That does not sound like you have lost a lot of coolant.
The "normal" operating temperature is from 85 to 95, give and take. You can see up to 100, but not on an open road with free cooling, unless it is stinking hot! (it is not stinking hot in Denmark! not even by a mile)
The fan is only supposed to increase cooling in a slow moving or stationary vehicle. It should never come on on the open road.
Filling the cooling system on many cars, but especially the V6 can leave pockets of air, if not done thoroughly! That can cause overheating. They will typically be very sudden and quickly subside.
But there should be no spillage before you get much higher in temperature!
Maybe up to 115.
So, here are the scenarios (scenarii ??:shrug:)
1. You have overfilled the system, and it has coughed some of the water out.
2. The smoke is not smoke, but steam.
3. Your cap has had it. Do what you should do with May! Bin it and get a new!:getmecoat:
4. Your measurements are wrong, and the system is operating at a higher temperature, (air around the sensor).
5. You have another problem, maybe stuck thermostat etc.

I would firstly try and keep the cooling system full, to the mark and no higher! Monitor and top up if required.

And check the fan operation. It should indeed come on at about 102 or 104, but that should not normally cause water spillage, if the system is not overfilled.

Correction
 

That's for the 1.8 engine only Glenn. We're discussing a KV6 here where the fan starts at 100 degrees C.

Simon

There isn't a single optimal running temperature for any car engine. It will vary depending upon engine load, road speed and ambient temperature. The lower limit is determined by the thermostat and the upper by the radiator fan. In the case of your KV6 the thermostat will begin to open somewhere between 86 and 90 degrees C. According to the data it will permit full flow at 96 degrees C. As you already know, your radiator fan triggers at 100 degrees C.

So, provided your engine is running between those two limits you should not be concerned. If you monitor the coolant temperature using the instrument pack diagnostics you will probably find that, when on the move, the temperature is in the low nineties. If the car is then brought to a standstill, the 'ram effect' of cooler ambient air is lost and so the coolant temperature actually rises. When it reaches 100 degrees, the fan triggers to lower it to 96 degrees.

I'd therefore conclude that MG Rover expects the KV6 to operate within a temperature range of about 90 to 96 degrees, but short term excursions to 100 degrees are permissible. It's important to remember that variation is normal and always has been. That's why motor manufacturers design the temperature gauge to show a stable reading so that owners won't worry unnecessarily.

Does that help?

Simon :}

Hi again Mike. Thanks for your answer.

Have you bled the system using which method? MG Rovers?
I have keep using the car and the temperature remains somewhere between 90 to 94º but I have not been in a traffic jam again to test it.

I've top up the coolant to the MAX mark and nothing have happened since then.


Sure was not so much coolant lost as I would assume in this situations.
As I mentioned, this situation happened in a traffic jam, so it didn't reach 99º in the open road.

The cap wasn't changed but the O-rings were. for VITON ones provided by DMGRS.

The thermostat is not stuck otherwise when I turned on the A/C and the fan kicked in the temperature wouldn't drop down as it happened, I believe.

Now you mention about air trapped around the sensor, that would produce a quite significant fluctuation in the temperature reading, am I right?

Thank you very much for your kind explanation Simon. Then makes sense why MG Rover made the fan to kick in at 100º.

Can't wait for this weekend to do the bleeding by the book as mentioned. I didn't realize how easy is to get airlock in the coolant system of the V6. I've done many coolant bleedings in my 1.4 K series and never got airlock.

Pedro,

In answer to your question I used the same method that Simon mentions with the exception of the bleed screw which I kept opening while the engine was running until I was sure that there was a steady flow of coolant from it.

I got my 2004 V6 with new belts, thermostat, fan, for scrap money because an airlock defeated the professionals. Why, when the car is now running without a problem and you are monitoring the IPK / coolant, are you even considering refilling it?

Mike

Refilling is nonsensical unless you want to add fresh antifreeze or drain rusty coolant.
What is needed is just a top up, maybe two, with a cold engine and then some vigilance on an ongoing basis.

So after that incident and everything pointing to be an airlock, would not be better to bleed the coolant system by the book and make sure there is no air in the system?

Just an update:
Today I've driven around the city, everything normal, temp. was 93 when stopped and 90 as soon as I started to move.

Your car is normal & functioning, answer to your question: No

Regards

Well that's good news. I'm inclined to agree with the others that you should postpone the filling/bleeding operation and see how it goes. What would be useful is to find a traffic jam on a hot day! :D

Simon