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Robert, Vauxhall Technician
Category: Vauxhall
Satisfied Customers: 4708
Experience:  Fully qualified 19+yrs exp/self employed technician in the UK
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I Have a 55 plate Zafira. Coolant level message came on intermittent,

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I Have a 55 plate Zafira. Coolant level message came on intermittent, went off after about 1 mile of running. Water level checked ,O.K. However now the water in the reservoir has boiled and the engine Management light flashes on.

What engine do you have exactly?

How do you mean boiled? the coolant bubbling or the reservoir lost all coolant?

What was the temp guage sitting at when this occurred?
Customer: replied 2 years ago.

Coolant Boiled in the reservoir leaving reservoir empty. Engine is 1.6 petrol No temp warning light came on


Ok..there as sensor on the reservior at the bottom as you see with a small 2 pin connector - thats the level sensor for the system - so shouldnt have any problem with that if it sensed the level changes - the boiling over could be a few things - first off would be an inspection of the actual expansion tank cap itself - If the cap doesn't make a tight seal, due to the rubber o-rings on it, the cap pressure release valve are knackered then pressure wont be allowed to build up inside the tank, which means the coolant will be able to evaporate freely an escape as steam, As your engine gets hotter, then lack of pressure means that the water will literally boil away.just like a kettle as you are an inspection or replacement of the cap might one place to start..The next would be for possible thermostat issues either stuck in position or open - i note you do mention the engine warning light coming up so the ecu must be detecting or at least stored codes so that agin would be something to have looked into to see what fault codes you have - the next steps to check for leaking headgaskets/leaks in the system is combustion leak test on the system aswell as pressure test on the coolant system and see waht that brings up..if the combustion leak test dye changes colour then its likely the headgasket has failed or stages of..if the pressure test shows a slow decline then you likely have a leak and that will need to be traced..but as above id say it might be worth changing the expansion tnak cap and then see how that goes..sometimes these can cause when they become faulty the same symtoms you have worth trying another cap..provided the threads on the tank arent damaged..
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