Weird squeal/squeak from engine at low revs

[giraffeonastick]

Couldn't see anything like this on the search (apologies if my search has failed me)

In the last couple of months, had a really weird squeal develop on my Aygo mk1 Blue (2010 model, petrol). I think it sounds like a belt slipping, but I can't quite figure out what to look for.

The squeal happens at very low revs and only when the car is in gear. It seems more prominent on startup/when cold, and is audible from inside the car and out.

As an example; if I were to slow down to say 20mph in 3rd, when accelerating away I'd hear a squeal until the car was back up to 30mph and revs picked up. I don't have a rev counter but I'd guess anything around 1000-1500rpm. Happens in each gear but most prominent in 3rd.

I'm hoping it's just a belt. Car has only done 33k in its 6yrs and has been serviced regularly.

Can anyone suggest where to start? Difficult to diagnose from looking at the engine bay as it doesn't happen when idling! 
Thank you :-)

[alan333]

Probably the alternator belt slipping. It'll do it worst when the engine is cold, and worse still if you're using lots of electrics at the time. 

[giraffeonastick]

Thanks! Sounds about right; Bluetooth/radio/fan almost always on... and now into dark days it's lights too.

Any easy fix on it?

[mickburkesnr]

7 minutes ago, giraffeonastick said:

Thanks! Sounds about right; Bluetooth/radio/fan almost always on... and now into dark days it's lights too.

Any easy fix on it?

A new alternator belt. Once the belts start screaming and slipping they won't get better. A new one would solve it.

[giraffeonastick]

Thought as much. Don't fancy the hassle in the cold/rain so I'll book it in at the local indie place to see if they can change it over for me. I'd normally have a crack myself but I'm willing to let someone else have the hassle on this one!

[fordulike]

Could try a drive belt spray, which might cure the problem if it is slipping, due to the rubber hardening with the cold weather.

Car Drive Belt Spray

[alan333]

Assuming the belt hasn't ever been changed, 6 years isn't bad going.  Don't mess about with sprays etc, change it.

[giraffeonastick]

I figured that 6yrs was fine. It's in the garage today to get checked over. Now they said they changed the belt when I had it MOT'd and serviced in September, I suspect if they did it didn't get adjusted properly, or they didn't change it. I hope it's not the latter.

Will know more later. Appreciate everyone's advice, thank you.

[giraffeonastick]

All sorted. The belt that was replaced was slack and hadn't been tensioned properly. Garage had it sorted in ten minutes, now no squeaks.

 

Thanks for pointing me to the right thing!