Hi, I have a 2009 Bravo 1.6 Diesel Active. I have owned it for 7 years without any problems, It has done 69000 miles, just over a week ago I was on the motorway doing 70 mph, after covering about 70 miles, the temp gauge suddenly went from normal to max and red light in a matter of seconds. I stopped, checked everything the engine didn't feel hot, fan wasn't running, no loss of water. Waited about 5 minutes, temp back to normal, pulled off same thing once I got upto 60/70 mph. Got towed home. Bled water system, run at 3000 revs for 20 mins, still the same, although heater doesnt start to work until after temperature has 'overheated', stopped and returned to normal. Changed thermostat and heat sensor, still the same. Has anybody experienced this?

Water pump or clogged internal radiator.

i'd install a temp sensor (thermistor) on the thermostat housing... and have a look at that .. to make sure if the temp is in fact rising or not.

If temp isn't rising.. it can be an electrical connection to the sensor... so a bad ground somewhere.

If temp does increase check the cooling system ... rad, pump..head gasket

I had this on my old jtd..
Stopped me from going to a forum event

Pretty sure it is eldctrical

Go for either..
An ECU reading to find what temp it THINKS you have.
Or
An extrnal temp reading.


IF .. it is actually that hot then the fan should run..

Did that happen??

( you can trigger the fan from the OBD port)

Charlie

If the temp suddenly goes to max red then it's 100% electrical problem, probability of temp sensor failure, low voltage or somewhere in the wiring. This thing usually happens when your battery is low your ECU starts to freaking out, but your case sounds different.