Coolant leak.

[stecad]

Car is having a winter rest and overhaul. Last time out after a fast run there was a lot of steam in and around the engine bay while the turbo timer was on run down.
I've noticed that the coolant level is dropping - over a week it falls to a point were you can't feel it if you remove the filler cap and put your finger in. It then takes approx. 40ml to bring the level back to the top.
I've removed the undertray as part of a handbrake service and have not seen any coolant dripping onto the floor.
There seems to be a bit of corrosion (water mark) around the stat housing (the alloy block with the temp sender unit on) but this could be old.
There's no damp carpets. The pipes from hell were all replaced 2 years ago.
The hoses are original and will be replaced this winter with Samcos.

Any suggestions as to where the leak could be?

[Draven]

Are you getting lots of white smoke after the car is warm.. could be HG gone.

[stecad]

Hi Draven, did consider this but there are no symptoms to suggest HG failure. No oil emulsion in filler cap and exhaust runs clear at tickover and under load. The steam episode was after a good thrashing and rather embarrassingly when I pulled into the garage to fill up. It stopped when the turbo timer stopped the engine and didn't appear when I fired her up again. The steam was coming from the engine bay and not the exhaust. It's not happened since.

[MartinF]

Worth trying a new radiator/pressure cap as it could have failed and be allowing coolant back into the expansion tank too easily.

[stecad]

HI Martin, will certainly replace rad cap as part of winter renovation project.
The odd thing about it all is that the level is dropping while the car is standing in my garage. It's not a function of running the engine.

[MartinF]

How is the level in the expansion tank?

[stecad]

Just checked expansion tank this weekend and level is exactly where it should be. The previous owner replaced the radiator and the pipes from hell. The coolant in the expansion tank is nice and pink but there are signs of rust. Probably where the previous owner hadn't flushed the whole system out properly Will be addressed during the winter overhaul and as I change the coolant pipes (incl hose from hell).