overheating without heater

[Andy Graham]

Any ideas why a ’93 Chim wont stay below 95c with heater off even driving at 50mph, but runs at 85~90, never going over 90 even sitting in traffic with the heater on.
Have recently had a rad recore and a head gasket test.
Is it likely to be…
Thermostat not fully opening
Water pump getting old
Partly blocked heater by pass

….or all of the above

Andy

[bobs4c]

My '94 Chim has a similar characteristic. With the heater control to cold and no fan, the normal running temperature has often gone above the 90 mark, but stable. In traffic, I often turn the control to Red and this will reduce the temp quite quickly, and with the fan on will stabilise below 90 on the hottest days in traffic.

Bit hot in the car though!

With a new otter switch (the old one shorted and kept the fans on), different temp range, the temperature has stayed below 90, with the lever nearer cold than hot.

I don't think the temp values are very accurate, so if the characteristic hasn't suddenly changed, there's probably not much to be concerned about.

[IPAddis]

Andy Graham said:

Partly blocked heater by pass

That would be my guess.