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Old 02-25-2014, 03:40 PM   #1
Junior Member
Join Date: Dec 2011
Location: Liberty Hill, TX
Posts: 16
How To - Install an Oil Sensor in the OFAC

This thread will cover the process to install an oil sensor in the GTO's factory Oil Filter Adapter Cap (OFAC).

1. Jack up the car and support it with jack stands

2. Locate the OFAC, and the 2 10mm nuts securing it

The oil filter is removed in these pictures for easier viewing

OFAC 10mm Retaining nuts

3. Remove the OFAC

Remove the nuts, as well as the OFAC and the gasket. When removing the OFAC, a small amount of oil will drain, so position a catch pan, or some rags appropriately. I took this opportunity to change the oil as well.

OFAC removed

OFAC, nuts, and factory gasket

4. Drill and tap the OFAC

Next, you will drill a hole in the OFAC and cut threads in it with a tap

4.1 Locate, or purchase, a Q sized drill bit and a 1/8" - 27 NPT tap

I used
this drill bit this drill bit
I purchased from Amazon

Q sized drill bit

and I used
this 1/8"-27 tap this 1/8"-27 tap
I also purchased from Amazon

1/8"-27 NPT tap

4.2 Drill the hole

Use a punch to indent the top, center of the OFAC. This will allow the drill bit to get a clean start, then drill a hole through the OFAC. I used a drill press to ensure the hole was straight.

4.3 Cut the threads

Use the tap to cut threads into the hole you just drilled. I recommend you work the tap through the hole, but stop about 3-5 threads from the end of the tap. Since NPT taps are tapered, stopping a few threads from the end will ensure the sensor tightens up.

Drilled and tapped OFAC

Notice my sensor is a bit deeper than the housing

Sensor installed in OFAC

Sensor installed in OFAC 2

If I had stopped the tap 3-5 threads short, like I explained above, I believe the sensor would have tightened up before extending past the OFAC housing. But, even with this bit sticking past, I don't believe it will leak due to both the gasket thickness, and also due to the threads tightening up even if the sensor does hit the oil pan.
5. Install the modified OFAC and sensor

Because the sensor stuck past the housing, I installed the OFAC and tightened up the 10mm bolts with the sensor removed, then installed the sensor afterward. Be sure to use some teflon tape on the sensor threads to ensure a good seal.

OFAC and sensor installed

I did not need to install a 90* elbow, like mentioned in other another thread, as there is plenty of clearance for the sensor to stick straight out. Notice I soldered a connector into the sensor's wires (you can barely see it to the right side of the above pic), to make it easy to install/remove the sensor without twisting the wires or needing to remove the OFAC.

6. Route the wires

Routing the wires behind the alternator is easy enough, and convenient due to me using a hole in the firewall on the driver's side to get the wires into the cabin.

Sensor wire routing

This pic shows the white connector I soldered into the wires more clearly. I know this isn't an automotive weather proof connector, but it's what I had on hand when I did this project. If it gives me problems, I'll replace it with a weather proof connector.

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Old 02-26-2014, 10:55 PM   #2
2QWK4RU 06 GOAT's Avatar
Join Date: Oct 2011
Location: Mexifornia
Posts: 587
Nice job.
"You'll eventually send me your diff, send it the first time, not the second or third time! This will prevent thousands of dollars going to waste." STANDARD LIMITED LIFETIME GUARANTEE IS STANDARD ON ALL BUILDS.

"Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end"
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