Water temperature gauge sender

[Ray White]

I am fitting a temperature gauge and the capillary tube has a female brass nut attached to the sender bulb. I assume it should be screwed into the radiator header tank but to do that I will need an adapter. I appreciate that the rad may not be the ideal place and might have fitted it to the rear cylinder head plate but that is being used for a heater take off.

Rather than make an assumption that may or may not be correct, I thought I would ask for some advice as to what I need to be searching for. The plug seems to be 5/8" diameter.. What thread would it be please ?

[Steve Simmons]

Mine is on the radiator also. A fitting is brazed in place on the rear of the top tank. You could probably use a bulkhead fitting with a seal also, instead of brazing. Fit it as low as you can, since the water level is never up to the top.

[Ray White]

Thanks Steve. I am hoping to find an adapter to fit the existing threaded hole in the rad rather than braze on a different fitting. The plug in the photo came out of that hole in the header tank.. I am hoping the threads in the sender nut and the rad are the same but they may not be and in any event I am not sure what they are. Would they have used UNF threads I wonder? I have my doubts. BSF? BSP? I just don't know.

I can, of course, use a thread gauge to establish the threads but where will I find a suitable adapter? If the search proves too difficult I will have to machine one but that would be the last resort....

Could this be what I need?
https://www.ebay.co.uk/itm/Hydraulic-Fi ... 2055904685

[Duncan M]

There is about one place on a TC where you can use a non British sized fitting, and it is so incredibly close with standard threads.....