keep loosing coolant fluid through the tank over flow.

[REY]

Hi guys,

I have a vw sharan tdi if I drive it locale its fine but if I take a motorway for about 40min to 1hour drive the temperature goes over 90d and refill coolant sign comes on. Every time I stop to check and always the coolant fluid is emptied from the tank. I don’t really know what cause this, I took the car to deferent mechanic but no one seems to know the exact problem. They changed all this parts, water pump, thermostat, rad sencer, tank and cup, radiator. There is no sign of blow head gasket as they said no babbles no creamy oil and no leak. Could anyone please help?

Many thanks

 

[wotan]

The garage should have done a coolant test to determine if any products of combustion were present in the coolant, this is usuall called the 'sniff test', and involves a re-agent changing colour from blue to red.

Wotan

 

[Burnerman]

As above, but are you sure they changed the water pump?
John

 

[Mursal]

As above
If you switch the interior heating off (including air con) and run the car stationary until the electric fan/fans on the engine radiator comes on. By that time, I would think you will see the water blowing out the top of the expansion bottle. The fan does come on?
Then:
Radiator blocked internally bottom pipe never get hot
Radiator blocked on the outside, visual check
Thermostat needs taking out, see if the symptoms goes away/changes

Don't keep overheating that bullet proof engine or you will be in for a hefty bill. Always ensure after an episode, its well cooled before adding new coolant

 

[REY]

Thank you guys for the replies.

I will speak to the mechanic with your suggestions and see where it takes me.

I will update you with the progress.

Thank you again.

 

[hazetimesfive]

sometimes the hoses can develop splits which only leak when the engine is hot.

 

[regsmyth]

Sounds like what I had with my Alhambra.
It was a problem with the head gasket, which was allowing exhaust gases into the water when under pressure and forcing all the water out.
I ended up getting a second hand engine put in.
Expensive.

 

[Mop]

Sadly I would suggest a head gasket failure also ....... OUCH ....... Sorry

 

[jctilingservices]

silly question really, but do you have either white smoke coming out of the exhaust, or is water dripping out, because your symtoms seem to point to a leaking head gasket OR a faulty water pump, but you say this has been changed