Strange sound at engine start-up (ABS self-test or what?)

Hi soewhaty. Does your car have ABS? I've heard something similar on a car with ABS, it was a self test of the ABS pump just after start-up. If you have ABS, try resting your foot on the brake pedal when you start the car and see if you can feel anything?

Thanks for the tip! I think you were right. Here's what google revealed after a quick search:

The ABS computer does a power-on self test every time you cycle the ignition.

from
https://www.popularmechanics.com/cars/ho ... 1/2265091/

Here's another topic discussing similar issues:
https://www.enclaveforum.net/index.php?topic=10524.0

and another bit of info

Each time the vehicle is driven, as soon as vehicle speed reaches approximately 20 km/h (12 mph), the anti-lock brake control module turns on the pump motor for approximately one-half second. At this time, a mechanical noise may be heard. This is a normal function of the self-check by the anti-lock brake control module.

from
https://autorepair.about.com/od/glossary/a/def_ABS.htm

So here's what I did - when the engine was off I pumped the brake pedal a few times, which made it quite stiff. I did that on purpose and then kept my foot pressing firmly on the brake pedal and while doing that I turned on the engine. That in turn caused the mysterious sound (which this whole thread is discussing) to appear immediately after ignition, and almost simultaneously with that, the brake pedal become much softer and looser. So that made me think the sound was indeed a self test of the ABS because it clearly has something to do with the braking system. I guess the above sources indicate the same issue I am discussing here and as far as I see .. it's nothing to worry about, right?

One last thing - I am pretty sure my c3 does not have ESP, because I know where the ESP button on my c3 is supposed to be located at, but in my car it is not present, which made it clear that I aint got ESP, although I think the guy I bought the car from lied to me telling me it had it. Back then I didn't know a thing about cars so it was easy to fool me. It's not like I know a lot now, but anyway. So with the fact I dont have ESP in mind I then questioned myself - isn't ESP a combination of 2 things - ABS and Traction control (pls correct me on that if I'm mistaken). So thinking that I dont have ESP led me to think that I also have neither ABS nor Traction control. So now I am confused as to whether or not I have the ABS. Could it be that I have only ABS, but not Traction control, thus also not having ESP? How can I tell for sure whether or not I have ABS?

My c3 2023 makes the same sound and has since new don't know what it is but never bothered me .

Thanks for your reply. Ermm I also think it's normal cos it's been like that since I bought the car. OK, I didn't buy it new but still. HOWEVER, one of the mechanics here told me it's something with the bendix. The admins gotta help out on that one.

Hi, Soewhaty

Both my 2006 and the wife's 2003 C3s have ABS and I've never heard that noise when starting, or on any other car I've had with ABS
however! it did remind me of my fathers 1964 mk1 ford Cortina 15000. The starter motor was an inertia type, when you starter motor turned to start the engine
the Bendix (was inside the bell housing and would be exposed to any oil, dust or debris flying about) would twist out on a spiral slide and engage the starter ring gear on the fly wheel then spring back once the engine started and disengage from the fly wheel, the spiral would some times get clogged with dust from the clutch plate and jam, it would make this noise and cause the starter motor to then be turned by then rotation of the engine, until it was thrown back out, the engine turned off, or damaged the starter motor, we would remove the starter and clean and lubricate the Bendix or quite often replace it.
The C3s have a pre engaged starter where the Bendix is better protected and also moves on a straight slide but the slide could be clogged or the return spring damaged or weak causing it to momentarily to be turned by the engine. With both types of starter it wouldn't happen every time on start up but would get worse in time.

also, when you pump the brake pedal then start the engine the pedal will drop down and feel "softer and looser" due to the vacuum taking up for brakes to work with less effort

I'm sorry this is a long winded reply

chipmonk1212 wrote:Hi, Soewhaty

Both my 2006 and the wife's 2003 C3s have ABS and I've never heard that noise when starting, or on any other car I've had with ABS
however! it did remind me of my fathers 1964 mk1 ford Cortina 15000. The starter motor was an inertia type, when you starter motor turned to start the engine
the Bendix (was inside the bell housing and would be exposed to any oil, dust or debris flying about) would twist out on a spiral slide and engage the starter ring gear on the fly wheel then spring back once the engine started and disengage from the fly wheel, the spiral would some times get clogged with dust from the clutch plate and jam, it would make this noise and cause the starter motor to then be turned by then rotation of the engine, until it was thrown back out, the engine turned off, or damaged the starter motor, we would remove the starter and clean and lubricate the Bendix or quite often replace it.
The C3s have a pre engaged starter where the Bendix is better protected and also moves on a straight slide but the slide could be clogged or the return spring damaged or weak causing it to momentarily to be turned by the engine. With both types of starter it wouldn't happen every time on start up but would get worse in time.

also, when you pump the brake pedal then start the engine the pedal will drop down and feel "softer and looser" due to the vacuum taking up for brakes to work with less effort

I'm sorry this is a long winded reply

You are, by all means psbl, welcome to come with such long replies as they are helpful for me. So thank you!

If what you say that 'with both types of starter it wouldn't happen every time on start up but would get worse in time' then it seems like I have a serious problem here because for me this noise appears every time from a cold start. If I've been on any kind of run and then turn off the engine and then 2-3 min later turn it on again then I normally I don't hear the sound. But as I said, on a cold start when the engine has been off for significant time, I think I always hear the sound.

I guess that mechanic was right and I have to have the bendix taken care of. Thank you for your reply again!