Adding an Electric Oil Pressure Gauge
By: Bob_98SR5
Written: 11/24/04
Application: 1998 4Runner V6



Parts

Autometer Z-Series Electrical Gauge (#2634- includes electrical sender)
1/8" female to 3/8" male adapter
Lo-tek gauge pod (optional, but have a mounting option available)

Tools & Supplies
Adjustable-head rachet with a variety of metric and SAE sockets
Various short and long rachet extensions
Crow's foot wrenches (rachet head)
Crescent wrench
18 gauge positive and negative wire
Ring connectors
Soldering iron and solder
Heat shrink tubing and matches
PB Blaster (Liquid Wrench or Tabasco sauce)
P-Touch label maker
Zip ties
Teflon tape
Eye protection


Disclaimer

I am providing this write up for illustrative purposes only. Perform at your own risk. Any mods (including this one) you perform on your vehicle is your responsibility. Commercial use of this write up may result in legal action.


Addendum - November 28, 2004
I discovered that I had a very small leak coming from the oil pressure port. It was a major pain in the ass to diagnose and fix---mainly because there is hardly any hand space in there. Of the major changes to this writeup, I had to remove the sender from the 1/8" female to 3/8" male adapter, teflon tape the threads on the adapter and sender and *then* put it all back on. But there's an order you should follow to make sure everything is leak proof. Read on.

Summary

I plan to install a Permacool oil filter relocator kit in the near future and thus, I decided to add an aftermarket oil pressure gauge to monitor the oil pressure. I installed this first because I wanted to understand what the stock oil pressure is and then use the data to make sure that the Permacool kit had no adverse effect on the oil pressure.

As is the case, this writeup borrows heavily from available resources and previous installs. Special thanks goes out to Jsharp (Jim). Jim's advice via email and PMs were invaluable to this mod as well as (and especially) the Permacool oil filter relocator mod. Jim, much appreciated! Also, I used Gadget's excellent gauge page as a reference as well.


Step 1: Prep Work

As always when doing electrical work, unhook your negative battery cable. Next, remove the skid plate by removing the seven 12mm bolts. You may need an extension to access all the bolts. After removing the skid plate, spray a generous amount of PB Blaster onto the 8mm allen key plug as shown in the picture below. After about 15 or 30 minutes, spray it again. What I did was to spray it a few times and let it soak overnight.

  
Remove the seven 12mm bolts (B) from the skid plate to remove   You are looking at the oil filter and pump area as seen through the left front wheelwell. Spray the rusted 8mm plug (A2) with PB Blaster. (A1) is the plug to the oil pump discharge port and (S) is the stock low oil pressure sender

Now would also be a good time to unbolt some interior panels:

  
Remove the four 10mm bolts   After removing the lower panel, pop out piece (B) and unscrew four screws securing door sill panel (C)

Step 2: Removing the Extra Oil Port Plug
Take your adjustable head rachet wrench with a short adapter and a 8mm allen key and remove the oil plug. The way I got it out was to manuever the wrench up and around the front part of the oil pan. Buy using the adjustable head wrench, you can move the shaft of the wrench to have enough room to take off that plug.

     
Tight space: Use an adjustable head rachet wrench with a short adapter and a 8mm allen wrench key. Note: the plug is at the end of the 8mm key   As you can see from this pic, I manuevered the wrench just right in front of the oil pan and fitted the 8mm key onto the plug itself. As you can also see, there is enough room from left to right to get some good action   Here's a pic of the plug

Step 3: Installing the Electric Oil Pressure Sender
Wind around two to three wraps of teflon tape around the 1/8" to 3/8" adapter and then hand screw it into the oil pressure port. Next, use a rachet wrench with a crow's foot wrench (sorry guys, I forgot the size) and tighten down this adapter. It is very important that you tighten this down really good or else you will pull your hair out doing this over again (like I did)!

Now take the sender and put some teflon tape on the sender threads and then hand screw it into the adapter. Take your crow's foot wrench and tighten the sender down into the adapter. This will be a bit more difficult because of the lack of space that's been taken up by the adapter.

Next, starting from the middle of your dash area, run a length of 18 gauge wire down between the A-pillar and the dash, through the interior firewall, into the engine bay and down to the oil pressure sender. Cut, strip and crimp a ring connector on this end.

At the other end of the wire, cut, strip and crimp a ring connector to the end of the wire and slip that end onto the oil pressure sender's terminal. Finally, re-orient the ring connector so it is in a good, non-stressed position and then tighten it down.

I would highly recommend that you label this and all other wires so as not to confuse them. That is why I recommend that you use a P-touch label machine. Also when using teflon tape, start a thread or two down so as not to risk clogging the flow of oil.

  
Here's the electric oil pressure sender and the 1/8th to 3/8th adapter. Note that the adapter is NOT included with the Autometer kit.   Here's a pic of where to run the wire


Step 4: Hooking Up the Ignition, Ground, and Light Wires

For the ignition wire, run a wire down from the dash area to the ignition harness. Attach a T-tap and tap the 12v ignition power wire. Cut, strip and crimp the wire and attach a blade type connector to it and then connect it to the T-tap. For my 98 4runner, the ignition wire was black with red. Yours may be different, so definitely consult a wiring chart. I used the wiring chart engine found on the12volt.com. After doing this, cut, strip and crimp a ring connector to the other end of the wire.

Follow the same procedure for the illumination wire. For the positive illumination wire, you'll need to solder a wire to it and heat shrink the connection point. From there, run that bulb wire from the dash and T-tap it to the green wire that comes from the instrument cluster's dimmer knob/switch. After doing this, cut, strip and crimp a ring connector to the other end of the wire.

  
Tap wire (I). T-tap (A) is for my hardwire Valentine 1 mod   Tap wire (G) for the gauge's light. Ignore (W) and (D)

For the bulb's ground wire, solder/heat shrink the connection and run it to your ground point. Crimp a ring connector to the other end. And lastly for the gauge's ground wire, run it down from the dash area again and to your ground point. Crimp ring connectors to both ends of this wire. Now secure both ground wires to your ground point as shown in the picture below:

  
Not a bad soldering job, eh? :)   Two grounded wires


Step 5: Hooking the Gauge Up
Take your Lo-tek gauge pod and move it into position. Run all the wires through the hole of your choice. You should have exactly 3 wires with ring connectors and the bulb wire with two soldered positive and negative wires. Hopefully you've taken my advice and labeled each wire. For the three wires with ring connectors, loosely tighten them down onto the terminals until final fitting. For the bulb wires, since you've already grounded the ground wire and T-tapped the power wire, you don't need to worry about these two wires.

  
As you can see, I've run all the wires through one of the gauge pod holes   Here are all the terminal points: S is for the sender, (I) is for the Ignition, (G) is for one of the two grounds, (+) is for the light bulb and (-) is for the ground for the light bulb

Now is a good time to test it out before final fitting. Reattach your negative battery cable and start your engine. You should see the gauge needle shoot up to around 75 to 85 psi. If so, turn off your engine and unhook the negative battery cable.

Step 6: Final Steps
Tighten all of the screws down on the back of your gauge as well as re-checking the two ground wires. It's also a good idea to cable tie those five wires into a tight bundle. Do so and then insert/twist the gauge into the gauge pod. Next put the bottom end of the gauge pod in between the existing A-pillar and the dash. Realign it to your liking and then secure the gauge pod with the supplied screws and screw covers. Also, the holes do not line up with the stock grab handle holes. Not to mention, the screw sizes are completely different. Thus, you will have to drill a pilot hole through the existing plastic and metal. Of note, I could not screw in the bottom screw because I did not have a right-angle adapter for my drill. Therefore for the bottom hole, I used some double-sided tape to hold down the gauge pod to the existing A-pillar for a more flush fit. Also, I hot glued the screw cover on because it easily pops out.

Here's the final product pic:

    
Though it doesn't look like it, the gauge pod is about 99% close in color to the stock color. Overall, I'm very pleased.    

Gauge Readings and Opinions
On startup, the oil pressure shoots up to around 85psi. After a few minutes of driving, it settles down to around 50psi. Driving on the streets and on the freeway, it reads between 50psi and 60psi. However at idle after driving a bit, the needle settles around 12 to 15psi.

Of the Autometer gauge kit: I think this is kit provides an outstanding value. The kit comes with the gauge, all the basic screws/hardware, and most importantly, the electric sender. What it doesn't come with is the 1/8" to 3/8" adapter. That only costs change, but this part was not available at Kragen or Autozone and thus, I had to go to a specialty auto parts store.

Of the Lo-tek full A-pillar Gauge Pod: its a great looking piece of plastic! The fit and finish is very good and the paint color is a *very* close match. The only complaint I have is the plastic screw caps. They fall out too easily and that's why I hot glued mine to the end of the screw. Given the fact that these fall out so easily, it would be nice if Lo-tek could include 2 more of these end caps as spares.

Questions or feedback? Email me and I'll try to get back to you. If this article helped you save time, money or just made things more convenient for you, please consider donating to keep this site alive.