I installed a Champion radiator (CC701) but it doesn't have a hole on top for the coolant level sensor. It does have a petcock, and I'm hoping to remove it and use that hole for a sensor. The original sensor won't fit in that hole, so I'm looking for a sensor that has 1/4" NPT threads to match the hole. Any suggestions?

 

Even though the CC701 says it's for a 1979-1982, it's not even close to the factory configuration. Unless you have someone TIG a bung in the top, the rad will not accommodate a fluid level sensor.

Heck, the heater outlet isn't even in the right place.

Champion Cooling Systems CC701: All-Aluminum Radiator 1979-1982 Mazda RX-7 | JEGS

 

You're right, and the weird thing is the radiator I received doesn't have those discrepancies. I've done some digging and one of two things happened: 1) I got scammed and a cheaper no-name radiator was subbed, or 2) the CC701 used to be a little be different, more like the original radiator from my FB. Based on some comments I'm seeing, it's probably the second one, but regardless, I still need to find a 1/4" NPT sensor to go in that hole.

 

Lowes/Home Depot has a large selection of brass fittings/adapters.

 

Thanks. Will give that a shot. Went back to the original Facebook RX7 group thread where I saw this radiator discussed, and the cc701 was definitely redesigned. Guess I got one of the old ones, which works. Confusing. Anyway, I appreciate the replies. Good news is, my car was running hotter than normal, but now it's running nice and cool.

 

Same issue. The bungs have been made with a collar that prevents use of stock plugs, sensors and has to be cut back in places to fit the shroud.

on the Coolant Level Sensor, without a bung on top its useless. Instead, I ran a section of brass rod down into the overflow tank to ground the collant in it, then dunked the stock sensor at the end of the wire into the top of the overflow bottle down a couple of inches. Now, when the coolant overflow gets low, I get a dash light. Recognize that this doesn't prevent you from running the radiator dry if theres a problem with your cap or overflow system, but at least you have some indicator instead of none.
I'm in the habit of checking fluids regularly anyway.

 

LongDuck, smart idea. I might go the same route. Thanks.

 

That is a genius idea for having a low coolant light. I personally don't care and just run the car without one, since I also check every fluid in the bay before every drive, just to be sure I'm gonna make it home *most likely*.

I'd also give Menard's a try for a fitting. Bring in the NPT threaded petcock and the sensor you want to use and find an adapter. If the sensor you want has metric threads go back to the bolt section and find a matching bolt thread pattern. Then I'm sure you can look online and find an adapter to go from the male NPT of the radiator to a female metric adapter that will work for the sensor.

 

The only problem with an adapter—and maybe I'm wrong—is that it seems the sensor probe won't be as deep into the coolant and might go off more than I'd like.

 

This is true, I didn't think of that. When the system is pressurized I believe that it would fill this space though and close the circuit of the sensor? Think of what happens when you remove the radiator cap when it's hot, there's tons of pressure up there at the cap.

One other issue I'd have would be hood clearance, not sure whether or not this could be an issue. Just something to watch out for

 

Good point about the pressure in the radiator. I'll give an adapter a try. Thanks!