where to fit a temp sesnor for a electric fan

[mpk490p]

hi all,
i fitted a 16" electric fan a couple of months back and ordered a digital adjustable thermostat, this had the sort you put in the top pipe from the rad but the question is, is this the right place for it?
as the standard stat opens the temp goes up (as expected) but ive found the fan still comes on when doing 30mph+ as it is messuring the temp of the water coming from the engine not from the rad, the standard temp gauge doesnt even get beyond 1/3 up so am i cooling the air to much? should i put the sensor in the bottom of the rad and set the temp at say 80c? that way if the temp of the water is too hot after going through the rad the fan will switch on

my school of thought is that Your fan is that your RAD is the key thing so therefor you want the fan going on when the rad can\'t keep up. When the fan switches on it needs to help the rad cool the fluid going through it. Put the switch on the bottom rad hose so when your on the motorway and the rad can keep up with the cooling requirments the sensor will be below 80c becuase of your forward motion the fan won\'t be on.

thoughts?

Mark

[David Nock (RIP)]

I remember cars I had that had electric fans and the sensor always seemed to be about half way up the rad, in the side. If no suitable side location, I would think you\'re right - the bottom tank or hose is the place, exactly for occasions when the rad can\'t keep up with cooling.

[mpk490p]

how about just before the beehive where it first leaves the engine?
http://mazdarx7.iougs.com/cooling.shtml

Mark

[shaunwil]

I fit mine in the upper hose as it said in the instruction leaflet. Doesn\'t the water come back from the engine on the bottom line ?? Thermostat is connected to upper hose isn\'t it ?

Shaun

[Prof]

I thought the thermostat on the engine held the water/coolant in the block until the operating temp was reached, then allowed it through the upper hose to the radiator. This allows the engine to get up to temp quicker.  Return to the engine is off the bottom hose. I thought it was normal practice to place the thermostat switch in the top hose, if the water coming out of the engine heats up too much, then the radiator isn\'t cooling it enough - hence turn the fan on to aid cooling

[mpk490p]

I thought the thermostat on the engine held the water/coolant in the block until the operating temp was reached, then allowed it through the upper hose to the radiator. This allows the engine to get up to temp quicker.  Return to the engine is off the bottom hose. I thought it was normal practice to place the thermostat switch in the top hose, if the water coming out of the engine heats up too much, then the radiator isn\'t cooling it enough - hence turn the fan on to aid cooling

i think i just have too much time on my hands!
im going to try a couple of things to start with
A) move the sesnor as close to the thermostat as possible (top hose)
B) up the switch on temp to 92c from 88c as the thermostat only opens fully at 90c
C) stop worring about it!!!

thanks all
Mark

[David Nock (RIP)]

I thought the thermostat on the engine held the water/coolant in the block until the operating temp was reached, then allowed it through the upper hose to the radiator. This allows the engine to get up to temp quicker.  Return to the engine is off the bottom hose. I thought it was normal practice to place the thermostat switch in the top hose, if the water coming out of the engine heats up too much, then the radiator isn\'t cooling it enough - hence turn the fan on to aid cooling

The circulation description is correct, but I would therefore expect you need to sense at the bottom of the rad, so that you only put the fan on if the outlet from the rad (not the engine) is rising too much. However.. I can\'t argue with Shaun\'s instuction leaflet.
Actually, you can probably sense at both points if you\'ve got an adjustable stat. You would turn the setting up for just-off-the-engine-sensing and down for off-the-rad-sensing?? If your stat is fixed setting you might need to sus out by trial and error where it\'s best Any thoughts?

[David Nock (RIP)]

Merc CLK senses about one third up the rad, on the other side from the bottom outlet.

[shaunwil]

Probably the best option is dual water temp gauges. One in the top and one in the bottom. At least you know just how much work the rad is doing.

Shaun

[mpk490p]

Probably the best option is dual water temp gauges. One in the top and one in the bottom. At least you know just how much work the rad is doing.

Shaun

thats on the i\'ll get round to it list so not long now!:D

Mark