2015 Porsche 911 Carrera 4 GTS. Purchased from the original owner in 2018 (3y 1m after initial delivery) with 98 miles. Coolant pipe started to leak intermittently in May 2020. It was an intermittent and a slow leak. I never had to add any coolant to the coolant reservoir. Then during my first two drives in 2021, the coolant pipe leaked each time. Although I am still under CPO warranty and if anything I trust my local dealer far more than the independents, I chose to fix this myself.
I found plenty of coolant leak complaints on various forums, but it seems 991 owners had them fixed under warranty. I did come across a Rennlister in the UK who clarified some of the questions I had.
The typical coolant leak in the 991.1 and 991.2 models. Some owners have had issues with leaking coolant pumps. Luckily I haven't...yet.
I didn’t want to drain the whole coolant system, so I parked my 991 in my sloped driveway with the nose down. By the time I set both back wheels on car ramps, the engine was far above the rest of the coolant system. I drained 8.5 liters of factory coolant. Upon filling, it took just over 8 liters and will get topped up after the next few short drives. I have a vacuum filler, but it was not necessary or used. I used a 1000 ml graduated cylinder and marked off each liter with an automatic punch and later filled in each punch hole with a permanent marker.
Text within brackets eg. (#25) refer to the parts in this diagram.
I removed the E10 Torx bolt - M6 x 12 (#30) that fastens the silver coolant pipe (#25) to the engine block. After removal of that fastener, that pipe can now be pulled out of the thermostat housing (#19).
I removed the E10 Torx bolt - M6 x 12 (#30) that fastens the black coolant pipe (#26) to the cover of the high pressure pump. Without removing that bolt, you won’t be able to remove the black coolant pipe from the thermostat housing (#19).
I removed the E10 Torx bolt – M6 x 16 (#29) that fastens the black coolant pipe (1) to the thermostat housing (#19). That black coolant pipe can now be removed from the thermostat housing.
Coolant pipe 1 is #26 in the Coolant Parts Diagram.
Coolant pipe 2 is #25 in the Coolant Parts Diagram.
Coolant pipe 3 is not shown in the Coolant Parts Diagram.
Shown is the coolant pipe retainer after the E10 Torx bolt – M6 x 16 (#29) that fastens the black coolant pipe to the thermostat housing (#19) is removed.
I removed the two E10 Torx bolts – M6 x 20 (#9) that fasten the guard plate (#22) in place. Then I removed the electrical connector that the guard plate covered.
