MINI Cooper + Cooper S 07 - Coolant leaking from filler cap

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Wed 19 Jan 2011 15:01
MINI Cooper + Cooper S 07 - Coolant leaking from filler cap - Drage

My wife has a MINI Cooper and reported today that the heater didn't seem to be working as well as it should.

I had a look under the bonnet and noticed

1. Hissing and slight coolant leak from the coolant filler cap

2. I took the cap off after the engine cooled down and noticed the coolant level had gone down to 1 inch below the minimum so it has definitely lost a bit of coolant, i've topped this up radiator and heater is now reported as working better

3. Over the top of the engine is a black plastic cover with a "MINI" logo on it. There appears to be "dribble" of dried coolant stains on this cover coming out from the bottom of the logo.

4. There is a small amount of "mayonaise" in the oil filler cap, car usually has 2 runs of 10 miles/day.

Is this likely just to be a faulty filler cap or something more nasty like a head gasket? The car has done about 23,000 miles.

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Wed 19 Jan 2011 15:48
MINI Cooper + Cooper S 07 - Coolant leaking from filler cap - davmal
The filler cap often incorporates a relief valve to safely dissipate any excess pressure in the system. A head gasket failure could over pressurise the cooling system.
When the engine is cold and shut down, take the cap off and have a sniff, is it exhaust or fuel smelling?
Could just be a poor or incorrectly fitting cap, overfilled or slightly hotter than normal though.

Edited by davmal on 19/01/2011 at 15:49

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