Hi, I have a "2006 MK2 Ford Focus ST". Every time I turn my car on (warm or cold engine) I get a horrible squealing sound... At first I though it was a belt but iv I rev my engine a little bit I get little pops but when its squealing the pops sound weird (hard to explain what it sounds like) but after 5/10 mins driving the squealing goes away! I'm not very good with cars and I haven't had time to go the garage. So I was wondering if you guys might have had or know what the problem could be? A friend mentioned the turbo. Thanks :)

next time its squealing spray something around the belt area and if it stops then you know its the belt

Does it sound like an old kettle whistling when it boils on a cooker?

Also try opening the oil filler while it's running - if there's strong vaccum/pressure (I can't remember which) there it's the oil diaphram unit failed. This is part of the closed engine breather system and allows turbo boost pressure into the crankcases. In some cases it can then lead to cam seals failing due to the pressure in there.

Common failure on pre-facelift ST's, later cars had a redesigned unit which fixed the problem. New unit is approx £150 and an hours fitting time for somewhere that have done one before.