Help please, Foaming expansion tank, (head gasket???)

[Aaron7757]

Any help would be greatly appreciated. Well after forking out a small fortune to have the steering rack serviced on the wife's xc90 I've since discovered the expansion bottle full of foaming coolant. Have had the check coolant light blinking off and on randomly, hence the checking of the coolant level. Also the cars heating only blows cold for about 15/20 minutes. I've tried to attach a picture of the expansion bottle but not sure if it's worked. Thanks in advance for any help.

[cheshired5]

What colour is the coolant?
Is there an oily sheen on the coolant?
Is the expansion tank pressurised when cold?
Does the coolant smell of engine/exhaust/fuel?
Do you have white/light grey exhaust smoke?
When was the cooling system last interfered with?

[Aaron7757]

Thanks for replying.
Coolant is green,
No oily sheen,
Expansion tank is pressurised when cold,
Coolant smells normal,
I checked it last about 2 months ago when warning first came on but coolant level was fine and not foamy.

[cheshired5]

Originally Posted by cheshired5

When was the cooling system last interfered with?

With this question, I mean when was the cooling system last drained or refilled or topped up or maintained in any way?

[Aaron7757]

I wouldn't know as we only bought the car 4 months ago.

[cheshired5]

Best guess then is that a detergent flush has been used at some point and the remnants are foaming up.
Coolant level is low because follow up top ups haven't been done after a coolant change and whoever did the coolant change didn't really know what they were doing.

From your answers, there's no evidence of a head gasket fault.

[Aaron7757]

Thanks again for taking the time to keep replying. I hope you're correct and will definitely go ahead with getting a coolant change booked in tomorrow.

[diro]

Well, reading your 1st post I could image the scenario was or could be following:

garage been repairing steering rack of the car as you mentioned. obviously they had to drain the system. Once steering rack was repaired/replaced they had to fill up the system with power steering fluid but for some reason opened the wrong reservoir and started filling up power steering fluid into engine cooling system. After garage "specialist" realized he was pouring a fluid into wrong reservoir he had to flush coolant and somehow get rid off steering fluid traces. He maybe used Fairy or something else and thats why you have your engine cooling system foaming now
I know it sounds crazy but anything can happen.