Coolant flow
 

Ok, just want to be sure here.....

Today I flushed and changed the coolant in the 1983 300D. Took it for a spin, car ran great, excellent heat, and the temp gauge never went above 190 Fahrenheit (88 degrees Celsius). Got it home, and felt the radiator hoses, the upper one was hot, and the lower one was cold, so I'm assuming the coolant is flowing properly and the new thermostat is functioning correctly. About 10 minutes after shutting it off I carefully opened the cap on the overflow tank. To my surprise there was no pressure, and the fluid in the bottle was ice cold.

So, either everything is working fine (which I suspect), or I have a trapped air bubble/pocket somewhere.

Comments??

coolant circuit:


https://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Engine/617/20-005.pdf

Based on that diagram.... it is working as it should. Thank You.

It depends heavily on how long you ran the car and in what kind of conditions. If you just got it to operating temperature, or if it's cold outside and you were running the heat nice and hot, it's not unusual for there not to be pressure in the system or for the overflow bottle to not have hot water in it. The entire coolant circuit has to heat up to build pressure, if the radiator is still cold you won't build pressure and the hot coolant won't expand into the degas bottle.