850 water boiling problem

[gort]

My 850 has been running with a split water coolant expansion tank cap for 18 months. & never had any problem until today when boiling water spewed out of the top of the cap. I changed the cap but still the problem exists. (I thought the cap was meant to seal the tank!). Can anyone kindly give me any advice please?

[andy72]

does your fan not kick in?

[ruffday]

Could be a sticking thermostat or broken water pump or at worst the head gasket may have gone.
I would be looking more at the head gasket.
You should have changed the cap a long time ago if it was leaking.
The system is designed to work under pressure and the cap leaking could have been masking the problem for a long time.

[gort]

Originally Posted by andy72

does your fan not kick in?

Thank you for replying.

Fan is working

Temperature gauge normal.

[gort]

Originally Posted by ruffday

Could be a sticking thermostat or broken water pump or at worst the head gasket may have gone.
I would be looking more at the head gasket.
You should have changed the cap a long time ago if it was leaking.
The system is designed to work under pressure and the cap leaking could have been masking the problem for a long time.

Thanks for replying.

Only noticed the cap had a slight slit recently. Still I was a pratt carrying on driving!

Having car checked out today. Worried it is a head gaket, which would mean scrapping my lovely car.

[andy72]

Originally Posted by gort

Thanks for replying.

Only noticed the cap had a slight slit recently. Still I was a pratt carrying on driving!

.

"My 850 has been running with a split water coolant expansion tank cap for 18 months"

Mate, i wouldnt call 18 months recent!!. As the other poster said it could have been hiding an issue for a long time. If you have replaced the cap, then air is obviously getting into the system somewhere. do you have any split hoses? is your carpets wet etc. The head gasket is a obvious casue but is more likely something like the termostat sticking (mind you, that would make it not get to running temp).

[gort]

Originally Posted by andy72

"My 850 has been running with a split water coolant expansion tank cap for 18 months"

Mate, i wouldnt call 18 months recent!!. As the other poster said it could have been hiding an issue for a long time. If you have replaced the cap, then air is obviously getting into the system somewhere. do you have any split hoses? is your carpets wet etc. The head gasket is a obvious casue but is more likely something like the termostat sticking (mind you, that would make it not get to running temp).

Hi

I cannot find where I said 'recent'.

Took car to garge this morning and they said, without even looking under the bonnet,.it was definitely the head gasket When I mentioned possible thermostat they said as it was boiling up like a kettle, it was not the thermostat. Why is he so certain?

All rubber pipes looking brand new.

Not sure what you mean by, .....mind you, that would make it not get to running temp..........'When the water was streaming out, the engine temperature was normal.

[andy72]

Originally Posted by gort

Hi

I cannot find where I said 'recent'.


Took car to garge this morning and they said, without even looking under the bonnet,.it was definitely the head gasket When I mentioned possible thermostat they said as it was boiling up like a kettle, it was not the thermostat. Why is he so certain?

All rubber pipes looking brand new.

Not sure what you mean by, .....mind you, that would make it not get to running temp..........'When the water was streaming out, the engine temperature was normal.

You said on post one....cars had a split cap for around 18 months.
Then on post 5 you said 'i only noticed it recently'

Anyway.....

A stuck thermostat generally sticks open. This means that water can pass through it freely, even when cold. Normally they shut off the rad so it warms up quicker, then open to let the rad do its job when its up to a certain temp.

If its stuck open, it will take ages to get warm. If its stuck shut, it wont allow the water to circulate the rad.

I would take it somewhere else. Get them to check the stat first, always start with the cheapest option!

If thats ok, check all the water hoses for leaks. A nice bit of oil or grease ona rubber hose can make a 10 year old hose look new so check properly.

If all else fails it could be your head gasket. It will be leaking from water channel to external air so the system isnt getting pressurised.

[The Hooded Claw]

Originally Posted by gort

Thanks for replying.

Only noticed the cap had a slight slit recently. Still I was a pratt carrying on driving!

Having car checked out today. Worried it is a head gaket, which would mean scrapping my lovely car.

^^^^^there it is!!!^^^^^ Also take it in to an MOT station & get them to "Sniff" test the Expansion Tank with their Exhaust Gas analysiser if it registers Hydro-carbons then yer head Gasket is stuffed

[Luxobarge]

^^^WHS^^^

All good advice above, but to rule a H/G in or out I'd definately get a sniff test done - not dear.