R32 Gtr Very Brief Overheating According To Ecu-Talk

[BunsenBurna]

Was out on a brief drive this afternoon to log some data via my consult cable using ecu-talk. I do this every week or so in different weather conditions to check for problems.

I had driven for about 40 minutes when I pulled into a service station to refuel. A look at the data at this point (while the turbo timer kicked in) showed me everything was fine, with temps not getting above 85 deg C.

After refueling and paying the petrol man (a total of about 5 minutes), I started the car again and quickly noticed the ecu-talk Water Temp gauge flashing, indicating the temp had exceeded the set value of I think 95 deg C. Very interesting I thought because as I was looking at the ecu-talk gauge, it was indicating 92 degrees but dropping very quickly i.e. within seconds.

So I drove down the road to my house and got all the data in to Excel. This is what I discovered:

At the point of turning off the car, temp was 85 deg C

~5 mins later upon restarting the car, the temp was indicated as102

A fraction of a second later it was 101

A fraction of a second later it was 100

and so on until 5 to 10 seconds later it was low 90s

A minute later is 90

As I started moving it dropped below 90 and once up to 70kph it dropped very quickly to below 80.

Can anyone explain this? Any guidance appreciated. Cheers

[Moodles2]

The engine block & internals are always hotter than the coolant, there will be a temperature differential. With the engine off, the block will slowly heat up the coolant about 5-15c but will cool off with time.

[BunsenBurna]

The engine block & internals are always hotter than the coolant, there will be a temperature differential. With the engine off, the block will slowly heat up the coolant about 5-15c but will cool off with time.

Thanks moodles. Do I need to be concerned that the coolant is going 100+ for a while when the car is off??

[Moodles2]

The cooling system will still be pressurized, so the boiling point should still be above 110c

[Mayuri Krab]

Thanks moodles. Do I need to be concerned that the coolant is going 100+ for a while when the car is off??

Do you notice any coolant boiling when it hits over 100 deg C?

Its usually noticeable in the overflow bottle or a bubbling noise around the coolant hoses, mine did that due to a worn out rad cap not holding proper pressure.

If it is not boiling then I wouldn't be too worried.

[mad082]

nothing to worry about since the car wasn't running. the coolant keeps flowing to a certain extent when the car is off so it keeps drawing heat out of the engine but not as fast and the coolant isn't being cooled much by the radiator. some cars with thermo fans controlled by the ecu don't have the fan come on until up around 100 degrees.

the fact that the temp started dropping as soon as the car started running then you know that your cooling system is working.