moisture/condensation under rear trunk.

[Sylvian]

Above the coolant cap. Is this common? How would I go about getting this fixed if its not common?

 

[gazrawly]

I have exactly the same question. I have read that this can be a sign of the coolant cap requiring replacement but am not convinced.

 

[Glyn]

Replace the coolant cap if there is no other explanation for the condensation like topping up recently.
If the rubber seal in the cap allows water under pressure to escape there is nowhere for it to vent as the rubber seal around the coolant/oil filler area traps it, obviously the luggage compartment lid is cooler so the hot moisture will condense on the boot lid

 

[BartyB]

Ever since I've had my Boxster (986) I've had slight condensation on the boot lid above the coolant cap. Several times the OPC has investigated this but no fault has ever been found with either the cap or the reservoir.

My theory is that if the cap and reservoir are OK and there's no drop in coolant level, then this condensation is due to air being trapped in the space which gets heated and the moisture it carries condenses out on the lid. Just my £0.02 worth.

 

[Sylvian]

Tightening the cap solved the issue for me.

 

[notechmike]

Buying a new cap fixed it for me