I'm looking at a radiator that has a 2 bungs in the radiator return tank used for a temp sensor. When I was talking to him he said he puts 2 bungs in. One is used to turn the fans on at 175* and the other at 195*. Using 2 seperate relays. I could see how this could be good for the fans , but how about the cooling of the engine? With the temp sender on the ret tank the motor is being fed the temp of the radiator, say it's 180* then runs through the motor and heats up. How much would it heat up before it went back to the radiator? Do you think it's a good setup? I like the idea. Whats your take?

If you look at the radiator the temp sensor would be mounted in the right tank.

If it senses temperature in the right-hand (cool) tank, the temp there is 30*-40* lower than it is at the thermostat housing; 195* in the right-hand tank would be 235* at the thermostat housing. Any senders in that tank would have to be calibrated to trigger at 40* lower than the actual engine temperature at which you want the fans to come on. Why bother with all that? Just put the sender at the crossover passage or thermostat housing to sense actual coolant temperature exiting the engine, which is what you're really interested in.

:beers:

If it senses temperature in the right-hand (cool) tank, the temp there is 30*-40* lower than it is at the thermostat housing; 195* in the right-hand tank would be 235* at the thermostat housing. Any senders in that tank would have to be calibrated to trigger at 40* lower than the actual engine temperature at which you want the fans to come on. Why bother with all that? Just put the sender at the crossover passage or thermostat housing to sense actual coolant temperature exiting the engine, which is what you're really interested in.

:beers:

Would it really be a 40* difference? He can make it either way. With the bungs or without. He recommended using it in the radiator. I thinking of putting the sensor in the drivers head, but I already have my factory temp gauge in the manifold and an aftermarket temp gauge in the glove connected to the drivers head. I don't trust the factory gauge thats why I have two. Here's a diagram of ho the cooling works. Let me think this out. .....If the sender is in the tank near the lower hose and say the thermostat controller goes off at 185* that would be the temp of the water entering the motor right? Now if the thermostat was in the manifold it would read a higher temp sooner and turn the fan on sooner. So your saying the temp going in the motor would be around 155* since you said it would be 40* hotter at the thermo housing..Am I on track? What would you recommend? Adjustible controller?

It looks like the two with the blue plugs in them are for tranny lines and the other one is for a LOW COOLANT LIGHT, but I guess it can be used for a fan switch. The one on the left side is the petcock. I would put the fan switch in the intake or the block, not the radiator. I have never heard of someone installing their fan switch in the radiator. Those bungs look like tranny cooler line hookups. I have my fan switch in my intake. Right next to the thermostat housing. The intake or the block is the BEST place for a fan switch. There you get the most accurate temp readings.

Having the fan switch in the radiator outlet makes sense to me. If the water at the outlet is being cooled by natural flow, why turn on the fan?

Having the fan switch in the radiator outlet makes sense to me. If the water at the outlet is being cooled by natural flow, why turn on the fan?

The temperature of the coolant exiting the radiator isn't important - what matters is the temperature of the coolant ENTERING the radiator (exiting the engine) - that's what you're trying to manage, and that's why the thermostat is located there. If it made any sense to put temp senders on the cold side of the radiator, you'd see it on production cars, and you don't.

:beers:

The temperature of the coolant exiting the radiator isn't important - what matters is the temperature of the coolant ENTERING the radiator (exiting the engine) - that's what you're trying to manage, and that's why the thermostat is located there. If it made any sense to put temp senders on the cold side of the radiator, you'd see it on production cars, and you don't.

:beers:

I'm not saying that it's the only way to do things, just that it makes control system sense. I didn't say that you put the temperature gauge on the outlet of the radiator, but that you could sense the temperature at the outlet of the radiator to decide whether or not to turn on the fan. There are two control elements, the thermostat/water pump to control the flow of water and the fan control to control the flow of air. If there is sufficient natural air flow through the radiator to keep the engine within the operating parameters, why run the fan?

There are a lot of things you see on the Camaros at this site you don't see on production cars.

I can see what onovakind is saying, but what if the coolant is right on the border of being too hot and the fan doesn't turn on? By the time it travels through the block and heads, it could be too late. Just my thoughts.

I could see the only way this will work right will be a adjustable thermostat. I have a temp gauge in the glove thats connected to the pass head and also a factory temp gauge in the console. The console gauge reads 1/4 when the glove gauge reads 190*. What I'll do is program it to go on at like 200* and off at 185* using the radiator location and watching the glove gauge.

If you have the intake port used and the drivers side head port used, then why not use the passenger side head port? I have my original light sender in drivers head, gauge sender in passenger side head, and my fan switch in my intake. The passenger head plug was a bitch to get out, but it came eventually. I had to use a generous helping of PB Blaster and let it sit for a day or so. Also broke a universal joint on it.

If you have the intake port used and the drivers side head port used, then why not use the passenger side head port? I have my original light sender in drivers head, gauge sender in passenger side head, and my fan switch in my intake. The passenger head plug was a bitch to get out, but it came eventually. I had to use a generous helping of PB Blaster and let it sit for a day or so. Also broke a universal joint on it.

The pass head is hotter I think than all the others. Either way I am going to set the temp unit to the gauge in the glove, Thats in the pass head. The radiator comes with two ports for senders anyway.

I'm looking at a radiator that has a 2 bungs in the radiator return tank used for a temp sensor. When I was talking to him he said he puts 2 bungs in. One is used to turn the fans on at 175* and the other at 195*. Using 2 seperate relays. I could see how this could be good for the fans , but how about the cooling of the engine? With the temp sender on the ret tank the motor is being fed the temp of the radiator, say it's 180* then runs through the motor and heats up. How much would it heat up before it went back to the radiator? Do you think it's a good setup? I like the idea. Whats your take?

If you look at the radiator the temp sensor would be mounted in the right tank.

I was thinking.. What if I had him weld the bung on the inlit side, near the top hose. That would be like it was at the thermostat, right?

I can see what onovakind is saying, but what if the coolant is right on the border of being too hot and the fan doesn't turn on? By the time it travels through the block and heads, it could be too late. Just my thoughts.

What if this scenario occurs with the fan sensor in any other position? How do you decide when to turn on the fan?