On Fri, 4 Aug 2017 17:29:15 +0000 (UTC), Bram van den Heuvel
wrote:


What diagnostics can I do to figure out why the coolant gurgles after
shutting down?

This happened twice over the past two days on a 30 mile trip each way, both
days of which were pretty hot at around 90 degrees.

Temperature gauge is working as it goes from cold to middle & stays in
middle so the car is not overheating.

Yet, when I shut down the engine, it "gurgles" a bubbly sound.

I can simulate the gurgling sound by squeezing the upper hose, where I can
hear the air and fluid moving about.

I had filled the coolant tank to the Full level, but it spilled out a cup
or two onto the ground when it gurgled.

The fluid is "watery" and "brown" so it hasn't been changed in a super long
time so that will be the first thing after a flush that I do.

I will borrow a pressure tester at the local auto parts store, but that
won't tell me if the water pump is working. The belts are intact and the
fan spins, so, that doesn't tell me much either.

What diagnostics can I do to figure out why the coolant gurgles after
shutting down?

Off the top of my head, just guessing in no particular order:

Stuck or faulty thermostat (replace)

Bad clutch in the fan

Ensure the belt is tight enough and not slipping

YMMV