Optimum thermostat temp setting for 1.8L Zetec rocket

[Mark W]

Hi all,

I'm trying to set the temps for my thermostat and cooling fan for my Rocket.

Currently I have a stock thermostat in the car which the Gregory's manual says operates 92-99 degrees (interestingly, when I look at after market replacements they start to open at either 88 or 89 degrees, not 92...). My radiator fan currently operates on the range 80-75 degrees, but it has a second option to set it to run 88-83 degrees - temperature sensor for this is basically at the inlet to the radiator. My temperature gauge sender is at the exit of the radiator.

So the quick folks will have worked out that my radiator fan runs constantly (thermostat in limited bypass till 92 deg, fan on at 80 deg). I find this really annoying as a) the noise is irritating when I'm stopped as I can hear it through the bonnet, and 2) makes no sense to run the fan when the thermostat hasn't started opening. I think there is a few degrees of temp loss from the engine to the radiator through the nearly 3m of plumbing. Please note my car was a rush job at the end and I didn't really think this through first time.

So I'm interested in folks feedback on what they have done? What have folks set their operating ranges for the thermostat and radiator fans?

I'm thinking I have three options.

1. Get over it and accept the fan running all the time
   
2. Increase the fan operating range to 88-83 or higher
   
3. Lower the thermostat operating range

Regards option 3 I've looked for cooler after market 1.8L Zetec thermostats (i.e. open at less than 88/89 deg) but I can't find any.

Thanks for any feedback.

Cheers,

Mark

[mawdo81]

Option 2 is probably the best imho

[gwnwar]

I would go with 2.. start to open 83>88 full open 100 just before boiling.. but have the fans come on after the thermostat is just about fully open like 97 degrees off 90 degrees. Engines need to be run at higher temps but not hot enough to boil over and blow gaskets.