Temperature gauge adventure

[Rabbitt]

IMG_1953.jpg (50.68 KiB) Viewed 1126 times

Something supposed to be simple , but maybe it isnt. A bit of a rabbit hole
I have a 1957 803cc series II Positive Earth here in NZ.
1 : Have done my homework in the forums but probably only got a D- mark. Definitively , will a Smiths Temp gauge operate in a positive earth car. appears that the answer is NO ! I do have a voltage regulator but that overall option seems a dead duck.
2. So I have bought a mechanical gauge as suggested but of course there is no engine block source to tap into , therefore a radiator hose adaptor is required , which I have also purchased.
3. A couple of difficulties ... the sender bulb is too large for the adaptor insert hole tap (NTP) and most of these adaptors have a default thread size.
Also , even if the insert thread was correct for the sender bulb and it was possible to screw home , the end of the bulb would bottom out against the other sidewall of the adaptor itself. (even if the supplied thread adaptor is used giving more length.) So the sender is both too wide and too long !
Any ideas ?

[philthehill]

Get the right adapter !!.
If your hose internal dia is 25mm as I suspect it is having just measured a Minor top hose then this is the adapter you need with the 5/8" UNF thread.
https://www.merlinmotorsport.co.uk/p/25 ... aptor-ha25

You may need one of these to space the transmitter way from the hose adapter.
https://www.moss-europe.co.uk/adaptor-t ... -3-11k2846

[Rabbitt]

Thanks .. searched all over for 5/8 thread sensor sizes on hose adapters Ebay/Aliex/Temu and locally ... and all were default 1/8 NPT.
So this link is the first I have seen and will likely suit ... I will recaliper the hose internal again as I thought it was smaller. Cheers

[Rabbitt]

I’ve had another look around the forum and eventually found several replies on the same subject. very helpful. I actually have two hose adapters and have decided to tap out one of the sensor threads to a suitable size plus an adapter.
I managed to get a different gauge and sensor whereby the sensor was thin enough to fit through a 1/4 npt entry which will all work.
continuing to fit this to the top hose position i’ve now discovered that to get the adapter plus new hose sections at each end is a pain to insert and fit between the radiator and thermostat housing even with heating the two hose pieces to be flexible enough. There is not enough room to flex and manipulate properly. I may have to consider draining and moving the radiator left slightly to do this.Some of the forum discussions have asked questions about repositioning the adapter somewhere else such as the engine water tap or else elsewhere.
Quite correctly one member said that although some positions may not provide a definitive reading the main point is to establish a consistent reading. So, on that basis replacement in the bottom hose be okay? I realise that reading might be not correct but at least would establish median. The bottom hose is far easier. Are there any tricks with inserting into the top hose position that would make the problem easier?