My +8 (a 1996 3.9) has always indicated 95-100 degrees, going up to 115-120 when it’s hot. That was until it badly overheated recently and is now awaiting a new aluminium rad.
That is (admittedly indicated) far too hot, a Rover V8 engine should be run between 80-90 degrees. Prolonged running at temperatures above this can cause softening of the heads behind the exhaust valve seats, detonation and pinking along with a significant drop in performance.
Hi Simon, I’ve had the car for just over 10 years and it’s always indicated those temperatures, I’ve never had any pinking or performance problems and it’s always been serviced by BHM, so I’ve always assumed it’s just indicating wrongly. I’m no V8 expert though so I’ll get BHM to check it when they replace the rad.
Steve
My 1999 car which I assume is a similar spec to yours runs in the 90s, according the gauge, most of the time in summer. I have an 85 deg thermostat fitted and a deeper alloy radiator. During summer traffic jams, like the Blackwall Tunnel (one of the pleasures of living in suburban London!) the fan will be operating for most of the time. I think this late generation Rover V8 was specced to run at high temperatures in order to keep emissions down. I agree with Simon (and John Eales) that the optimum for the engine is 85 Deg , it may be possible to change the actual ruling temperature with a customised ECU (Lloyd etc ) but that would be an expensive option AND you might possibly incur emissions fails during MoT tests.
I too have rigged up a by-pass switch which I can now use when I observe the temperature climbing, and attempt to keep it down. I also operate it before stopping the car to try and alleviate the heat soak generated by switching off a vey hot engine by starting from a lower temperature.
Colin (Spanner Juggler) helped me spec the by-pass switch, and installation was very easy. I installed piggy back spade connectors on the otter switch and then took two light duty wires back to an unused switch on my dashboard. Once I had assembled the components needed it was less than a couple of hours job (even for me)
I now feel much more confident going through heavy traffic knowing that I have an additional control over the temperatures.
