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Topic: need an opinion

in Forum: C3 Cooling and Heating Systems


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need an opinion (3/13)
 8/25/07 12:06pm
eddie20875Lifetime Member
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Lanoka Harbor, NJ - USA

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1975 metallic blue coupe with t-tops,L48, t/t steering, black leather interior. 1990 L98, white/red leather interior, auto,a/c


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thanks bruce. i don't want to go too low but may change to a 180. fans sensor is set to turn on at 195 and off at 180. just don't want to overwork the fans. figuring if the water circulates earlier it might be enough to let the fans shut off for a bit.

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need an opinion (4/13)
 8/25/07 12:14pm
Gunslinger
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Frederick, MD - USA

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Your 195 degree thermostat is maintaing that minimum operating temp so installing a 180 might help. As it is now, if your engine goes below 195 degrees, the thermostat closes and brings it back to that temp...it never gets a chance to allow the fans to shut off.
need an opinion (5/13)
 8/25/07 3:05pm
lukesvetteLifetime Member
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HOWELL, NJ - USA

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[QUOTE=Gunslinger]Your 195 degree thermostat is maintaing that minimum operating temp so installing a 180 might help. As it is now, if your engine goes below 195 degrees, the thermostat closes and brings it back to that temp...it never gets a chance to allow the fans to shut off.[/QUOTE]
 
Dave,
 
Also make sure that the setting of probe or thermostat that kicks your fans on and off is in alignment with your main thermostat in the intake. If too far apart in temperature, this could cause the condition that gunslinger is describing. In other words, you wouldn't want a 160 fan and a 210 manifold = always running.....Wink
need an opinion (6/13)
 8/26/07 8:15am
eddie20875Lifetime Member
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Lanoka Harbor, NJ - USA

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1975 metallic blue coupe with t-tops,L48, t/t steering, black leather interior. 1990 L98, white/red leather interior, auto,a/c


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sensor is mounted in radiator right under upper hose. i feel a lower temp stat will do the trick for a couple reasons. it will give the fans a break first. the confusing part is it will also allow the engine to run cooler. as bruce said too low is no good but if you look at some of the threads in here alot are adding additives to get the temp lower. i guess it's like a recipe, a guideline that you follo9w and adjust it to what works best for you.

i think it will be better also after i shut car off. i had the fans hooked up to run after car was shut off and they would run forever. i feel because the stat closed almost like forming a vacuum that the water would not circulate to get the cooler water to the sensor.  disconnected that for now as i am killing the battery. i don't think it is the sensor or the relay as when i tested it to begin with it worked fine.

also thinking about using a slightly lower pressure cap. new cap was supposed to be a 15 but was 16 so i put back the 15 that i had. will do it one step at a time and change the stat and then go from there and keep you posted.

thanks for your help.Thumbs%20Up


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need an opinion (7/13)
 8/26/07 9:12am
1969 L46
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I am not a big fan of the probe type sensors.  I prefer the in-head or in-manifold type.  I have my sensor in the intake.  It turns on at 200 and off at 190.  I have been driving the car in 100 degree weather and no cooling problems.  Don't forget to install all of the seals around the radiator and in the nose of the car.  The air has to be forced into the radiator because of the angled design. It isn't natural for the air to go that way. It will find the path of least resistance.  Do you have a solid shroud with the fans?  If not, there is a lot of dead area where the air is not being pulled across the cores.  I have a solid shroud with four 1 1/2 inch holes to reduce overpressure.      
need an opinion (8/13)
 8/26/07 1:59pm
eddie20875Lifetime Member
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Lanoka Harbor, NJ - USA

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[QUOTE=1969 L46]I am not a big fan of the probe type sensors.  I prefer the in-head or in-manifold type.  I have my sensor in the intake.  It turns on at 200 and off at 190.  I have been driving the car in 100 degree weather and no cooling problems.  Don't forget to install all of the seals around the radiator and in the nose of the car.  The air has to be forced into the radiator because of the angled design. It isn't natural for the air to go that way. It will find the path of least resistance.  Do you have a solid shroud with the fans?  If not, there is a lot of dead area where the air is not being pulled across the cores.  I have a solid shroud with four 1 1/2 inch holes to reduce overpressure.      [/QUOTE]

the sensor for this is the type you screw in. the connection for it is built into the radiator. only problem i am having right now is they don't shut down after it cools as i have them wired to stay on after key is off. if i cut the power to one fan they both stop. instead of running one wire to sensor i redid it to two separate wires. technically shouldn't make a difference but electric can be strange. i may change sensor to the block and see what happens but will see what happens with the lower stat and wiring change.Thumbs%20Up
eddie208752007-08-26 11:02:06

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need an opinion (9/13)
 8/27/07 9:03am
1969 L46
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With the sensor in the radiator, the fans should only run until the coolant drops below the cutoff temp.  Running time after you turn the key off should not be too long since you are only cooling the liquid in the radiator.  There may be a grounding problem with the sensor.  Most sensors are one wire.  Do you have a ground from the radiator to the radiator support?  That circuit has to be complete for the sensor to operate properly.  Just a stray thought.
need an opinion (10/13)
 8/27/07 11:29pm
eddie20875Lifetime Member
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Lanoka Harbor, NJ - USA

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spal suggested adding a ground wire as that was a problem with a lot of installations. when i wired the fans hooked a ground wire to the mounting bracket othe fan so the radiator has a graound wire directly attached. one wire should all that be needed but with two relays something could be screwy. after a bit if i pulled the fuse on one fan both would stop. i should mention here both fans have separate fuses and sepate power feeds. thanks for your input.

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need an opinion (11/13)
 8/28/07 8:36am
1969 L46
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My dual spals have a ground wire attached to each motor.  I grounded them to the radiator support.  I also have two relays and two in line fuses and two sensor wires.  I ran each of them parallel.  One power source, one ground source and one sensor.  I ran the power wires to the ignition blade in the fuse block and both sensor wires to the sensor in the intake.  Your fans should not be continually running.  They should pull enough air to cool the temp enough to shut off and then start again when the temp climbs.
 
I don't know if you mentioned it before but do you have all the seals around your radiator, across the radiator support and the rubber dam seal below the radiator and one more thing, the chin spoiler.  If you don't have all of these things, the air isn't forced through the radiator.  It looks for the path of least resistence.
need an opinion (12/13)
 8/28/07 10:24pm
eddie20875Lifetime Member
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Lanoka Harbor, NJ - USA

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1975 metallic blue coupe with t-tops,L48, t/t steering, black leather interior. 1990 L98, white/red leather interior, auto,a/c


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Posts: 828

i have all the wiring correct. i wired it so the fans would run after you shut car off. as gunslinger stated that the fans coming on at the same temp the thermostat is set may be why the fans run continuously when the engine is running. it keeps the temp perfect but when it starts to drop below 195 the stat closes and reheats it right back up. my problem is after i shut car off the fans run continuously but i may have the stat causing the problem. i think when it closes at 195 the water doesn't circulate past the sensor right causing them to stay on. i installed a lower temp stat and will see what happens.

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need an opinion (13/13)
 8/29/07 4:22pm
1969 L46
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Putting in a 180 stat may do the trick.  If your sensor is in the radiator, the fans should shut off as soon as the temp gets below the shutoff value.  The coolant in the radiator will be dropped below the shutoff value pretty quickly once you shut off the car because the coolant stops flowing through the radiator.   My guess would be about 5 - 10 minutes max.  If the sensor is immersed in the coolant in the radiator, it should not make a big difference what temp the stat is.  However, you are right about it constantly cycling and making a difference when the car is running.

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