I'm going to paste the instructions I wrote up into this thread, but I have a .pdf that is better formatted if anyone wants to host it for others to download. In the .pdf, the figures are located within the text and have the labels that are referenced in the text. Hopefully this is still helpful. Bryan

Oil Pressure Gauge Installation
2003 Land Rover Discovery SE
Author – Bryan H
www.landroverforums.com

Materials

1. Oil Pressure Gauge
• Cyberdyne A010E160Y Oil Pressure Gauge Kit (Green Digital Display)
• Includes Sending Unit
• Purchased on Ebay - $42 plus $6 shipping
2. Metric Adapter
• 1/8” NPT to M12 x 1.5 Metric Adapter (Converts metric threads in engine block to NPT)
• Purchased from Summit Racing - $8.95 plus $4.95 shipping
3. Miscellaneous Brass Parts (Purchased at Ace Hardware)
• 1/8” NPT Nipple (Male Threads on Both Ends) - $1.49
• 1/8” NPT Tee - $5.58
• 1/8” NPT Street Elbow - $3.19
4. Fuse Block Splice (two total)
• ATC Add-A-Circuit
• Purchased at Advance Auto Parts - $6.49 x 2 parts
• Also Need Two 10 Amp Fuses For the Add-A-Circuits
5. Other Supplies
• Zip Ties
• Electrical Tape
• Electrical Connectors (i.e. crimp, twist-on, or solder)

Installation

1. Disconnect negative battery cable.
2. Unplug connector from factory oil pressure switch and remove switch from engine block. Figure 1 shows the switch and wire harness connector. The switch is located just above the oil filter.
3. Modify the brass Tee by drilling and tapping the 1/8” NPT opening in the middle of the Tee with an M12 x 1.5 tap. The tap I purchased called for a 27/64” drill. See Figure 2 for more detail.
4. Preassemble the Metric Adapter, 1/8” NPT Nipple, and modified Tee. See Figure 2.
5. Install the Metric Adapter (including the crush washer), 1/8 NPT Nipple, and modified Tee to the engine block.
6. For my installation, I had to install the aforementioned items without the street elbow attached due to clearance issues. Once the adapter, nipple, and tee were installed, I was able to attach the elbow (I had to grind down a few of the elbow’s edges to reduce its overall size so I could squeeze it in. There is not a lot of room to work with down there).
7. Attach the factory pressure switch into the Tee (using the tapped hole).
8. Attach the new pressure sending unit to the street elbow. I turned the sending unit at about a 120 degree angle from the pressure switch for clearance. The pressure sending unit installation directions specified that no sealant tape or liquid can be used. The sending unit relies on its connection to the engine block for grounding purposes.
9. Reattach the factory connector to the pressure switch. See Figure 3.
10. Connect the signal wire to the sending unit (see the red connector in Figure 3).
11. Route the signal wire to the inside of the vehicle. I followed the loom that can be seen in Figure 3 to the top of the engine, then across the intake manifold, behind the brake master cylinder, and through the firewall using the same grommet that is used by the hood release cable.
12. The oil pressure gauge requires a +12 V ignition source, a switched signal so the gauge dims when the headlights are turned on, connection to the signal wire from the sending unit, and a ground.
13. I decided to use fuse taps to pull the 12 V ignition source and the light switch signal. The taps replace a fuse and include a wire lead for the accessory you are connecting. I used a ground located just to the left of the grommet shown in Figure 4. The fuse panel located behind the trim panel below the steering wheel has the needed power and signal sources. I used F26 for the ignition source and F11 for the light switch signal. See Figure 5.

 

14. I decided to mount the pressure gauge just to the right of the side mirror control ****. This is NOT a good location for easily viewing the gauge while driving because the turn signal stalk blocks the gauge from view. However, you can lean forward and easily see the gauge. I chose to use this location because the gauge could easily be mounted there without any permanent modifications to the interior of the vehicle (and it was quite easy). See Figures 6 and 7.
15. Reconnect the battery ground cable.
16. Check for oil leaks.
17. The gauge has an adjustable feature that allows the user to set a low pressure value that results in flashing of the pressure reading. The factory Discovery warning light comes on between 3.5 and 6 psi.

 

What part number was the Tee fitting and was this purchased at ACE? The Tee fitting is 1/8 on both ends and M12 by 1.5 in the middle?

Could you not have removed the plug above the pressure switch and have used that hole for a pressure reading?

 

Wow. You dug up an old thread! I drilled and tapped the middle port on the tee to work with the m12 x 1.5 adapter. I couldn't find a 1/8 npt adapter, so that was the only way I could do it.

Not sure about the other port.

 

Yeah, I am hooking up an aftermarket gauge and am having problems finding those special conversion fittings, specialy to do the Tee set up. So I decided to look around the engine for another option. I spoke to a few land rover experets about using the port above the pressure switch, and they told me that it can be used. This port was being used on the O2 and down to run an oil cooler, but on these vehicles O3, O4 it was removed.

 

Hello
My oil light comes on, and my oil and filter are clean, checked dip stick and oil is full and splashes up the dip stick. Could my oil pressure switch be the problem?
2001 discovery.thanks.

 

Whoa, quite a jump there vandshome - have you installed an after market oil gauge, or just wondering about your oil light being on?

If just factory stock - oil light comes on about 7 PSI. It should come on when truck is cranked and go out in a couple of seconds. Normal PSI running 2000 rpm is like 40 PSI in a D1 and higher in a D2. So don't be driving to the parts store in this truck.

The oil pressure switch can go bad, it is cheap and easy to unscrew and screw in a new one. That would be a first step. If you heard any strange noises, like tapping, clattering, etc., might want to borrow an oil pressure test gauge from the auto parts store and screw it in where the switch goes. Need 10 PSI or better at idle and 40 PSI at 2000 - 2500 RPM for a D1 and 50 PSI for a D2. Other wise, your oil pump could be bad, they crack and make some, but not enough PSI.

This is a serious don't drive the truck issue if the switch is OK. And it is always a good time to check oil pressure.

 

Just ordered my gauges from glowshift. Oil pressure, water temp and volt meter.

Pics to follow.

 

I seem to not be able to find the oil pressure switch.
Is it above the oil filter?

 

Yes. On the passenger side of the vehicle. It bolts into front engine cover.