GTCharlie

I haven't seen this mentioned for this engine yet so I wanted to document it. It took a couple dealer visits to find it as initially there wasn't any visual sign of the leak or failed pressure test. It was a leak that got progressively worse over 2 months eventually draining down the back of the engine and created a good size pinkish puddle. It took a month and 2,000 miles between the last fill up and getting the low coolant warning & puddling.

Here are the service notes:

Found coolant bleed tube leaking coolant not allowing cooling system to hold pressure.

1.Drained coolant.
2.Removed throttle housing cover and intake air distributor.
3.Removed Secondary air pump and Vacuum reservoir.
4.Removed and replaced coolant bleed tube.

Reinstalled all removed components. Bled and filled coolant system.

(1) 946-106-026-60 Coolant Vent Line
(6) 946-110-146-60 Intake Manifold Gasket

2016 Cayenne S with 91,000 miles

garrett376

It is the same design as the 958.1 V8 coolant vent lines, so makes sense it would follow the same failure mode over time.

BrendonSF

I just had the same issue on my '16 GTS. But at 110k miles, I took it as an opportunity to overhaul the entire cooling system. It was over $1k in labor to remove the top portion of the engine, so made sense to replace the other componentry while they were in there.

F SANE IL

Same issue for me recently (past 100k miles). Same vent line that gets hard and breaks in half. Why did you need to drain all the coolant? Not saying it's bad, in practice it's good to change it out at intervals, but not necessarily required while doing this specific fix.

GTCharlie

Dealer did it. Probably just a service manual step.

F SANE IL

Oh ok. Makes sense then

mistermct

What else did you replace? I'm mid job now and have the intake manifold off.. there are hoses everywhere

BrendonSF

The shop "replaced all coolant related parts in the V of the engine." They found leaks from the thermostat o-rings and heater pipe. They replaced the thermostat, o-rings, and vent line based on the paperwork.