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1968 Camaro LS3 TH400 Moser 9” DSE mini tubs
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Marc,
I lost my diode before I did my install, and got some 1N4003from Amazon.
I had asked Northern Radiator for some information about the diode required. This was the response I received.

Diode description:

The diode needs to be leaded/through-hole (has wires). The part used in the kit is a 1N4002. It's a standard part number used by many manufacturers. The part does not have to be a 1N4002. A 1N4003 (a bit larger) will work as well. How the diode is used is very low power, so just about anything will work…
 

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Maybe I can shed a bit of light on this ;-)

The green wire on the controller can be used in many different ways, but for this controller it is used to force it off when the ignition is turned off.

How it does this is by not allowing 12v to go through the diode when IGN is on, hence effectively having the green wire disconnected. The diode is blocking 12v from getting through.

Once IGN is off, there are a variety of circuits attached to the IGN side that are connected to ground through a device. Think of it like a light bulb. One side of the bulb is IGN, the other ground. Once IGN is turned off, the bulb filament provide a ground pathway, and that signal makes it through the diode.

To test to see if the green wire does what it is supposed to, ground just the green wire (no diode) while the fan is running. The fan should shut down.

I too have have a Mark VIII fan in the Camaro, and it was the test mule for the controller. At first my thought was to have the fan off at key-off, but I've grown to like having the fan stay on for a minute or so after key-off (if hot enough.) It helps to blow some heat off the headers/engine compartment and gives me a verbal that the fan is doing what it's supposed to do.
 

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Camaro 1968, going along with a propane powered BPE 383 ci, T56, Eaton Posi 4.10:1, MCB Big Brakes
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I decided to live with the PWM still operating fan after shut down...

Guys I wanted to share with you the performance of the system getting the temperature right.

The rise in temperature is smooth and the 180°F is reach with no excess and then stabilize. Also, with engine idling the fan kicks in and the temps is kept at 180°C or the gauge needle almost stays there.
Inside the car, the fan is barely not heard.
When I drive the car staying at mostly low speeds on secondary roads and playing with the engine and gears I noticed 2 - 3 times that the temperature gets to 210°F rather quick than stabilize for some short time then decrease.
I guess (but not sure) this is due to the thermostat opening while the engine is requested for more load (at low speed so less forced air cooling), in this situation the time that the sensor feels the temps and kicks in the fan the temperature is quickly escalating...

210°F is not the end of the world and the engine timing can be better tuned with maybe a positive effect.

If there was something to do maybe it is to change the gluing tape fixing the sensor on the radiator. I don't like it because the sensor is so small I don't want to destroy it and now the glue is strong.

What do you think?
 

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I decided to live with the PWM still operating fan after shut down...

Guys I wanted to share with you the performance of the system getting the temperature right.

The rise in temperature is smooth and the 180°F is reach with no excess and then stabilize. Also, with engine idling the fan kicks in and the temps is kept at 180°C or the gauge needle almost stays there.
Inside the car, the fan is barely not heard.
When I drive the car staying at mostly low speeds on secondary roads and playing with the engine and gears I noticed 2 - 3 times that the temperature gets to 210°F rather quick than stabilize for some short time then decrease.
I guess (but not sure) this is due to the thermostat opening while the engine is requested for more load (at low speed so less forced air cooling), in this situation the time that the sensor feels the temps and kicks in the fan the temperature is quickly escalating...

210°F is not the end of the world and the engine timing can be better tuned with maybe a positive effect.

If there was something to do maybe it is to change the gluing tape fixing the sensor on the radiator. I don't like it because the sensor is so small I don't want to destroy it and now the glue is strong.

What do you think?
Your fan controller temperature sensor is on the output side of the radiator if I recall correctly. So it is controlling the temperature of the coolant leaving the radiator, not the coolant temperature where your temperature gauge sensor is. So I think it is operating as designed.

Maybe Carl will chime in.

Don
 

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Discussion Starter · #287 ·
I took the car out for a drive yesterday in 95 to 100 degree temps, stop and go traffic, highest it got up to was 202. Not sure I'm real comfortable with that, I would have thought it would do a little better. I'm not sure what I need to do from here to get it down a few degrees.
 

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I took the car out for a drive yesterday in 95 to 100 degree temps, stop and go traffic, highest it got up to was 202. Not sure I'm real comfortable with that, I would have thought it would do a little better. I'm not sure what I need to do from here to get it down a few degrees.
Where is your fan controller temperature sensor located? What is the target temperature? Where is your gauge temperature senser?

Don
 

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Discussion Starter · #289 ·
Where is your fan controller temperature sensor located? What is the target temperature? Where is your gauge temperature senser?

Don
Gauge sensor is in the manifold next to the t-stat, Fan/ecu sensor is in the head.
target temp would be anything under 200
 

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Gauge sensor is in the manifold next to the t-stat, Fan/ecu sensor is in the head.
target temp would be anything under 200
[/QUOTE
Is this what Andrew set up for you in your Holley ECU? What temperature was he targeting? Gauge is going to read higher than fan temperature sensor in the head by a considerable amount. I think it is operating as Andrew intended.
 

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Discussion Starter · #291 ·
Is this what Andrew set up for you in your Holley ECU? What temperature was he targeting? Gauge is going to read higher than fan temperature sensor in the head by a considerable amount. I think it is operating as Andrew intended.
the gauge is the one at the t-stat and reads lower than the head. The head is always 10+ higher than the t-stat sensor
 

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You are saying that the coolant exiting your engine is cooler than coolant further back in the head. I guess it might be. Any way if you want it a little cooler give Andrew a call since he set it up. He most likely can make it run cooler unless your fans are running 100%.

Don
 

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Discussion Starter · #293 ·
You are saying that the coolant exiting your engine is cooler than coolant further back in the head. I guess it might be. Any way if you want it a little cooler give Andrew a call since he set it up. He most likely can make it run cooler unless your fans are running 100%.

Don
Don,
I've got the handheld monitor for the ECU hooked up so I'll pay closer attention to the temps and confirm I'm speaking correctly. As someone else said on here, I reserve the right to be wrong.. lol
 

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Pretty sure Andrew can adjust the parameters to make it run a little cooler.
 

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Discussion Starter · #295 ·
Pretty sure Andrew can adjust the parameters to make it run a little cooler.
I sent him an e-mail, since I've put a few miles on it it's time for him to take a look at the data and see if he needs to make any tweaks to the tune as well.
 

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1969 Camaro Restomod
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Frank... Hope you get that stop & go temp sorted out. Hows it running temp wise on the highway when the fans are off? I would be thrilled if (when I get back out on the road again) to see 202° as the hottest mine got in stop and go traffic. Last Fall typically it ran about 195°-215° in stop and go, 220°-230° if I was stopped for a few minutes. That was before I re-did my wiring and switched the power and ground from the Junction block and chassis ground to directly connected to the terminals on the battery. I was not getting full voltage to the fans.
 

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Discussion Starter · #297 ·
Frank... Hope you get that stop & go temp sorted out. Hows it running temp wise on the highway when the fans are off? I would be thrilled if (when I get back out on the road again) to see 202° as the hottest mine got in stop and go traffic. Last Fall typically it ran about 195°-215° in stop and go, 220°-230° if I was stopped for a few minutes. That was before I re-did my wiring and switched the power and ground from the Junction block and chassis ground to directly connected to the terminals on the battery. I was not getting full voltage to the fans.
It would cool back down in to the lower to mid 190's on the short bursts of forced air between lights and low to mid 180's on the highway. I'm running a 180 Robert Shaw stat which is now EMP/Stewart "They feature a balanced sleeve design and are designed for high-rpm applications. These high-flow thermostats are recommended for any performance applications and work well with high-output water pumps"
 

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1968 Camaro LS3 TH400 Moser 9” DSE mini tubs
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Don,
I've got the handheld monitor for the ECU hooked up so I'll pay closer attention to the temps and confirm I'm speaking correctly. As someone else said on here, I reserve the right to be wrong.. lol
Just as long as you don’t have to exercise that right to be wrong as often as I do….
I’m watching closely as I’m getting closer to first drive.
We are in the low 100s in Texas…..that should put the high pressure cutout , on the A/C to the test. 😁
Along with standing idle temperature….
 

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Just as long as you don’t have to exercise that right to be wrong as often as I do….
I’m watching closely as I’m getting closer to first drive.
We are in the low 100s in Texas…..that should put the high pressure cutout , on the A/C to the test. 😁
Along with standing idle temperature….
"low 100s" 😓

It's in the 100s here most of this week, I never say "low" when it goes over 99, I say it's F K N Hot !
 

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Discussion Starter · #300 ·
You are saying that the coolant exiting your engine is cooler than coolant further back in the head. I guess it might be. Any way if you want it a little cooler give Andrew a call since he set it up. He most likely can make it run cooler unless your fans are running 100%.

Don
I've put almost 200 miles on it since this questiuon, The sensor in the head (ecu) runs about 5 degrees hotter than the sensor in the intake (gauge). The intake gets up to temp faster than the head.
 
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