[NC427]

Hi Kevin,

what you wrote sounds pretty familiar to the problem I was confronted with when I sorted the cooling issues on my DAX (no supertube) 6,4ltr CSB stroker.

Guess you are correct upon concluding that the bottle neck is the expansion tank being fitted lower than the top hose/inlet manifold.

Will try to attach two pictures to this mail.

What you could also check / do:

1) High flow water pump

2) Check if the radiator is fully working or if part of the
system is blocked.

3) When I bought my Dax the fans where installed in front of the
radiator which resulted in bad cooling. Installed them behind the
radiator which helped a bit.
Finally got installed a single high perfomance radiator which
resulted in a mayor improvement re colling system temp as well
as it imporved the oil-temp as I installed a drysump system
and the external oil tank is no cooled by the airflow of the
radiator fan too. fan is controlled via thermo-switch.

4) Radiator unit: Last but not least installing an aluminium raditor
unit helped to finally getting fully controlled cooling system
temperatures.

5) Thermostat: Points of view may vary but I would not run the engine
without a thermo unit. Had mine reinstalled and with the above
changes there is no problem at all. Even this summer with 33°C
outside and being trapped for more than one hour in traffic jam
with stop and go driving there was absolutely NO problem with
the water temp.

Good luck
Carsten