tat, tat, tat sound

[Docthrock]

Originally Posted by sato7

just wondering what your oil levels are, it might be low! and thus not lubricate the engine continuously. Just a oddball theory but worth a look..

Yep, worth a look for sure. Oil is perfect level, and only slightly discolored after 1K miles.

Waiting for Max to talk to the service guys. Maybe I'll hear something by the end of the day.

As someone mentioned, it might be some kind of a vacuum or suction pump, but man, it sounds loud (comparatively). Maybe tat tat tat isn't quite right, puck puck puck puck..... might b better. I gassed the throttle after the car warmed up, and it started popping (pucking) pretty loudly, quieted down (never slowed down), and didn't stop until I shut off the car. Hmmmmmm......

[chieftmc]

Keep us posted Doc!

[FWOIII]

It's the fuel purge valve......normal...don't worry about it.

[yannou]

mine have same knocking sound, sometime completely go away, but not by releasing the brake, still at 500 miles. at 30 miles got a warning engine malfuction an dealer told me it's octane problem from the gaz they filled up with. any suggestion guys ? hate going back to dealer again.

[smark]

Mine has 1500 miles on its, make the same ta ta ta noise. Louder on the inside of car. Comes, and goes. Smart service in Kansas City couldn't find the issues. Just live with it. It's a Smart thing. It's not a Lexus!!!!!!!

[SuperGeek]

Mine's had the same sound since day one. I think it's a normal function. It gets more noticeable when I come to a stop after driving a mile, engine warmed up. Sort of a puck-puck sound which increases in frequency over time as though it's a valve related to emissions because it goes away when the engine's at cruising speed and comes back when it's below optimum range (hot and idling).

If anyone hears different from an official source, definitely let us know.

[PeteInLongBeach]

I believe this has been determined to be the evaporative emissions cannister purge solenoid. It's a duty cycle / frequency valve. The tapping sound at idle is apparently normal in the smart, probably due to its location and/or design.

Nothing to worry about.

[mdfortwoguy]

I've got it, too... I'm used to it though.

I'd say it's normal... perhaps they'll come out with a TSB down the road for it... alas - it's just another quirk of the car.

[Mbenztech]

I didn't read throught the whole thread....... so if someone already said it....here it goes again. To me it sounds like the purge valve. I'm a benz tech......we have plenty of issues on some of our cars for the same noise. I'll be going to Smart school next month.......

[mdfortwoguy]

Has anyone found out if there is a TSB out for this yet? I would like mine to be looked at when it goes in for the 2.0 upgrade here in a week or so - and would like to have that info in hand before I take it in.