Just looking for ideas on making a clean efan temp sender install.

I pretty much despise those prbes that goe between the clamp into the hose,

The best I've come up with so far is something like this: http://www.summitracing.com/parts/FLX-32082/?rtype=10

The thinking being I'd put a 180degree (or so) sender in the lower radiator hose.

BTW what is the lower radiator hose diameter?

What is everybody else doing? Is there a cleaner way? I hate a hacck job install.

 

You'll not get an accurate reading on the coolant temp if you place the sensor at the lower hose. By the time the coolant has reached to bottom hose, the radiator has already cooled the coolant. The sensor has to be at the top hose where the hot coolant first enters the radiator. Flex-a-lite makes several different styles of the temp controller where the temp probe simply goes in the radiator fins at the top of the radiator.

 

SPAL makes or used to make a sender that would replace the factory temp sensor and would work as the factory sensor for the PCM and hook into the SPAL controller.

The lower radiator hose is 1.75" diameter.

 

when i was running a e-fan i had it in the upper rad hose

 

I have a probe through the radiator fins, very close to the upper hose inlet. Its not quite as good as one in the hose itself, but I have my relay adjusted appropriately.

 

+1
the flex-a-lite controller is easy to use and not as much as the SPAL. Though the SPAL likely works better, the flex-a-lite is a capable controller.. all you do is spin the dial to the place/temp you want the fans to engage...

 

It depends on how you define accurate. That is likely a function of what the objective of your control is or mis/understanding of the system operation as the case may be.

Explain the err in my logic or tech if you'd be so kind. It could save me some work and/or cash to understand out why what I've come up with wont work before I get started heh.

Here is my thinking:

Control System Goal: ensure sufficiently low intitial temperatures of fresh coolant charges as drawn by cooling ciircuit during coolant exchanges intiated via thermosat heat cycling.

Assumptions:

1. Fans have been chosen that are capable of removing heat faster than the engine can add it in worst case operating conditions. IOW in normal operating conditions the fans can potentially operate at less than full duty cycle and still maintain proper cooling.

2 A set point (temp activated with hysteresis) triggered relay can be used to initiate cooling (turn on and off fans automatically).

3. Feedback should be based on accurate (as pssible) information about current status of coolant capacity for cooling.

3A. Coolant temp readings taken near engine coolant circuit inlet (lower tube) will more accurately depict total coolant system cooling capacity than would placing the sensor near the coolant circuit outletm (upper tube). This assumption seems reasonable to me since I believe the volume of coolant in the radiators is much greater than the volume of coolant in the engine cooling circuit. Also I assume that complete mixing via system vibration and convection currents occurs in the radiator shortly after thermostat heat cycling transient spikes in localized radiator coolant temperatures near the engine cooling circuit outlet.

3B. One thing I don't want is my fans directly tracking my thermostat heat cycling. Placing my temp sensor far from the upper hose reduces this "noise" as much as possible (doesn't it?).

 

well sir, you've got a grip on it for sure..

you will be more interested in a SPAL, or some other computer monitored controller.. there is one I read about (didn't get it because it was $300) that initiated as soon as you started your engine, which in effect eliminates the hysteresis of a 'temperature alone' initiated fan set-up.. (for those of you who don't know, and I was one a few months back: hysteresis is the flux between a thermometer and when it reacts.. you may have a temp set at 190*, but your thermometer doesn't react to that until 195*, and the same for falling temperatures)...

the computer initiated controllers come on with ignition- BUT, they put very little power to the fan itself- say, ~1 amp.. being a DC device, the fan reacts by turning commensurate to that 1 amp.. If it is a 12a fan, it will start out by turning 1/12 the speed.. As your temperature increases, so does the amperage and the fan speed..

this is a VERY good thing as it keeps the device from drawing a start-up amperage of up to 25a, which overloads circuits and crap fries..

these computer initiated controllers have three really big advantages:

-start up.. doesn't draw a huge load to get them going, because they slowly wind up WITH engine temperature.

-multiple devices.. you can run up to three fans with them (you may want one on your tranny exchange too is the argument), and those two extra can either slowly wind up, OR 'punch' the engine with full blast right off.. this would be good if you used two different sized fans.. say, one 1700cfm to handle everyday crap, and an aux 3000cfm fan to do the punching on a hot engine.. ever how you wanted to rig it is possible..

- these creatures tap into the diagnostics on board.. they don't need a probe or a independent thermometer of any kind.. they actually use your existing temp sensor/sender to do what they do..


I would like to try one don't get me wrong- I think the logic behind it is magic.. but they sure are expensive, and I've not ventured anywhere near hot with the flex-a-lite silly logic probe controller..

but they're out there Ugly1.. I think SPAL makes one, and I know Summit sells one (or two) of the high end ones.. The brand name has something to do with Dakota...

 

The object of the electric cooling fan is to help remove as much of the heat generated in the coolant by the engine as possible BEFORE it reenters the engine which is why the temp sensor should be placed as close as possible to the top hose or point of entry of the coolant coming out of the engine and into the radiator. The fan is removing the heat before it reenters the engine. By placing the temp probe in the lower hose, you will not get an accurate reading of the coolant temp as it leaves the engine and you'll be allowing the heat soaked coolant to reenter the engine before as much heat as possible has been removed. It's a lot easier and takes a lot less time to remove moderate heat from a liquid than it does to remove excessive heat. You're depending on the radiator alone to remove the heat without the use of the cooling fan as it cycles thru the radiator.

Heat is the #1 enemy of an engine and the faster and more of it you can remove from the coolant BEFORE it reenters the engine the better off your engine will be. Your theory of turning on the cooling fan according to the coolant temp as it enters the engine as opposed to when it leaves the engine is only going to allow the improperly cooled coolant to increase the engine temps even more. The only way you'll even remotely to get your theory to work is to set the start up temp of the controller at an extremely low setting so the cooling fan can do it's job.

 

Edit @drew: Sure there are certain merits to an all solid state solution like you mentioned. For the cost differential I can't justify it. I'll settle on a temp sensor I like and throw some spares in the toolbox for the money I'll save by going low tech. The relay/sensors are available in current ratings high enough to easily handle both my fans in parallel. I'll use enough copper (fuse protected of course) in the wiring so that it cant overheat even doing full duty cycle during the summer time with both fans. It may not be the bleeding edge but this approach has time proven track record of pretty good performance and reliability without breaking the bank. Bank breaking is something I'm unfortunately still sensitive to.