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radiator temperature probes

ehall

ehall

NAXJA Member
NAXJA Member
Location
Southern Maryland
does anybody know if the aluminum stick radiator probes read actual temperature or if they are calibrated to guess the coolant temperature through the radiator fins? like, if I wave one of them around in the air will it read air temperature or be off by ~50 degrees or whatever?

I'm thinking through options for a second electrical fan, and the FSM says the mechanical fan is designed to lock up at 190f air temperature on the face spring, so that is what I'm trying to copy
 
Now, mine is just a thermistor. Fan activation temp is set by fiddling with the pot on the controller. Shouldn't the temp of the fins be close enough to the fluid temps regardless?
 
hubs97xj said:
Shouldn't the temp of the fins be close enough to the fluid temps regardless?
Click to expand...
Well that is what has me bothered. The temperature of the fins will be way different from the temperature of the coolant in the head. For one thing the coolant in the radiator will be colder. For another the whole heat transfer thing happens by having heat migrate from the coolant to the fins and then to the outside air, so the fins have to be cooler than the coolant for the radiator to work. So if somebody wanted to use one of those long probes to measure coolant temperature in the engine the probe would have to be biased pretty heavily.
 
Yeah but actually I want to measure air temp coming off the radiator. I want to stick the probe behind the radiator and trip a fan based on that temperature, which is exactly how the mechanical fan works. I guess I will get a regular thermometer and one of these probes and see what I can come up with.
 
I'd just drill and tap another hole in the thermostat housing or reuse a block drain plug, but thanks for the link though :cheers: I'm still considering it since the Painless 30111 temperature switch is probably exactly what I need (maybe a little too aggressive considering the thermostat setting), but I'm still trying to figure out if I can mimic the mechanical fan closely at this point.
 
Maybe I'm missing something, but how would this be any different than any other temp operated fan control? Why air and not rad or coolant temps? Just have the parts on hand already, or is there something I'm overlooking?
 
sjkimmel99 said:
If you aren't tied into the radiator probe idea and can still choose a coolant probe with the electronic controller try one of these. Depending on the probe size you may have to plug the 1/4 NPT hole and drill and tap another of the appropriate size.

http://www.jazzproparts.com/SearchResults.asp?Search=GS-BW07&Search.x=0&Search.y=0
Click to expand...
actually the more I think about it that might be a really good idea to use that with the Painless tap in the lower radiator hose. the idea is basically to trigger the electric fan when the coolant in the radiator gets hot (as with long idles) so monitoring the coolant in the radiator would tell me exactly what I'm looking for
 
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