While trying to diagnose the ’Murlequin’s idle issue, one of the possibilities on my list was an oxygen sensor. That wasn’t the problem, and it wasn’t even tripping any codes, but I figured it was probably starting to get dirty anyway, and could stand a good cleaning. It had certainly been been on there a LONG time, and wasn’t going to come out easily...

It’s nice to finally be caught up on necessary repairs, so I can focus on small annoyances and preventative maintenance. I was considering cleaning the oxygen sensor, but it was starting to look like removal might damage it. Besides, a new one was more affordable than I expected, so I just bought one and got to work trying to remove the (1995 original?) sensor.

I couldn’t tell where the Y-pipe’s bung ended and where the sensor began. It looked like one rusty (welded? I hope not) piece. I tried brushing the rust away, but this did not reveal the seam. So I soaked it in penetrating oil and and continued driving the truck for a few more days to put it through a few more heat cycles, soaking the bung with more oil between drives.

Please don’t be welded. Please don’t be welded. Please don’t be welded.

Having done my best to prep it, I crawled underneath and braced my feet against the frame. There wasn’t room for a socket, nor was I about to try an open-end wrench. Instead of cutting the wires and slipping a box wrench over it, I got a pipe wrench and pulled as hard as I could.

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Nothing. It was rusted on there something fierce. Maybe I should just leave it alone. After all, if it ain’t broke...

No, wait! If I could just get the truck where I could stand up underneath it, I could really put my body weight into it. Something’s gotta give, right? Either that sensor is going to unscrew, or the threaded bung is going to tear right out of the pipe. Both options seems equally likely...

A friend had a car hoist that he built himself in his pole barn. This is the same hoist that he kindly let me use for a clutch job on one car, and a transmission job on another.

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If he’s up for it, maybe I’ll get him to share the process of building it. It’s just like a two-post lift, except that it’s made from two forklift masts, placed about 9-10 feet apart and anchored securely in concrete. A bank of car batteries drives the hydraulic motor, and either mast can be operated independently, or both at the same time. Two arms from each mast swing underneath the frame and extend to the vehicle’s jacking points. Once at the desired height, heavy blocks rotate into place to lock it from falling down. For added safety, a couple of nearby extra-tall jackstands can be placed under the vehicle.

I lifted the truck, took my pipe wrench underneath, and quickly learned that leaning into it wasn’t going to be enough. So I extended the handle with a piece of thick square steel tubing and a crowbar. I started to pull and soon heard a *CRACK*. Small flakes of oxidized metal had broken away to reveal a thin line between the sensor housing and the bung. Yes! Soon, I was able to set the “extensions” aside and wrench the sensor out, leaving the pipe intact.

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LEFT: MOAR leverage. CENTER: Finally cracked loose. RIGHT: Chasing threads.

I cleaned up the threads in the bung, and applied anti-seize to the threads of the new sensor, being careful not to contaminate the element. I wrenched it on, connected the harness, and before i knew it, it was time to lower the truck back down.

LEFT: Old sensor vs new. RIGHT: Dear anti-seize, I love you.

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That was it. Piece o’ cake. All too easy. It happened so fast, I didn’t even feel ready to come out from underneath the truck, but I didn’t have any other work that needed to be done that day. So I lingered for a minute anyway; it’s so much easier to inspect things when you can walk around instead of rolling around on a creeper. Man, I’d love to have a hoist like this in my garage.