Morris Minor Owners Club

Hi
Can anyone let me know how to connect an electrical Oil Pressure gauge.

I have gone for the electrical one rather than the normal capilary tube type mechanical one as it is to fit to a Fiat engined Minor.

I tried the obivious, using the wires to the oil pressure light in the speedo, but that was also abviously wrong! When the ignition was switched on the gauge gave full deflection and when the engine was started it went all the way back!

So any ideas please would be greatly appreciated.

It might have to be wired to the voltage regulator at the back of the speedo like temperature guages have to be or you can fit an inline one as mentioned in some other postings.

Hello Roger,

you need a sender unit that matches your instrument (transducer).

This is a pressure sensor that varies in resistance proportional to pressure. Much like a fuel gauge sensor does with level.

Alec

Thanks for this Alex.
Any suggestions where I can get this from? It is a Smiths Gauge.

I tried to wire it 'in line' last night. One way round the guage went to full deflection when ignition switched on and fully the other way when the engine started. Swapping over the wires and there was no deflection either way. I checked out the switch with a light and the light was on with the ignition on and off with the enginge running, so I am assuming the switch is working OK.

Can I use the same sender as the fuel gauge?

Roger

no you cant use the fuel gauge sender unless you want it to tell you how much fuel is in your tank?

without the correct sender there is no way to wire this to work as it stands. you need to do the following:

what you need is a new electrical oil pressure sender, which should screw in place of where the current oil pressure switch is on the engine (note that the current thing there is a switch on/off for the oil light not a sender which give a voltage according to pressure) with the new sender in place you could use the same wire and disconnect the oil light switch OR if you have a later car that does not have the oil filter clogged warning light you can use that spare wire.

once the new sender is in place wire the electrical oil gauge from the 10v regulator (that also feeds the fuel gauge light green wire) through the gauge and to the electrical sender and job gone.

search the web or ebay for an oil pressure sender, but they tend to be expensive, as much 20 odd quid since that's the 'brains' of that sort of system. This is why most go for the mechanical gauges, since they are cheaper. You might also get problems matching the sender to the gauge? I'm not sure how critical that will be.

Far far better to use a mechanical gauge - the electrical ones are notoriously inaccurate!

Ok I give in. It will cost a forune for the sender, I need to match the sender to the gauge and the mechanical one is more accurate!

I have a mechanical guage so it looks like I will be fitting this.

Bearing in mind the pressure switch will have to go onto a Fiat engine (Metric thread?) any offers of a suitable donor car where I can get the necessary item. I have also seen in other postings, someone has used a plastic pipe from the presure switch and the gauge, any comments on this?

Most places that sell the gauges also sell the capilliary tubing and adapter that screws into the block in place of the existing switch.

They should also be able to sell you a "T" piece adapter that will let you fit the existing switch (for the oil pressure warning light in the speedo) and the new oil pressure gauge tubing adapter at the same time, then you can have both working.

If you take the old switch along (assuming you go to a real shop / motor factor), they can match the thread there and then.

As far as plastic or copper for the tubing goes, plastic is probably more forgiving and easier to work with, but copper is more in keeping with the age of the car. (but then if it has a FIAT engine, I don't suppose that's important ).

If you use copper, don't run it straight to the gauge, but make a sort of "spring" coil of tubing, about 2 - 3" across, (wind it round your coffee mug a few times), to absorb the vibration and rocking motion of the engine, otherwise the copper will tend to fracture where it meets the adapter union.

Even though the Continentals use metric threads - many pipe threads are still 'BSP'!!! So check carefully - there is a good chance the standard T adapter will be fine.

Hello all,

one source of senders for Smiths oil pressure gauges is Jaguar, as used on such cars as the Mk 2 etc. But as BMCE says, notoriously inaccurate.

Alec