smithk993

I'm swapping out my exhaust and will be reusing the O2 sensors. Is it OK to spray some penetrating oil to help with removal. I know it shouldn't get on the tip but should it cause any issues otherwise?

Thanks.

Keith

Macster

My understanding is that whatever fluid or thread lube is used on the sensor must be O2 sensor compatible for the fluid or lube will migrate to the tip and contaminate it. This is why for even thread lube silicon free lube be used, for over time some of this will work its way towards the tip end and in the heat of the exhaust form deposits on the tip which would affect it if the wrong thread lube used.

I am not sure if you use penatrating oil and even if none gets on the tip during dissassembly there is any cleaner you can use to remove any traces of oil and that won't leave any residue on the tip.

Also, even if you're successful in removing all traces of the oil and the tip is left unaffected after the cleaning the sensor threads in the exhaust system need to be thorougly cleaned too. This complicated by the fact the threads are through into the exhaust system so some oil and cleaner will be inside and around the hole to effect contamination sensor tip after the clean but old or even new sensor installed.

If you manage to get the sensor clean without knowingly or even unknowingly damaging it, and you manage to remove all traces of the oil and any sensor thread lube from the mating threads in the exhaust system, you must then treat the old sensor with its clean dry threads with some approved sensor thread lube to help prevent thread seizure occuring.

Are you sure the sensors need penatrating fluid treatment? Have you tried to remove them with everything cold? Be sure -- it can get a might confusing -- when you are under the car you are turning the sensor in the correct direction to unloosen it.

Not all cars are the same, but when I went to remove a bad sensor in my 02 Boxster at around the 80K mile mark and some of those miles accumulated driving in driving rain, even snow and ice on saltes/gritted roads, the sensor came out without any drama. It was not "that" tight and I saw no evidence of any thread corrosion.

In short, I would avoid applying anything to the sensors with the intent of facilitating their removal unless absolutely necessary. And unless you can find a suitable cleaning fluid discarding the oil contaminated sensors for new ones.

You are still faced with the task of cleaning the exhaust system so there is no chance of any residual oil or whatever contaminating the new sensor.

Sincerely,

Macster.

smithk993

I will give a try before I use anything.

Also should I unhook the O2 sensors in the engine compartment and then drop the muffler or is there enough slack to drop the muffler and then remove the o2 sensor from the muffler?

Keith

Macster

Disconnect each O2 sensor at where it connects to the wiring harness.

Wrap a clean plastic baggie around the sensor connector free end and tape or rubber band the baggie in place. You do not want to get dirt or grease or oily stuff in this connector. The connectors in the car should be ok unless your crazy wild clumsy.

Then loosen and remove the sensors and set them someplace where they won't be disturbed, either on purpose or accidently, and are not going to get anything on them - dust, dirt, cat hair, an inquisitive kid's fingerprint -- while their sensitive tips exposed.

Now you can remove the exhaust system cause you will not have to worry about the connector wiring hanging up -- which can cause the exhaust system to slip from your grasp and fall to the floor with disasterous results -- or the risk of banging a delicate sensor as you move the exhaust system around as you work to get it out from under the car.

Assembly is the reverse of dissassembly.

Sincerely,

Macster.

smithk993

Well I figured out the tricks to unhooking the sensor wiring up in the engine compartment. I love how they use two different connectors and clips on the plugs. There seems to be a couple of wiring harness clips or something that are not reachable however. Not sure if it will allow me to drop the exhaust until I figure out how to unhook wiring from these. Also I cant get my 22mm open end wrench on the sensors until the muffler is dropped.

Keith

daking

Some times is not so easy disassemble o2 sensors. You have to heat exhaust with flame around the sensor (not the sensor).
When you reinstall o2 sensors in your new exhaust remember to put "copper" grease on thread. The grease code is 000 043 207 07.

dantzig

It is possible to lower the exhaust enough to make it possible to get to the O2 sensors with an open end. However, you can also get them out using an O2 sensor wrench kit, available at Autozone. I've done it both ways.

Jon

Mikelly

I've swapped in 5 exhausts, always using the same sensors in the process... This is what I do:

Disconnect the wires on the rear deck next to the motor mounts and feed them down thru the engine compartment to the exhaust...

Unbolt the heat shields, and the exhaust flange bolts from the turbo.

I'd put penetrating oil on those studs for the headers, but not on the 02sensors...

Unbolt the straps and lower the exhaust... it's large, combersom and not easy to hold. I recommend a second set of hands so you don't damage the cables for the 02 sensors by snagging them on the motor.

Lower the system and unbolt the 02 sensors (do not get them confused) using a 7/8th inch wrench or you can buy an 02 sensor socket that can be baught at any autoparts store. I recommend removing one, placing it in the same spot on the new system, then moving onto the next...

Anit-seize is the only thing I use on the threads, and ONLY on the threads.

Mike

SH || NC

I used some PB Blaster before I removed mine and suffered no ill effects. No worries.