Oil Pressure Sender Rover Engine

[phlip99]

I'm trying to figure out what the thread is for the oil pressure sender located in the oil filter head. It's the big boy at the top of the photo.
I thought it was 1/4" BSP but that's 19 tpi and o/d 0.518". Whereas the old sender that's come out of the hole is 20tpi and 0.495" o/d.
I have an adaptor that's 1/4" BSP but it just won't go in... 23 thou too big a squeeze!!
The new sender I have is 1/8" NPT so I'm trying to find an adaptor.

Any ideas??

Phil.

[phlip]

OK... I've found it... it's 1/2" UNF !!
Adaptor here for future reference...
https://www.merlinmotorsport.co.uk/p/ad ... dp-1-2unfa

Phil