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[amba]

Strange one this.

Noticed the other day steam rising from the n/s bonnet/wing joint when waiting in traffice after short drive from home.

Didn,t do it again all day although strong smell of coolant .When home following morning checked coolant level and it was about 1 inch from level so added around 0.5 ltr.Drove to work that morning and same thing happened.Waiting at traffic lights to join motorway steam again coming from under bonnet.Pulled over and could see a steady drip from n/s hitting exhaust down pipe.

Turned around and drove home slowly..no temp warning or low level ..car sat at mid point on gauge.Got home and let engine cool down.Again added 0.5 ltr to bring up to level.

Now this has happened again for the 4th day in a row..as if car doesn,t like having that much coolant and wants to dump around 0.5 ltrs.I havent touch temp controls on dash,they are set at 22 and dash gauge hasn,t gone beyond mid point.

Assuming it is HBV or associated pipework ,but why would it only dump that amount and no more ?

[Kevin Wood]

The pressure the system runs at will depend, to an extent, on the volume of air in the expansion tank since this takes up the expansion of the liquid, which will be constant. The more the level drops the lower the running pressure of the system.

The leak probably stops below a certain pressure, so it reaches an equilibrium where it no longer leaks.

To hit the N/S down pipe I doubt it's from the HBV, though. More likely a leak in the valley or possibly a core plug at the back of the head or the N/S head gasket.

The thing to do would be to remove the scuttle cover, plenum, manifold and intake bridge, then pressurise the system while it's cold. It'll leak more readily when cold so you should be able to see the leak.

[amba]

Cheers Kevin.

Thats now on my list of Bank Holiday jobs as wanted to get stuck in and replace o/s exhaust manifold gasket so will have it all pulled apart then.Fingers crossed its not head gasket or core plug though