307 1.6HDI 2007 - Coolant leak

[white exec]

You can check whether the tank cap is sealing properly - and pressurising the system - by squeezing one of the large hoses (eg radiator top hose) when the engine is hot. If no firm pressure is felt, system is not pressurised and will be prone to boil/lose coolant.

Might also be worth doing a test of topping up to correct level, and then allowing the engine to run until full working temperature is reached, and until the fan(s) cut in several times. Check system pressure as above, and watch for leaks.

One way coolant can 'vanish' is via head gasket failure, where coolant is drawn into one of the bores, and actually burnt off during combustion. If the coolant is standard glycol type, opening the throttle will produce a quantity of white smoke, as the glycol burns . . . just like stage smoke, or indeed vaping.

[khaleel01416]

You can check whether the tank cap is sealing properly - and pressurising the system - by squeezing one of the large hoses (eg radiator top hose) when the engine is hot. If no firm pressure is felt, system is not pressurised and will be prone to boil/lose coolant.

Might also be worth doing a test of topping up to correct level, and then allowing the engine to run until full working temperature is reached, and until the fan(s) cut in several times. Check system pressure as above, and watch for leaks.

One way coolant can 'vanish' is via head gasket failure, where coolant is drawn into one of the bores, and actually burnt off during combustion. If the coolant is standard glycol type, opening the throttle will produce a quantity of white smoke, as the glycol burns . . . just like stage smoke, or indeed vaping.

Thank you for your prompt responses this has definitely been the best forum in my experience.

I do now believe the only place it could be going is into the head itself as that's the only logical explanation. When hot my pipes get really hard and bulky so I'm guessing the caps doing its job.

Rules everything else out and seems like the last possible test I'll have to do is the co2 test will buy a pack of Ebay and lets see if we are indeed getting exhaust glasses into the coolant.

Will give you all a final update once the kits here.

Thanks again white exec you've been active and a legend in this post and thank you to all the genies that gave some very helpful tips and advice.