Engine Temp and Oil Pressure wiring

[Elsa]

1971 IIA petrol 88". . . temp gauge not working. Also not convinced oil pressure is working correctly. (note: voltage stabilizer just replaced behind instruments, which fixed the fuel gauge)

Please bare with this non-savvy electrical guy. Attached pics show the temp gauge wire trail, and "fuel filter wire".

Ok... for starters, the temp sender unit seems replaced by a brass plug (pic 2). I have a new sender (LR 560794) but there's no "available" wire to connect it to at the motor.

What seems the correct temp wire to use (green/blue seen at temp gauge in pic 1), has apparently been repurposed. It looks to go from the temp gauge, through the bulkhead in black cloth harness, then later exit the harness just below brass plug (pic 2). From there it connects to a black wire (pics 2, 3), which connects to a light green/brown wire in a black plastic sheath (pic 3), that leads to the oil pressure gauge (pic 4). Meaning, currently, the temp gauge wire simply meanders to the oil pressure gauge.

1. Am I right in thinking: Remove brass plug, install new temp sender, and connect the green/blue temp gauge wire from the engine harness to it (pic 2)... instead of leaving that wire going to the light green/brown oil pressure wire? (diagrams seem agreeable, but?)

2. If #1 is correct, then the light green/brown oil pressure wire (pic 3) will now be disconnected - where should that go?

3. I see on same motor harness a wire coming off and connecting to top of oil filter (pic 5). Haven't succeeded in tracing it yet, though would have thought it went to oil pressure gauge. Thoughts on it's destination?

4. Fair to assume antifreeze will flow out when I remove the brass plug (pic 2)?

My primary goal, as close to original/stock as possible, is to, 1) get temp gauge working, then... 2) the oil gauge if possible.

Any clear guidance on each question would be much appreciated.

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[roverp480]

In your 5th picture the sender with the hexagonal body is the oil pressure switch which is connected to the oil pressure warning light. Assuming its original kit, the branch coming off at right angles should have the pressure sender for the gauge , its part number is 537138 and is about 40mm diameter (see Pic.) . What is connected at the moment? 13992
The LR Series Two Club has a copy of the parts book and wiring diagram for your vehicle on its web site , but you need to be a member to access it https://www.series2club.co.uk/public_pages/index.php

[jimrr]

good pics elsa. If you ground the + line on either the light or the guage you should get a oil low light and I believe the guage should peg.
you can do a continuity check between the ends of the wire and insure the guage, light and sending units are grounded. the senders obviously will be! ........ as P180 says without joining the club....... the wiring isn't complicated. you need to insure the correct voltage is going to the guages to begin with ..... (i don't know what that is) ...... then if it's going to the guages it should function if the senders are ok.
let us know

[Elsa]

Thanks @roverp480 and @jimrr

roverp480, Thx for p/n and oil sender location confirmation, as well as oil light wire info. In answer, the vertical brass looking bit is just a capped off post (better pic attached in this reply). I'll consult wiring diagram since I see sender is two prong, but only one wire seems to go to oil gauge from engine bay (pic 3 above, green/brown in black sheath). Perhaps one prong is ground? Anyway, it seems the vertical post just needs replaced by the pressure sender, along with attaching the green/brown wire to it, agreed?

jimrr, I believe it's 10V to the gauges, via voltage stabilizer I recently replaced. Thanks for the ground tip, which I did today, and both the engine temp and oil pressure gauges pegged respectively. Wiring/gauges seem all well, thankfully. Next I'll install the LR engine temp sensor I have, connect the wire, and cross my fingers. Will antifreeze flow out of the temp sender hole when I remove the current plug?

I'm stumped as to why it was set up as it is (ie: temp gauge wire routed to oil pressure gauge, and temp sensor removed altogether), but many thanks to you both for helping sort it...

13994

[roverp480]

Thanks @roverp480 and @jimrr

roverp480, Thx for p/n and oil sender location confirmation, as well as oil light wire info. In answer, the vertical brass looking bit is just a capped off post (better pic attached in this reply). I'll consult wiring diagram since I see sender is two prong, but only one wire seems to go to oil gauge from engine bay (pic 3 above, green/brown in black sheath). Perhaps one prong is ground? Anyway, it seems the vertical post just needs replaced by the pressure sender, along with attaching the green/brown wire to it, agreed?

jimrr, I believe it's 10V to the gauges, via voltage stabilizer I recently replaced. Thanks for the ground tip, which I did today, and both the engine temp and oil pressure gauges pegged respectively. Wiring/gauges seem all well, thankfully. Next I'll install the LR engine temp sensor I have, connect the wire, and cross my fingers. Will antifreeze flow out of the temp sender hole when I remove the current plug?

I'm stumped as to why it was set up as it is (ie: temp gauge wire routed to oil pressure gauge, and temp sensor removed altogether), but many thanks to you both for helping sort it...

13994
The gauge sender has one terminal with two Lucar prongs, only one is used in this installation. The electrical circuit is completed through the sender body . If you keep the radiator cap on when removing the plug in the head , leakage will be minimal especially if you have the new sender to hand and put your thumb over the hole whilst putting down the plug and picking up the sender to screw it in. 13995
Sorry for the poor picture out of the parts book.

[Elsa]

@roverp480, Much appreciate your help on all fronts. Happy the wiring can pretty much remain original.

I installed engine temp sensor. Gauge works. Ran the truck 15 min or so. On flat ground, needle likes sitting/touching just north of 'H'. At top of a hill it went as high as needle thickness below hot line. I didn't have phone with me so I mocked up attached images. Seems a little warm. Probably need someone to do infrared temp check. It's a LR sensor (560794) and the truck is extremely original, ie: no other groovy wiring or molestation beyond what this thread shared.

1399713996

Thanks once again!

[roverp480]

@roverp480, Much appreciate your help on all fronts. Happy the wiring can pretty much remain original.

I installed engine temp sensor. Gauge works. Ran the truck 15 min or so. On flat ground, needle likes sitting/touching just north of 'H'. At top of a hill it went as high as needle thickness below hot line. I didn't have phone with me so I mocked up attached images. Seems a little warm. Probably need someone to do infrared temp check. It's a LR sensor (560794) and the truck is extremely original, ie: no other groovy wiring or molestation beyond what this thread shared.

1399713996

Thanks once again!

The gauge is not a precision instrument, may be worth cleaning all the connections and checking that the voltage stabiliser is giving the correct 10V output