1989 F250 with the big 460 of course ---

I cannot find the O2 sensor on the exhaust manifold. I looked and looked and looked. Where is it? I want to hear from someone with same 460 truck configuration and year precisely how to replace it -- from which side? Right? Left? From top (i.e. engine bay) Bottom? (i.e. crawling under the truck).

I know how to replace it, I just need to find it.

What compounds my aggravation is that neither Chilton's nor Haynes nor Factory Service Manuals (I have all of them) can point out where it is, just say on the exhaust manifold.

 

It's between the exhaust manifold and the cat. I'd tell you exactly where it is but my exhuast system is no longer "stock". I went to dual exhaust and had the mufler shop cut-out the O2 bung and reweld it to my new system. I kinda remember it being about 2 feet further back from the exhaust manifold...

Deen

 

Yeah, it should be fairly easy to find. Don't know your year but an O2 sensor is pretty big, about the size of your fat middle finger, and it will have 2 or 3 wires coming out of it.

It should be the only thing with wires coming out of it attached to any of your exhaust system(Unless you have an electric manifold heat controller, unusual).

It is usually in the first 2-3 feet of the exhaust tubing. On older models it is usually before the catalytic converter. Some models have 2 or even 4. Older models usually have only 1 or 2 depending on whether you have true dual exhaust.

It might be hidden by heat shielding or may be inside of some fiberglass woven tubing. It is usually accessible since it is a routine tune up item.

Usually it sticks straight out from the exhaust tubing.

It is often a beach to remove. Get the right tool and use some penetrant. I use a horking big open end wrench but they also sell special sockets.

When you replace it use some antisieze(often they already have some gooped on).

Good Luck,

Jim Henderson

 

I found it!!!

It is 2 ft in front of the catalytic converter. And I spent an hour looking around the engine, on both exhaust manifolds. The FSM -- 1989 engine emissions manual was misleading BTW.

Every maker places them in a different spot. When I replaced mine on Chebby, it was accessible through the engine bay, so that gave me that idea. On the Subaru, it is where the 2 Y-pipes join into one. But on 89 F250, it is way back there.

I sprayed it with PB Blaster. When the new O2 sensor gets here, it should be ready to remove. I already have the deep 7/8 socket, but will have to have some kind of bent (curved) open end wrench for putting the new one in. I don't really trust that special O2 sensor tool at auto parts places - the last time I was using in, I bent it during removal. Though it might be useful for installing the new sensor in there if you don't put too much pressure on it.

 

The new sensor should come with anti seize on the threads. It should go in almost all the way by hand the last turn or so can be with an end wrench. They don't have to be super tight... Just enough to compress the washer/seal. Be careful with the wire or wires... I can't remember if 89 had a multiple wire sensor or not. If I remember right the hardest part on the last one I did was getting the wire plugged back in. I had to get my son/assistant to reach up with his smaller arms to get it.

 

haven't replaced it yet, but from a brief look, it seemed to be a single-wire sensor (Unheated as far as I know)

 

only a 1 wire????????, my 88 E-350 460 engine had a 3 wire O2 setup on it........ that's weird