Thermo fan switch

[pedro]

Couldn't get an ice thermo fan so i bought a tornado brand one, supposed to be the most powerful with 3,300 cfm, only problem is the temperature switch is too big it's a 3/8 BSP thread and the old one is a lot smaller, tried to find a smaller one on e-bay and through google but no luck, I don't even know what size the old one is, any suggestions.
   Pedro

[Harv]

Pedro,

Some options:
a) drill and tap out the thermostat housing.
b) fit a steel sleeve with the threaded connection already in place (from SuperCheap) into a radiator house.
c) use one of the Davies/Craig "under hose" switches.
d) adapt up to the original hole with a brass fitting (looks like the new sender has enough thermocouple depth to allow this without being out of the water flow).

Cheers,
Harv

[pedro]

Thanks Harv, the steel sleeve from supercheap sounds like a good option, depends how long they are though i'm running out of hose with the filter in there too, I think the housing would be too thin if i drilled and tapped it there's not much meat in there, do the Craig Davis ones go under the hose i was under the impression they had to be fitted into it, that would have to be the simplest way around it i'll go and check them out.
  Pedro

[jack_fc]

Pedro, they go under the hose... need to fit them very carefully and gently. Can be a problem to seal after refitting hose and clamp(s).

Best to use a sealant around the capillary where it fits under the hose, and check carefully for leaks at full coolant pressure/temp...

I recently used Sikaflex; worked perfectly, but may cause issues when I have to remove the hose...

The Craig Davies switch has adjustable cut-in temp setting, and usually needs a bit of time/experimentation to get the right compromise between

coolant not getting too hot and fan cutting in when not necessary (some people think most thermo fans lose efficiency as they get more hours on

them; I tend to agree. Best not to have them running until they're needed - save fuel too  )

I've used these switches on my last 3 cars and had no real problems.

cheers, jack

[pedro]

Thanks Jack, ended up buying a Davies Craig switch, there was no more room in the top hose for the adaptor, one more problem solved. 
   Pedro

[jwm]

Part No. 0401 is the Craig Davies switch with the hose probe or you can go for the 0402 which has a probe that fits in between the fins in the radiator. The 0402 is a little bit harder to come by.

[hsv-001]

Put one of these under the top hose and wire it through a light up toggle switch on the dash. If you switch it on the earth it will light up when the  dial up thermostat gets hot and earths, or when you turn it on with the switch because your fan should come on when the thermostat earths your relay. Yes they are tricky to install under the hose as they need a neat fit around the unit. I made a rubber shim from a offcut of radiator hose, cut a light groove in it with a grinder and tapered the sides. If you decide to use the factory thermostat you can still use these as a back-up.