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Discussion Starter #1
hi guys
I just did ask the question on the maintenance page, but...
Does any one know what temp the thermostat open at on the 164 or a 2.5lt 75?
I'm only asking because the one in the 164 is made of steel and the 75 one is made from brass.

cheers Shane
 

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But Mad North-Northwest
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On the Milano 2.5, thermostat should start to open between 81-85C (178-185F) and be full open by 95C (203F).
 

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Discussion Starter #3
thanks, do you know of a cooler running thermostat to change to? we are having
40c days and the car is at 100c most of the time and lm trying to get it to 80-90c
 

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The maintenance manual says 188F for the 164. However, with replacement thermostats, it'll be whatever is embossed on the thermostat itself . . . . usually about 192F.
 

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But Mad North-Northwest
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thanks, do you know of a cooler running thermostat to change to? we are having
40c days and the car is at 100c most of the time and lm trying to get it to 80-90c
That's a common misconception. A cooler thermostat isn't going to help with that. The thermostat is going to be full open at 100C so a cooler thermostat isn't going to make a lick of difference.

Honestly 100C running temp shouldn't be a problem. Between the coolant mixture and the pressure the car won't boil over at that temperature.

It's *possible* your radiator may be old and a bit plugged up, I guess, and maybe that would make a bit of a difference. But 40C is a pretty darned hot day! I think you're probably doing okay if you can maintain 100C operating temp.
 

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A proper coolant mixture is theoretically good to ~260F at 15 psi system pressure, but of course, real life will probably put it a little lower. 100C (or 212F) is basically within normal for some 164's. Not to worry, as the system, if in good condition, will keep the coolant from rising above maybe 220-225F.

You might check the coolant temperature in a radiator end tank, or the thermostat, with an infrared temperature reading gun. They don't cost very much these days. You might find the gauge is reading high, as many have found out.
 

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Discussion Starter #7
"You might check the coolant temperature in a radiator end tank, or the thermostat, with an infrared temperature reading gun. They don't cost very much these days. You might find the gauge is reading high, as many have found out.[/QUOTE]"

We have the temp guns at work for about $70.00 I honestly never thought of that.
ta for the help mate :whistling:
 

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plus one on the check the thing with an IR gun. I swapped a stat on mine and got way higher guage readings. Thought to myself something was weird and I measured the temp at the Tstat on a hot engine and sure enuff the guage was WAY off. I dont recall the value but an in line resistor solved the problem. ciao, jc
 

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No worries, mate, she'll be right, lol.
 

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hi guys
I just did ask the question on the maintenance page, but...
Does any one know what temp the thermostat open at on the 164 or a 2.5lt 75?
I'm only asking because the one in the 164 is made of steel and the 75 one is made from brass.

cheers Shane
Normally, thermostat opening temps are 89C. For very hot climates there is usually a cooler thermostat opening at 82C. The cooler thermostat is often used incorrectly by people who mistakenly believe a cooler engine delivers more power. The reverse is the case. I'm not sure why the lower temperature thermostat is offered for severe high temperature environments but they are. In theory the engine cools more efficiently when the radiator is hotter. A lower opening temperature on the thermostat does not affect cooling of the engine except to slow the engine warm up period. Since ambient temperature might only get as hot as, let us say 50C, that is still well below the thermostat opening temperature.

The temperature gauge on the instrument panel is not calibrated so does not indicate actual operating temperature.

Most common reason for apparent overheating on these cars is failure of the low speed resistor on the fan shroud. The fan only runs on high speed and then only after the higher temperature is reached. The resistor can be bypassed.
 

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Good chance your gauge is reading 10-15F hotter than actual. With an IR gun take the temperature at the thermostat housing. That's where the temp sender is for the gauge. Coolant temp by the time it gets to the radiator may be different. With the temp switch for the fans in the radiator itself, the indicated temp on the gauge cluster may be quite different than when the fans actually trip on.
 
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