Coolant question

[stupidget]

I've got a 2004 Boxster S and noticed something odd about the coolant.

My car had been sat for about 3 days on drive and when I came to move it I noticed that there was a coolant leak underneath, roughly in the middle of the car.  I looked in the coolant tank in the boot and noticed it was quite low, so I topped it up.  I took it out for a drive today, about 15 miles and the temp stayed at just over 80, and just before I got back home the Temp light started flashing, but, the temp was still just over the 80oC mark.  I looked in the coolant tank and it had dropped slightly but was by no means empty.  I looked underneath the car and there were no drips or leaks, but, I could see on the drive that there was a slight line of coolant.

 

Anybody any ideas as to what's happening?

[stupidget]

Update - I've just opened the boot and could hear a very slight hiss coming from the (blue) expansion tank cap and the water level had dropped a lot.  Is the centre of the blue cap supposed to push in as mine doesn't?

[NSS]

Sounds like its a new cap time - 04 is the new version.

Ive had the same and a new cap solved it 

[stupidget]

@NSS Thanks mate.  I've just ordered one from Porsche in Wolverhampton so fingers crossed.

[edc]

Could be a leak from the bleed valve o ring. 

[stupidget]

Update on the issue.

I got the updated expansion cap from a local Porsche dealership (£18) and I thought it had fixed the issue.  However I got in the car today and I'd not even started the engine and the temp gauge light was flashing.  Looked in the expansion tank and the coolant was really low.  I looked under the car and could see a drip under the car, about a foot away from the door seal just in front of the rear wheel.  I noticed that there is a plastic tray so I pulled an edge down and quite a bit of coolant flowed out, not all of it probably about 100ml, maybe 200 at the most.

Anybody any ideas what it could be?

 

[NSS]

Have you any damp areas in the boot area ?  possibly your expansion tank has a crack which is quite common.

[PaulQ]

Is the leak just in front of the rear wheel. If yes sounds like the o rings in the bleeder valve are shot (there is a vent pipe that runs from the expansion tank area)

If more central then possibly water pump. 

As above check under carpet in boot.

[edc]

If the car wasn't even running then it's most likely cracked tank or the bleed valve. 

[stupidget]

I've lifted the carpet and polystyrene in the boot and it's bone dry, but, it is pretty damp under the carpet behind the drivers seat.

[stupidget]

Another update.

Topped the coolant up again this morning.  Drove it to get it up to temp and then drove it hard for a few miles.  This was about 3 hours ago and there have been no drips and the coolant hasn't budged.  Like I said previously, boot is bone dry and think the damp behind the drivers side is a red herring as it was p*ssing down hard here for 2 days and I've just noticed a tiny rip right at the bottom of the roof canvas on the drivers side.