C4 Squeak When Pressing Accelerator

[jamesf2]

Hi all. First post here. I've been driving my C4 (1.6 2008) for a couple of months now, and it has developed an intermittent squeak when the accelerator is pressed. It's external, not the pedal itself. I've done some searching, but can't seem to find anything that sounds like my situation. This squeak occurs every time I press the pedal, and lasts for perhaps a quarter of a second. It's very noticeable when it occurs, but it isn't there all the time. It doesn't seem to happen when in neutral or the clutch is down. I tried to get a recording on my phone, but the sound is drowned out. I'll try and get a better recording to post, but does anyone have any suggestions of what I can look at in the meantime?

Thanks in advance.

[GiveMeABreak]

Are you sure it's not one of the drive belts - alternator for example? These can squeak as a result of a loose belt or the pulleys. It may only happen as you increase the engine speed. Pop up your VIN when you get a minute, but I suspect you have the electronic Accelerator (fly by wire), so there are no cables to squeak and I've not yet heard of an electronic one squeaking. If it doesn't squeak without the engine running then it's not that, but something related to the engine turning - so as I said, likely a belt, pulley or tensioner.

[white exec]

Belt squeak can be confirmed by squirting a bit of water (don't use WD40!) on the runnng side of the belt, to see whether the noise temporarily disappears.
Could also be a rubber engine mount, which squeaks as the engine moves.

[Stickyfinger]

Often a sign of a failing main lower pulley, they distort (damped pulley) and the belt loosens a tiny bit and slips.

[jamesf2]

Marc - VIN is VF7**************[VIN obfuscated, can be read by forum staff]

I've done a bit more driving around this evening and noticed it also often happens when I take my foot OFF the pedal too.

I'll try the belt water trick, but I reckon it's more of a metallic sound rather than a belt squeal. I'll see if I can get a decent recording and post back.

[GiveMeABreak]

Ok, so you put an 'M' instead of an 'N', but I've corrected it now

So confirmed you have the electronic accelerator pedal, so leave the engine running and get a friend to rev is slightly whilst you are looking at the engine compartment to see if you can hone the noise down.

It's possible it might be the timing belt pulleys if not the accessory belt.

[xantia_v6]

Possibly a free-wheeling clutch on the alternator pulley?

[jamesf2]

Ok, so you put an 'M' instead of an 'N', but I've corrected it now

So confirmed you have the electronic accelerator pedal, so leave the engine running and get a friend to rev is slightly whilst you are looking at the engine compartment to see if you can hone the noise down.

It's possible it might be the timing belt pulleys if not the accessory belt.

OK, thanks for checking.

There's no noise when in neutral though, and I'm not sure if I fancy sticking my head under the bonnet whilst driving down the road . It seems consistent with the initial "jolt" you get as you tap the pedal. So I'm wondering if it's clutch related, or engine mount as someone mentioned. I'll get back on it tomorrow as it's chucking it down now.

BTW Thanks for the fast response times. My previous cars have all been Vauxhalls and you're all a lot quicker than the folks on that forum

[mickthemaverick]

As you have fly by wire are you sure its a squeak and not a hiss that you hear?
I recently found a fault which was causing a very short sharp hiss when pressing or releasing the pedal while the engine was under load. That one was caused by a vacuum pipe connector leaking. May be worth checking!

[jamesf2]

Managed to get a recording. Turn up the volume and you'll just about be able to hear it. Each occurrence was caused by me putting my foot on or off the pedal.

[mickthemaverick]

Hmmmmm! I'd have to agree that sounds more like a squeak. In which case the only thing I can think of immediately is a dry track on the pot that the pedal operates, but that would happen under load and when free running so ignore that....thinking aloud..... possibly a squeaky butterfly in the throttle body which only squeaks when air flow is higher? .....I'll mull it over some more and come back tomorrow!!

[jamesf2]

I'm going along the lines of this being clutch related I think, as it's also noticeable when engaging the clutch.

It gets quieter as the engine warms too I've noticed.

[mickthemaverick]

Getting quieter as the engine warms implies that something is expanding slightly and reducing the rubbing which is causing the squeak... could indeed be many things but I'll stick with the throttle body for the moment... Could run a book on this one..