986 / 996 / 987 / 997 Cooling Expansion Tank Cap >>12 Porsche

99610644704 Genuine Porsche coolant expansion cap, the most up to date unit which ends in "04". We recommend automatic replacement on all models equipped with the coolant caps ending in "00" or "01." Units ending in 00 will typically leak excessively to the point of visual coolant pooling. Units ending in 01 often let off pressure resulting in slow coolant loss, but not to the extent of visual coolant pooling. Other units ending in 02 or 03 should periodically be inspected and tested but are not as commonly 'bad' as the earlier versions.