I've seen it work in off road power equipment (slow moving - high rpm) in 100F + temps. Don't know how much change you would get at 50 F or 80F. It is used by guys at the track, because most tracks don't want slippery antifreeze spilled, so water and water wetter is used.

 

Thanks again Savannah, Been looking into this coolant system ever since one of the mechanics I dealt with told me "the truck was overheating and the gauge was broken, only registering half way" from the reading ive done.. (total virgin newbie with ZERO automotive knowledge) i come to the conclusion hes wrong and just doesnt know the English system.. the thing that does boggle me a bit is after about 10-12 minutes of sitting at idle the electric fan kicks on and doesnt shut down (at least I dont hear it shut).. but then I came accross this in the RAVE:

"In cold ambient temperatures, the engine temperature is raised by approximately 10

 

I, and others, have seen this phrase in the RAVE, but can't confirm that it actually does this, or how it would accomplish this. The D2 is supposed to cycle the electric fan on at 212 F, then off at 202 F. The stat is supposed to start opening at 180F, and be fully open at 204 F. One would think that in cool temps it would not be required to open 100%. You can watch the digital temp with a data reading code scanner or an Ultra Gauge. The engine computer monitors this digital signal, and sends voltage pulses to the temp gauge to keep it at 9:00, even though temp may vary a great deal. Radiator can be clogged inside (dexcool and other sludge) or outside (fins plugged with mud, leaves). If your electric fan comes on, and stays on, then your temp is not dropping and you should look into this further. Sometimes a parts store can demo their fancy code reader for no charge, and you can see the Coolant Temp.

 

thanks for confirming this Savannah.. I checked with my friends infrared gun but it was useless to me.. was getting all crazy reading and I didnt even know where to point the thing lol.. Im going to check with my local auto parts store.. to get a better readin.. well beside that I think I finally knocked out all the codes.. im waiting to run another scan to see if i can finally get this bad boy inspected..

 

I have pondered this same assertion from RAVE and my though of a possible control the ECU could have over the engine temperature is to create a lean condition. A lean condition could raise the engine temperature and thus return a hotter coolant from the block to the thermostat to compensate for the cold conditions.

Our condenser fan came on once or twice during the winter months but we are not taking any chances and will swap out the radiator this spring (have to do the power steering lines, minor leaky power steering pump and lower coolant hoses - you know the while I am at it approach).

We are also going swap cream thermostat for the European black thermostat PEM101020 as the black thermostat has the same hard spring but opens at 82 C rather than the 88 C stock cream NA thermostat. Not really concerned about an increase in CO2 but I am concerned about a head gasket or other heat related problems. I'll plant a tree.

2003 Discovery 125K with high miles service complete

 

If the thermostat opens at 180, and you added 50 to that, that would be 230. Ought to be able to see that on a scanner/ultra guage, even if meter is internally programmed to show 9:00.