Running Hot, Adjust the Coolant Mix?

[rick3000]

I installed a new OEM Pierberg water pump.

The only other thing I can think of is that there is an issue with the actual radiators, but I have never had a WP impeller fail, so I don't think there is any blockage. The car warms up normally to 180 and stays there for several minutes, but then it just seems like the cooling system cannot keep up with the outside temperature and the temps start rising unless I'm going 50mph+ without stopping.

Everything is perfect in cold weather, the coolant temp sits a tick below 180 with the 160F thermostat.

[Topless]

Process of elimination. These are things that have caused 986 overheating in the past. Check off the list and see what you find:

* Totally clogged airflow between the rads and A/C condensers.
* Air bubble in the coolant causing intermittent overheating.
* T-stat stuck closed.
* Water pump impeller chunks in the head coolant passages.
* Reversed send/return coolant lines after changing the WP.
* WP impeller chunks blocking radiator passages.
* Failed rad fans

Good luck!