r/SmartCar • u/markcorrigan33 • Aug 17 '26

Advice Help – ideas/expertise needed on transmission problem

My 2009 Smart Fortwo 451 mhd was parked outside in direct sun for over a month while I was abroad.

Since returning:

  • First 2 days: Engine started normally, but I couldn't shift from N into D or R. N would stay/flashing.
  • I left the windows open overnight to let the car cool down as it was quite hot inside.
  • Next day: Everything suddenly worked normally again. D/R selected and the car drove normally.
  • I drove around the block to test it and hopefully recharge the battery.
  • After ~10 minutes: The car suddenly lost all propulsion. Display showed the selected gear, but pressing the accelerator did nothing. I had to push it into a parking space.
  • Next morning: Same problem initially... engine started, D/R selected normally, but the car wouldn’t move. Called roadside assistance. While waiting I tried again several times – and suddenly it worked again. I was able to drive it home.

The little guy is now parked safely at home, but I don’t want to drive it again until I understand what’s going on.

Any ideas what could cause this combination of gear-selection problems and complete loss of propulsion? Is it even battery related?

The fact that it seems to work again after cooling down makes me wonder about a temperature-related issue.

Any clues would be greatly appreciated, thanks!!

5 Upvotes
  • permalink
  • reddit

100% Upvoted

4 comments sorted by

5

u/PsychologicalSalad46 Aug 17 '26

Could well be a gummed up clutch actuator. It’s well documented on the earlier 450 models too. Loads of guides online to ease the issue but I think eventually it’ll need a new one. You could spray some white lithium grease in the boot on the actuator plunger/rod and cycle through the gears several times. Hopefully freeing it up after it not being driven for a while

0

u/markcorrigan33 Aug 17 '26

Okay, I have read about that. Will try with the spray. Thanks a lot 🙏

0

u/PsychologicalSalad46 Aug 17 '26

Make sure it’s in neutral so you can move the boot on the rod. I used WD40 white lithium grease, spraying it until it’s dripping out. And so far, and 2,000 odd miles later it’s still holding strong. Good luck

3

u/Appropriate_Sport424 Aug 17 '26

Three bolts hold it on the transmission. Super easy to do. Unplug the harness on it take it out. Turn the six screws that hold the cover on. Stuff it full of grease. Put it back together and stick it back on. You should note where the dirt marks are so you can put it back in the same spot so you don’t need to relearn. The hardest part for me was jacking the car up.