Elec Fan Temp Switch

[GreenZZZ]

Instead of plugging the carb heat line, has anyone installed an electric fan on/off switch in the thermostat housing. Got this photo from the ZTherapy thread..

That would be pretty slick place to put a thermo-switch. I bet someone has thought of this and figured out what works. Anyone?

[zKars]

Oh yes, did this a long time ago with a Painless wiring fan switch. Just plain don't like the rod in the rad fins type. Its just asking for trouble.

Just have to be careful with how far in the sender sits inside the thermostat housing so as not to interfere withe thermostat, and when drilling out and tapping it for 3/8 NPT or whatever size sender you use. Go slow and tap a little at a time, aluminum likes to crack.

Another option is to use a 280z/zx housing which has more spots in the front for sensors if you need to run the wiring out the front instead of the side (depends on what fancy carbs/EFI etc stuff might be in the way.

Jim

[GreenZZZ]

Nice!

Reading up on this. I put a thread gauge and tap on the stock thermostat and our Z's have a 1/4" BSP (British Standard Pipe) which has 19 threads per inch. The NPT spec has 18 threads per inch for a 1/4 inch ID pipe. I'm looking around for a 1/4" BSP switch.

Like Jim said, the Painless thermostatic switches come with 3/8" NPT. Tapping increases the hole size from a little over 1/2" to 2/3".

http://www.painlessperformance.com/webcatalog/largeview.php?SearchField=30111

[Curtis240Z]

If you go this route, it would be better to have the fan only work when the engine is running, because if it is allowed to run anytime the switch is calling, the closing of the thermostat will interfere with the switch reading and the fan will not go off consistantly.

Edited November 17, 2009 by Curtis240Z

[GreenZZZ]

Great point. What do you think about buying a temperature switch at a higher temperature than the thermostat by say 5 or 10 degrees?

[Curtis240Z]

Because the fan will be cooling off the radiator where the fan switch is not located, you will not get good control when the engine is off (with an operating thermostat). Changing the trigger temperature of the fan switch will not change things much.

I like the fan to come on and hold the engine temperature just below 180 degrees. Moving it higher would in my opinion defect the purpose.

[GreenZZZ]

I like the fan to come on and hold the engine temperature just below 180 degrees. Moving it higher would in my opinion defect the purpose.

I think I see the issue! Your Z probably hasn't hit a month of 105 degree heat!!! With a sunny day the air coming into the radiator off the pavement could be as high as 120. Holding below 180 is impossible here. I would think most folks in my neighborhood would settle for 210-230.

I would love to drive a Z in Hawaii. You are blessed my friend!

[GreenZZZ]

It looks like there are two versions of the lower thermostat housing. The earlier Z's have 1/4" BSP and the later (as reported in the ZTherapy thread http://www.classiczcars.com/forums/showthread.php?threadid=35909&page=4) have 1/2" NPT. The Painless Performance Product's thermostat switch with 3/8" to 1/2" adaptor should fit into the '73/'74 lower thermostat housing without drilling. :cheeky:

[Walter Moore]

The later housing is probably 1/2 BSPT, not NPT. The differences between the two are so insignificant that it is nearly impossible to tell them apart. The NPT fitting is 0.345mm larger in diameter and has a slightly different thread angle, but the same thread pitch. Neither of those differences would have any effect on the interchangeability of a tapered thread.

I only mention that because BSPT was adopted as an ISO standard, and is often encountered on pneumatic and hydraulic fittings in Japan.

[wa5ngp]

I realize this is a bit of shade tree engineering, but I had one of those adjustable thermostats from Jc Whitney with the bulb on the end. I put the end of that bulb into the radiator hose on the engine side and then used 2 clamps and lotsa gasket sealer and it did not leak. This provided me with an adjustable thermostat, albeit kludegy looking.

Since then since I live in Austin Tx I went with a flex fan and I've used the thermo switch for an idiot light in case I stop paying attention to the gauge some hot day.

don

[GreenZZZ]

Since then since I live in Austin Tx I went with a flex fan and I've used the thermo switch for an idiot light in case I stop paying attention to the gauge some hot day.

don

After that month of 105 we had in Austin in summer, I've been obsessing about the cooling system. Figure the Phoenix area Z's have figured this out years ago. Lots-o-Z's in Arizona.

[GreenZZZ]

Our Z Car Creations stainless bolts folk have a writeup on modifying a 280Z thermostat housing for this mod.

Z Car Creations Fan Install Instructions