Top up tank empty after 10 mile round trip

[Fun.]

Hi All

My expansion tank / header tank is full yet my top up tank (behind the number plate) contents are gone even after a 10 mile round trip. I have topped up to the max with water and then set off on short journeys twice this weekend and it's happened both times. Should I be worried? The expansion tank level has remained the same.

Any help appreciated.

Fun.

[itchyfeet]

Hi All

Should I be worried?

Fun.

yes, any fault with the cooling system is a potential problem waiting to happen.

[Fun.]

Thanks for your brutal honesty

[slowcoach]

It's going somewhere then- either a leak from a pipe join, or it's being blown out the exhaust via a gasket leak. Can you have a good crawl underneath while it's running, and see if you can spot any leaks?

[itchyfeet]

try driving 1 mile stop and check while engine running thenn drive another and stop to check etc. and see if its consistant.

I didn't think it drew from the top up tank until it cooled down.

I wonder if the top up tank is cracked.

[Mocki]

Does it only empty when the engine is running ?

By nature of the beast it should o lay empty as the engine is cooling down , so either the tank is split, the hose is split , or the cap is faulty

The engine running causes pressure to build up in the header tank , which would fill rather than empty the top up tank until the pressure becomes a vacuum as the coolant cools

[Fun.]

Thanks for getting back to me, unable to check things out tonight now but will look into it after work tomorrow.

I’ve had a look and think I can see a small crack in the expansion tank which won’t be helping at all I’m guessing.


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[Mocki]

Just to check, so we don’t get crossed wires,
Header tank is only accessible by lifting the lid off the engine bay , and has the pressure cap ,
Top up tank is behind the numberplate flap and is not pressurised .

[Fun.]

Yep, that’s exactly the right page


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[Mocki]

So which tank did you think may have a crack in it ?

[Fun.]

The header tank.


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[jas915]

My header tank got a small crack,but only leaked once coolant was warm.i would suspect a leak from the top up tank,as previously said the top up tank should in theory fill up a little when driving then empty slightly when cooling.could maybe try not filling the top up tank and go for a drive and see if the header tank level changes much,check regular as you don't want the header tank running dry.

[Fun.]

Thanks for all the suggestions, should get a chance to take Daisy out for a bit later and see what happens.

[jas915]

Where shouts in fife are you? I'm in cupar maybe I could come have a look?

[Fun.]

I'm in Dalgety Bay. Not exactly a short drive... You're more than welcome to venture this way though, don't want to sound ungrateful.