Oxygen sensor replacement

[jpdukes]

I'm trying to replace an O2 sensor in a 92 Loyale. It looked pretty straighforward, except the only way I can find to loosen the sensor is with a deep socket (after you cut the wire). Only problem is there's no way to get the socket on the sensor. It gets jammed between the U-Joint and the transmission. You just can't get the right angle.

 

Has anybody done this? The only thing I can think of now is to try and drop the catalytic converter. I can probably manage this, but it's a huge pain--the bolts are so old and seized and I'm not sure which one's it makes sense to loosen. Anybody know another way?

 

 

-JPD

[azsubaru]

First, check out the "Similar Threads" in the lower right hand corner of the screen. You should get some good info there.

 

You need a sensor socket - rent one from Autozone, about 15 bucks, then take it back when you're finished and they'll refund your money.

 

And you really should drop the exhaust. It's only the 4 nuts on the heads, then pull it down, and it becomes an easy job.

 

I have done it without dropping the exhaust, but you run a big risk of stripping the threads in the converter. I've done that, too.

[jpdukes]

Thanks. I remember now that I had to get new threads tapped for those exhaust bolts at the head.

 

When you dropped the exhaust, did you put a new gasket or silicone on the flange? If not, any trouble with exhaust escaping there?

 

And what does an O2 Sensor socket have that a regular deep socket doesn't. Some kind of way to accomodate the wire? Or some kind of cushion?

 

Messing up the threads would be a disaster. Did you have to get a new cat or could you tap some in...

 

Very helpful--so was checking out the older threads.

 

-JPD

[Syonyk]

An O2 sensor socket has a slot cut up one side to let the wire out. If you had a socket you didn't care about, you could make your own by just grinding a gap up one side.

 

I've replaced the O2 sensors in a few EA82s, and I've always had to drop the exhaust system down and pull it out from under the car to do it.

 

Then again, I've never had a Subaru with a complete exhaust system when I replaced the O2 sensors, so... YMMV.

 

-=Russ=-

[azsubaru]

I cut new threads with a spark plug re-threader, thanks to the advice of Northwet here on the board.

 

It worked pretty good, but I still had to drop the exhaust to do it, so I wasted a lot of time on that project.

 

Spray a lot of liquid wrench or something like that on the exhaust studs and let it sit as long as you can. If you don't get too agressive, you should be able to get them off ok.

 

You can most likely re-use the exhuast gaskets if they aren't leaking now.

No need to add anything, just put em on dry. If you do get new gaskets, by the OEM (manufacturer) brand. The after market ones are usually poorly made and won't last long.

 

You shouldn't need anything on the flange, either, it's designed to move around a bit.

[Gloyale]

A large open ended wrench, prefferably one of those funny ones with the parrallel offsets. That's what the FSM shows If you get the old one out clean, no need to drop exhaust or re tap.

 

EDIT: well after further review I guess what the FSM shows is a funky subaru tool, like a bent, box end crows foot thing. Sorry, I've only owned Carbed or Turbo

[Tom63050]

You need a sensor socket - rent one from Autozone, about 15 bucks, then take it back when you're finished and they'll refund your money.

 

And you really should drop the exhaust. It's only the 4 nuts on the heads, then pull it down, and it becomes an easy job.

 

I have done it without dropping the exhaust, but you run a big risk of stripping the threads in the converter. I've done that, too.

 

I got my O2 sensor off with an 8-point 7/8" box wrench (probably 22mm equivalent?). Had to cut the wire anyway to splice in a new one (or you can add male & female connectors). Threaded the wrench down over the wire onto the sensor, then just wrenched it off. Didn't take off the exhaust--don't know why it would be more at risk to strip the threads in the cat if the exhaust is left on. Seemed like an easy job (helps if the vehicle is lifted or on ramps of course).

 

Chase the cat's threads with the appropriate tap, and put some anti-seize on the new sensor's threads before installing it.

[mellow65]

I got my O2 sensor off with an 8-point 7/8" box wrench (probably 22mm equivalent?). Had to cut the wire anyway to splice in a new one (or you can add male & female connectors). Threaded the wrench down over the wire onto the sensor, then just wrenched it off. Didn't take off the exhaust

 

+1 for this route.

 

I ended up buying one of those o2 sensor sockets and it didn't even fit. It was angled at the motor so I couldn't get a socket on it.

 

Just took an regular old wrench and took it off and put the new one on with it.