to go!

[@PBGarage]

No they didn’t! Really made me work for it to not snap them or round the heads.

[@JimothyPP]

I've got a nice "crunch" noise almost every time I shift into reverse. I'm hoping doing this will solve my issue... However I don't have access to the DAS system so I'm hoping the car can sort of "re-learn" itself.

[@PBGarage]

Just make very sure that you mark the position of the actuator before you take it off and make sure you put it back on in the same spot and you should be fine.

[@elwynrowlands9486]

What if you take an old actuator off and replace it with a new actuator in the same position as the old one? Will that also be ok without the software / re-teach stages?@@PBGarage

[@Windtee]

@@elwynrowlands9486 I replaced my old actuator with a new Sachs made in Germany and positioned it in the exact spot the old one was in. No relearning software used.

[@rapunzeleh546]

okay, should have watched this before... took the thing out, mine has rivets so can't take it apart and grease it. so slip the boot off and grease inside. put it back in, now it make a banging noise. didn't know it had to be relearned.... obviously i don'[t have smart software to do that, anyways around that?

[@PBGarage]

If you have it reinstalled in the same position as when you took it out you should be ok. Even if you were way off it still shouldn’t make a banging noise. Sounds like the clutch release fork may be worn through or you have some other issue with the clutch pack. You could try moving the position of the actuator forward or back and try again to see if you can get close to a proper alignment, if the clutch engages too harshly move the actuator towards the flywheel. If the clutch slips too much and the car doesn’t move, slide the actuator away from the flywheel. You may have bigger issues.

[@rapunzeleh546]

@@PBGarage well before i 'touched it' there weren't any noises. could i have reversed the connector? i know 1 and 6 are the power in... i don't have a wiring diagram to see what colours coming in should correspond to those. so two things i'll try once this rain stops. loosen the screws and lets it go were it needs to go. (thinking about it, wondering if it pivotted - i did check the position of the first screw, the one that is easiest to get. but the one behind i didn't... will also try to flip the connector.

[@PBGarage]

@rapunzeleh546 the connector should only go one way.

[@rapunzeleh546]

@@PBGarage the plastic was really brittle and the tabs broke off... can it still only go in one way?

[@PBGarage]

@rapunzeleh546 no idea

[@Windtee]

I did the rebuild and experienced marginal actuator improvement, but not enough to stop the hard slamming into reverse. Was curious to see what my local MB Smart service would find. They hoped to find $2,400.00 in my wallet... in order to replace the unit as a starting point for diagnosis. In other words, they weren't completely positive if the actuator was faulty. Crazy! Unfortunately, I still had to pay for the expensive diagnostic walk-around by the "smart technician." I'm considering buying a new OEM Sachs and installing myself. Out of curiosity, could the clutch-actuator's electric motor be a contributing issue to the slamming?

[@PBGarage]

The actuator clean and lube here helps a ton in most cases, when you had it in did they re-teach the clutch engagement point? I do think there comes a point where the issue starts to be in the clutch pack itself and no longer with the actuator.

[@Windtee]

​@@PBGarage I don't know if Mercedes-Benz attempted a re-teach, but here is a direct quote from my recent service-receipt given to me yesterday when I picked up my smart. "Customer states they took apart the clutch actuator and now there is a hard shift to reverse followed by a clunking noise, shifter is hard to go into park and jerks going into drive. CDCE perform diagnostic scan, retrieving engine fault codes related to the CEL. Road test to verify complaint. Preliminary evaluation provides technician path to cause of failure." "Multiple codes indicating clutch actuator fault, performed actuation test of clutch motor via SDS and actuator repeatedly failed test. Visible damage to boot at actuator, will require starting with replacement of clutch actuator. Customer declined repairs." "Check Engine light is on." I hope it's not the clutch-assembly. Been there, done that on a 1983 Mazda years ago. BTW, subscribed. Thanks for your vids.

[@JosephParagas-j6r]

I had a similar issue and it turn out to be broken clutch pressure plate. Save yourself the trouble and the expense, replace the clutch yourself. This all seems to affect 451 models from 2012 onward the SACH pressure plate were manufactured in China.@@Windtee

[@PBGarage]

It’s definitely seeming like the “3 bars of death” failures are most often related to the clutch actuator, whereas if the actuator is in good condition, adjusted, and the car’s still shifting poorly, then it’s more often an issue with the actual clutch pack.

[@Windtee]

@@PBGarage @user-xf2fo1cs1q I bought a new Sachs actuator and will install this week. I'll get back with updates after testing.

[@MathieuTechMoto]

Thank you !

[@PBGarage]

Happy to help!

[@jeffsmystic]

Which grease did you use?

[@PBGarage]

Bel Ray waterproof grease.

[@anthonymoore8480]

Great info!!! 🙌 😇

[@PBGarage]

Thanks for watching! Glad to help!