Idler belt/pulley squeal

[Charlotte Darcy]

There was a squeal from an engine belt in my Fiesta in every gear while accelerating.  When at speed or coasting it was gone, only when under load. 

I brought it to my Ford garage and they replaced an idler pulley after saying the belt was twisted.  But I have just driven the car for the first time since the work today and the squeal is still there !!!

it has to go back at the end of the month for a new starter motor but what could the squeal be ? Getting fed up with a branded garage not being able to identify and fix the problem.  
 

C

 

[unofix]

The usual thing to change first (unless there is clear evidence of a faulty part) would be the auxiliary drive belt, in the good old days refereed to as the 'fan belt'

 

[Charlotte Darcy]

They may well propose to change that next.  The sound is not as loud as last time but it’s there.  I’ll have to let them know at the end of the month.  More expense.  Thanks. 

[RL123]

A little talcum powder on the poly V side of the belt usually stops the squeal temporarily as a confirmation test.

i did have a belt installed out of line on the crank pulley by one V groove but this squeaked from start up.

[TomsFocus]

Surely they fitted a new belt at the same time as the new idler?  It should be itemised on the receipt if it's a Ford dealership.

[Charlotte Darcy]

11 minutes ago, TomsFocus said:

Surely they fitted a new belt at the same time as the new idler?  It should be itemised on the receipt if it's a Ford dealership.

Don’t think so.  Just says ‘idle - pulley’ plus labour.  

[TomsFocus]

2 minutes ago, Charlotte Darcy said:

Don’t think so.  Just says ‘idle - pulley’ plus labour.  

Very strange.  The belts generally cost less than £10 so not worth refitting an old one.

Which engine is it?

[Charlotte Darcy]

51 minutes ago, TomsFocus said:

Very strange.  The belts generally cost less than £10 so not worth refitting an old one.

Which engine is it?

1.25 petrol. 2010 car. 

[RL123]

Is it the belt slip? You can usually get fan belt squeal blipping the accelerator in neutral from start up due to alternator load etc. Talc on the belt would stop the squeal temporarily as a check.

Assuming you haven’t heard it with the bonnet open, ie only when moving, can you be sure it’s belt noise.

is there a possibility it could be clutch slip or engine rock causing something to rub?

just ‘brainstorming’

[TomsFocus]

12 hours ago, Charlotte Darcy said:

1.25 petrol. 2010 car. 

Is it a non-air con model?  The only idler I can see for that engine is in place of the air con pump for the non-AC models.

This should be the genuine belt (£20) - Genuine Ford Fiesta Mk7 Mk8 1.2 1.4 1.6 16v Drive Belt V-Ribbed 1830909 | eBay

But you can buy good quality aftermarkets such as this one for £12 - Gates Alternator Fan Drive Belt For Ford Mazda 6PK1019SF | eBay

Without wishing to sound patronising, swapping the aux belt is a job that I believe you're more than capable of doing yourself.  Don't necessarily need to pay garage labour.  As above though, it's worth making sure it is the belt causing the noise.  You can even briefly run the engine without the aux belt fitted as a test.  If the noise is still there, you know it's not the belt or any of the pulleys.

[TomsFocus]

This is the belt run for a non-AC 1.25 Mk7.  It's a stretch belt so doesn't have a tensioner fitted.

Crankshaft - Waterpump - Alternator - Idler Pulley

[Charlotte Darcy]

Hi.  Thanks for all the responses.  I opened the bonnet for a look and I can see a new pulley and what looks like a new belt.  See photos.  

[TomsFocus]

Yes, that belt does look new.  

The water pump pulley looks very shiny so the belt could be slipping on that.  They start fully painted black but the paint does wear off over time.