tat, tat, tat sound

[eqwalker]

I guess I'm the one that is going to post all the little things I observe and hear about the car, but I like to get others input and see if they are observing the same.

I have noticed when I stop at a stop light, and have my foot on the brake, I hear this light tat-tat-tat-tat sound sometimes from the engine (not the exhaust) that speeds up and sometimes disappears completely while I'm sitting at the light. It almost sounds like something tapping against something but will speed up and sometimes goes away. When you let off the brake it goes away for sure, if it hasn't already while you are sitting. Anyone hear that on theirs? I suppose it has something to do with the transmission? I guess I'm too observant...

[Old smart]

Originally Posted by eqwalker

I guess I'm the one that is going to post all the little things I observe and hear about the car, but I like to get others input and see if they are observing the same.

I have noticed when I stop at a stop light, and have my foot on the brake, I hear this light tat-tat-tat-tat sound sometimes from the engine (not the exhaust) that speeds up and sometimes disappears completely while I'm sitting at the light. It almost sounds like something tapping against something but will speed up and sometimes goes away. When you let off the brake it goes away for sure, if it hasn't already while you are sitting. Anyone hear that on theirs? I suppose it has something to do with the transmission? I guess I'm too observant...

There has been a lot of talk on the smartmaniacs (UK) 451 forum about such things. They haven't figured it out yet.

[randyzimmer]

Originally Posted by eqwalker

...when I stop at a stop light, and have my foot on the brake, I hear this light tat-tat-tat-tat sound sometimes from the engine (not the exhaust) that speeds up and sometimes disappears completely while I'm sitting at the light. It almost sounds like something tapping against something but will speed up and sometimes goes away. When you let off the brake it goes away for sure...

I'd look for an ABS pressure pump.

[SMARTIEPANTS]

same here it seems to do it more when the gas is down to 3 bars, but then it still does it after i fill the tank up for about 50 miles or so then it stops, it seems to tap at about 8 or so times per second,, i even stopped by auto zone and picked up one of those stethscopes things,, it allmost seems louder inside the car than it is outside,, i have had times where it dosen't stop, , even took off the engine cover while it was running ,, seems to be comeing from the top of the engine,,, it dosen't sound like a metal on metal ,, more like a resonince through a plastic intake or something like that,,, i am going to call my smart tech and see what he has to saw,,, got allmost 600 mile on it

[Gortok]

Most likely fuel injectors clicking open and closed.

[jwight]

Don't know where it's located but some electric pumps make a tapping sound occasionally.

[SMARTIEPANTS]

after more driving i am changing my mind about the level in the gas tank having anything to do with , since mine now seems to be doing it most of the time,, you will not notice it if you have the radio on or the heater blower motor running,, awaiting the return call from the smart tech dude

[Old smart]

The 450 parts break-out indicates the electric fuel pump is in the center of the fuel tank top. Yah, I know that you are talking 451, not 450, but if they did it once, they likely did it again. Anyway, the fuel tank (in both) is located under the drivers seat and footwell.

[SMARTIEPANTS]

got this off of the Indy region thread,, the tech said it is an auxillary motor that fires up once in a while for 15 seconds to heat up the O2 sensor,, i am still waiting for the tech to return my call,, always makes me a little nervous when the tech is to busy to return calls

[sato7]

Originally Posted by eqwalker

I hear this light tat-tat-tat-tat sound sometimes from the engine...

I think it is most likely you bought the Indian version.. the TA-TA! thus the sound.. its patented by them.. they spent millions to get their engines to say their name at stoplights.. part of their global campain effort!