1994 944T

Purchased the car two years ago with 175K. At that time I did a freshening up that included (among many other things)a new Hepu waterpump, heater hoses, oil cooler hoses, lower radiator hose, flush and renew coolant.

At 178K the Hepu pump failed- coolant pouring out of the weep hole; saved from overheat due to low coolant sensor alert. I was 600 miles from home and the only pump I could find was a Duralast. Just prior to and after the pump failure I had a coolant reservoir that looked like the first image below. It was suggested that a hose was degrading but I wasn't able to find one that fit the bill.

At 181K the Duralast failed in the same fashion (shaft seals failed), again the low coolant sensor saved it from an overheat. I installed a new Hepu. I fill the system with water and over the course of a week drove and drained the cooling system everyday. At that point I installed a 50/50 G-05 mixture and have not had any trouble since (currently 190K).

That was my experience but I have no proven explanation for what was going on. If I were you I would keep an eye on the coolant level and if you don't have a low coolant sensor keep an eye to the temperature gauge.

Good luck,
Randy