Hi! As the title says, my MK3 Focus 1litre ecoboost coolant resovoir is full of bubbles! anyone have any idea what caused this? Please see attached picture.

Cheers.

Could be head gasket. What does engine oil look like on dipstick?

19 minutes ago, Comares2001 said:

Could be head gasket. What does engine oil look like on dipstick?

Thanks for the reply. The oil looks normal on the dip stick, what am I looking out for?

In the olden days, if you removed the oil filler cap and it had a 'mayonnaise' type gunk in it, that was an indication of a blown head gasket. Though that was in the 70s LOL Not sure if modern cars give the same symptom!

Sometimes but not always if head gasket leaks , coolant gets into sump so oil would look milky colour. If your not losing coolant and engine is running normally I would just monitor things but a compression test on each cylinder at a garage should show if the gasket is leaking combustion gases into the coolant. If it is you may also see a change in colour of the coolant.Another possibility although unusual is that you have a faulty expansion tank cap that is allowing air to enter the tank when its cooling although I would have thought if it was this the engine may be overheating and you may also see coolant level going down.

Get a sniff test done, this will tell if it's head gasket, most garages should be able to do it.

looks like someone's urinated in it😁 when was the fluid changed last looks pretty weak.- change and see if you get same symptoms.

I changed the coolant this morning, it seems to be fine now! Wonder what caused all of those bubbles? I'll keep an eye on it. Thanks for the replies!