TheSamba.com :: View topic - Rusted Frozen Stuck O2 Sensor From Hell

Thu May 07, 2015 8:31 pm

So....a friend has an 87 Westy with the 2.1 that has been running terribly. Hunting idle, sooty exhaust, and terrible fuel mileage. I decided to help him replace his O2 sensor. He has owned the van for 15 years and never replaced the sensor. I started with spraying it down with penetrating oil the day before we were going to replace it. Of course with my luck there is no easy fix. EVER!!!!

The O2 sensor would not budge. 24 hours of spraying with PB Blaster and the sensor would not budge. I jumped on the Samba and started the search. Whats the best way to remove a frozen or stuck or rusted O2 sensor? Nothing! Really? Nothing! I did a broad search on O2 sensor and pieced together some information and techniques. That's why I am writing this post. Lets put it all in one place Samba.

This is my story of how I got the O2 sensor from Hell out of the cat converter. Please provide your input and stories so that future searchers will find this post and know that there is hope for getting these rusted in sensors out.

1- I did find in a buried post that it is best to start spraying the frozen sensor with a penetrating oil 2 days before trying to remove it. It takes time for the oil to work.

2- Tap on the sensor with a brass hammer to try and jar the corrosion and break it up between the threads. Spray with the penetrating oil and tap it with a brass hammer. Don't mangle the sensor with a steel hammer. You wont be able to get a wrench on it.

3- Get the right size wrench. All I had was a 7/8. A 22mm box wrench would have been perfect.

4- Heat. I tried to use a propane torch to heat the sensor to try to break up the frozen threads. No Go. I stepped it up to a Mapp gas/Oxygen torch. I heated the sensor until it was glowing red.

None of these worked for me. I ended up rounding off the sensor and had to resort to a pipe wrench. I wrenched on it until I stripped of the head of the sensor. Now I only had the threads stuck in the Cat. All the ceramic insulation inside of the sensor crumbled out of what was left. There is a hole in the middle of the sensor that is about 5/16". I ended up driving a #10 Spline Bit into the remaining sensor and putting a 1/2 ratchet on it. It still took a breaking bar to get enough leverage on it to pop loose.

Here is the carnage:

The threads on the O2 sensor are the same threads as a spark plug. I reset the threads in the Cat with a spark plug die. Stripping the threads after so much work to get the old one out would have sent me over the edge.

Post your technique if you have one. I could have used a better method. Not sure if more penetrating oil would have done it or if I heated it up to hot. Anyway, the #10 spline bit did the trick!

BTW the van idled down and loves the new O2 sensor. Cheers Samba!

Thu May 07, 2015 8:51 pm

penetrating oil works over time - spray, tap every hour for a week

not sure why the torch didn't work

Thu May 07, 2015 9:13 pm

It is just a matter of out stubborning the O2 sensor. Nice work! Love your resilience.

Thu May 07, 2015 9:24 pm

Unfortunately, since I live in the desert s.w. I have zero experience with rusted-in fasteners, and I feel real deprived for not having knowledge of that fun, BUT... I've read that tightening just a smidge helps too.

Thu May 07, 2015 9:53 pm

Nice! Out stubborn-ed it, eh? Heh, perfect term for that. Must have felt pretty good to hear/feel that thing suddenly break loose, eh?

Doug

Thu May 07, 2015 9:59 pm

I've on occasion clipped the old O2s wire short. and welded in a new bung in a nearby easy to access section of the pipe.. call the OEM one a "test plug"
new bung holes are only a couple bucks, and not worth more than an hour of my life trying to out stubborn some dead O2.

once I realized the problem was how to put the NEW O2 in...
not how to fight to get the old O2 out. (if it won't come w/traditional heat/oils/leverage)

Thu May 07, 2015 10:00 pm

IdahoDoug wrote: Nice! Out stubborn-ed it, eh? Heh, perfect term for that. Must have felt pretty good to hear/feel that thing suddenly break loose, eh?

Doug

Man was it ever! That spline bit only grabs hold of so much. I was afraid I was going to wrench out the spline bit and strip what was left of the sensor. You know the feeling of when the bolt or nut finally pops loose. You don't even have to look at it. It was the best squeaking gritty popping feeling a guy can have with his exhaust system. :oops:

Thu May 07, 2015 10:00 pm

i am considering the lazy route: http://www.van-cafe.com/home/van/page_385_277/collector-pipe-1.9-liter.html

Thu May 07, 2015 10:04 pm

atomatom wrote: i am considering the lazy route: http://www.van-cafe.com/home/van/page_385_277/collector-pipe-1.9-liter.html

FYI, I went this route with my suby swap. The O2 sensor was so close to the exhaust gas directly off the manifold that every time I drove up a grade the O2 sensor would get so hot that it would throw the O2 code. As soon as it cooled off the computer would reset and it was ok. I had to plug the O2 hole and drill my cat. Once I relocated it into my cat the O2 works great. No hot sensor failure.

Fri May 08, 2015 5:57 am

Wouldn't heating the sensor cause it to expand and be more tightly stuck in the bung? I would try heating the metal around where the O2 screws in to expand that. I've read you can also run the motor for a short while to accomplish the same thing.

And an 50/50 mix of ATF and acetone works the best as a penetrating oil. I used it a couple days in advance on my radius rod and nuts, which had seen 24 New England winters, and they turned without giving any real fight.

Fri May 08, 2015 6:13 am

That's odd as in the 1.8T we have an O2 right near the turbo. if that doesn't get screamin hot.. in the 5cyls they mount them into the exhaust header (same for many I4s as well, right into the header.
AKWesty wrote:
FYI, I went this route with my suby swap. The O2 sensor was so close to the exhaust gas directly off the manifold that every time I drove up a grade the O2 sensor would get so hot that it would throw the O2 code. As soon as it cooled off the computer would reset and it was ok. I had to plug the O2 hole and drill my cat. Once I relocated it into my cat the O2 works great. No hot sensor failure.

Fri May 08, 2015 7:33 am

Heat up the bung, melt candle wax into the threads, repeat until it screws out.

Dave

Fri May 08, 2015 7:51 am

Here is main reason he had a hell of a time yanking the sensor;

"Heat. I tried to use a propane torch to heat the sensor to try to break up the frozen threads"

Exactly opposite of what was supposed to be done.
Heat the bung up cherry red , not the sensor.
He made the situation worse by getting it hot, not the pipe.

Plus propane is like being stuck in the mud without 4wd, on bald tires--it ain't gonna happen.

Fri May 08, 2015 9:16 am

Dang it. Leave it to me to botch this part of the job. I can never remember if you heat the bolt or the bung in a situation like this. Look like I choose the wrong one. EXACTLY why I put this thread together. Hopefully the next guy wont make the same mistake.

Fri May 08, 2015 9:22 am

danfromsyr wrote: That's odd as in the 1.8T we have an O2 right near the turbo. if that doesn't get screamin hot.. in the 5cyls they mount them into the exhaust header (same for many I4s as well, right into the header.
AKWesty wrote:
FYI, I went this route with my suby swap. The O2 sensor was so close to the exhaust gas directly off the manifold that every time I drove up a grade the O2 sensor would get so hot that it would throw the O2 code. As soon as it cooled off the computer would reset and it was ok. I had to plug the O2 hole and drill my cat. Once I relocated it into my cat the O2 works great. No hot sensor failure.

It surprised me that the brand new O2 sensor mounted in the connecting pipe would throw the O2 code when it got hot. I drove it for a week with it mounted close to the header. Every time I drove up the same steep grade the O2 light would go off. I just assumed that it was to close to the heat and needed moved back in the exhaust system. Anyway I moved it to the cat and no more problem. Maybe it was something else. Sounds like if you can mount them next to the turbo that heat should not be a problem.

Fri May 08, 2015 11:24 am

AKWesty wrote: Dang it. Leave it to me to botch this part of the job. I can never remember if you heat the bolt or the bung in a situation like this. Look like I choose the wrong one. EXACTLY why I put this thread together. Hopefully the next guy wont make the same mistake.

probably me...just got mine in and need to replace it. I'm sure to strip and or break something that will leave me scratching my head all weekend.

i do have a torch...now i know what not to do.