Water leak by Coolant top up bottle.

[jag]

Hi again,
I have noticed over the last few days that I seem to have a water leak , it looks as if it coming from behind the coolant top up bottle. I am planning to have a proper and thorough look at it over the weekend.
The leak only happens when I top my bottle up to the max mark, it doesn't totally go empty, it seems ok just below the min mark. I think the leak is quite slow when the car is just parked up. But when driven or when the expansion bottle is under pressure it gets to below the min mark in about 25 minutes driving. Any one else experienced this type of leak by the expansion bottle - Any help / ideas  most welcome.
Many Thanks Jag

[renaultbiler]

Not an unusual problem

[Anders Dinsen]

I think there is a small water leak somewhere, where air can escape. This means pressure cannot be maintained to the same degree in the engine and the water starts boiling. The result is an expansion of coolant larger than normal, and it will leak from the header tank lid.

I think you should start looking for traces of water near the engine.

/Anders

[renaultbiler]

Not an unusual problem

Perhaps make my post a little more clear, it happends from time to time that these expansion tanks crack on the back side.

[Anders Dinsen]

Not an unusual problem

Perhaps make my post a little more clear, it happends from time to time that these expansion tanks crack on the back side.

Ohwell, that's another problem then

[jag]

Thanks for that Anders / Renault biller - I am hoping it's just a crack in the bottle, as it seems quite an easy job to replace the bottle. I will have a butchers on the weekend.
Thanks Jag

[jag]

I removed the bottle from the car last weekend and was about to put it back thinking it was filler cap that was faulty, when I saw a small hairline crack on the rear. So I blanked off the pipe holes and pressurried the botle with boiling water and the water started to leak from the crack.
I could n't get hold of a second hand bottle from anywhere, it appears as if they seem to sell real fast whenever someone is breaking an espace for spares. I wasn't going to buy a new one at nearly £90.
So I have managed to do a temporary repair that has stopped the leak. I have since done about 300 miles and not a drop has leaked.
What I did was get some sealant which is called 'stix all' and put that onto the exterior of the bottle. This stuff is so good it can withstand petrol and temperatures of +150 degress to -40 degrees and is extremely flexible. It can also be used on wet surfaces to seal the gaps.
I will replace the bottle when one comes up at the right price. But at the moment I am enjoying trouble free motoring in my espace.