goodoldjam Posted June 24, 2010 Share Posted June 24, 2010 I'm looking for a temp switch for my electric fan to install in the thermostat housing. I'm wondering what other people used and not special order items. I'm looking for 3/8 npt switch. None of the autoparts stores list the on and off temps or even the size. I figure somewhere 180 on range would be what I'm after. All i can find are write ups that use special order Jegs switches. There has to be a Ford or GM switch that fits the bill. I need to know a part number or a model of car. Thanks for any help. Quote Link to comment Share on other sites More sharing options...
goodoldjam Posted June 27, 2010 Author Share Posted June 27, 2010 (edited) I think i found a switch that will screw right in. A mid 80s 300zx has a switch that turns on at around 190 and i believe it's 1/4" npt or is it bsp? Anyway NAPA wants $50 for the 85 300zx fan switch, so I'm going to head to the junk yard and snag one from 87 and see if that works. The 85-88 Maxima with the VG has 2 switchs both are metric. If that doesn't working I'm going to tap it to m16x1.5, I found quite a few different ranges in that size for cheap. I was reading that some of mid 80s Nissans have a sensor in the radiator hose so I'll look for that also. Edited June 27, 2010 by goodoldjam Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 5, 2010 Share Posted July 5, 2010 (edited) IMO that setting is way too high. Ask KTM what he found out about thermal runaway at a stoplight after running on the freeway. If you use a 190 fan switch, you best be running a 20 or 24# radiator cap! I used a standard Hayes (there is another brand out there now with something identical) electric switch that puts a sensor in the radiator fins. Set to come on 10F above the car's temperature on a 110F day in Palm Springs when driving at 30mph in 5th gear. Worked great. I run a 160F thermostat, and have done so for decades. Edited July 5, 2010 by Tony D Quote Link to comment Share on other sites More sharing options...
goodoldjam Posted July 10, 2010 Author Share Posted July 10, 2010 (edited) I settled on tapping to m16x1.5, mainly because if i want to go colder the switches are fairly cheap. Right now I'm using a switch that should turn on in the 180 range. I do have the option of dropping to a 170. I will see how it works out since it's about as hot it's going to get here, probably nothing close to what you see. Edited July 10, 2010 by goodoldjam Quote Link to comment Share on other sites More sharing options...
goodoldjam Posted July 12, 2010 Author Share Posted July 12, 2010 IMO that setting is way too high. Ask KTM what he found out about thermal runaway at a stoplight after running on the freeway. If you use a 190 fan switch, you best be running a 20 or 24# radiator cap! I used a standard Hayes (there is another brand out there now with something identical) electric switch that puts a sensor in the radiator fins. Set to come on 10F above the car's temperature on a 110F day in Palm Springs when driving at 30mph in 5th gear. Worked great. I run a 160F thermostat, and have done so for decades. Your right I'm going to need to go colder. Sat and idled and for some reason the switch isn't turning on, so I bypassed it. It's 80 degrees and the car went to 200 and the fan barely could cool it, given the intercooler is now heat soaked and almost to hot to touch. The fan was just sucking hot air over a hot radiator. I may almost need another fan for the worst case scenario. Quote Link to comment Share on other sites More sharing options...
LanceVance Posted September 28, 2010 Share Posted September 28, 2010 I want to run an electric fan and use the thermostat housing sensor bungs, seeing as how I won't be using a bunch of them anyway. I think I found a switch with the appropriate range and thread size: HONDA OEM - 37780-PA6-003 Lists activation temperature as 70°-75°C (158° - 167° F) M16x1.5 thread size. Average price is around 40+ Would this work? anybody have anything more appropriate seeing as how this thread has gone a while without any developments? Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 18, 2010 Share Posted October 18, 2010 That looks a lot like the Honda Switch I had earlier in my car's lifetime. I went to an adjustable without a submerged element simply because it was easier to manage with stock radiator hoses. That switch seemed to work, but I was able to tailor my fan engagement. Now, for use in a differential oil cooler pump application.... posibilities abound! Quote Link to comment Share on other sites More sharing options...
zack_280 Posted October 13, 2011 Share Posted October 13, 2011 I think you can get some of the thread size info in this thread. http://forums.hybridz.org/index.php/topic/95507-thermostat-housing-sensor-questions/page__p__898377__hl__%2Bthermostat+%2Bthread+%2Bsize__fromsearch__1?do=findComment&comment=898377 Quote Link to comment Share on other sites More sharing options...
zack_280 Posted October 13, 2011 Share Posted October 13, 2011 I got some adapters from Summitracing. You can just search for NPT to metric adapter and you should be able to filter for what you are looking for. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted November 13, 2011 Share Posted November 13, 2011 Many of the chryslers don't turn on the fans until 230 degrees F. The reason for the high temperature is that they are sampling the temperature of the cylinder head itself instead of the thermostat housing. I run a M30 ecu on my L28et and use a laptop to pull data from the consult port and the temp sensor on the head is always a bit higher than the temps I deduce using the lookup tables for the brand sensor installed in the thermostat housing. Quote Link to comment Share on other sites More sharing options...
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