Any hints?

"VincentMalamute-Kim" (VincentMalamute-Kim) 07/26/2015 at 23:44 • Filed to: None

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1998 Subaru Forester. I’m changing out both O2 sensors to clear a CEL. I assume they’ve never been changed in the car’s 146,000 miles and 17 years in Wisconsin salt. They feel stuck on there solid. I feel I’m pretty darn good with getting rusted out bolts out - PB Blaster, hammering, vibration, air hammers, tighten first and my trusty last resort - oxy/acet heat to red hot.

Currently I’m leaving the PB Blaster to soak in overnight. But tomorrow:

Question 1 - would oxy/acet heat help in this case? I’m questioning this because these things are getting heated pretty close to red heat during regular operation anyways. But then I’d be heating the O2 sensor to red hot only - not the pipe - differential heating and expansion.

Question 2 - I’m thinking of cutting the wires to get a regular deep socket on there instead of the weak O2 socket with the slit cut out for the wire. But then I’m committed to getting the O2 sensor out of there. Would you guys do this?

Anything else?

Arben72 > VincentMalamute-Kim 07/26/2015 at 23:51

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Fire is fine, I had to use it on my old O2 on my forester. Probably destroyed the sensor but I was replacing it anyways. Impact made it easy after that. I used a normal autozone O2 socket.

PowderHound > VincentMalamute-Kim 07/26/2015 at 23:53

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Vice grips and rubber mallet?

VincentMalamute-Kim > PowderHound 07/26/2015 at 23:55

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Haven’t stripped it yet - so the O2 socket still works. I’ve been hammering it with a regular hammer for the vibration. I think fire it is tomorrow.

AMGtech - now with more recalls! > VincentMalamute-Kim 07/27/2015 at 00:07

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Heat makes things expand, right? So heat the pipe, not the sensor. Put a pipe over your ratchet, or use a longer ratchet if you need to.

Gripevo1 > VincentMalamute-Kim 07/27/2015 at 00:09

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The heat should help...also like you said try cutting the wires and using a deep socket and a large breaker bar. Usually works for me.

Autofixation > VincentMalamute-Kim 07/27/2015 at 00:30

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I say you cut the wires, put a socket on them, and heat always helps.

Jayhawk Jake > VincentMalamute-Kim 07/27/2015 at 01:10

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Heat does wonders. I swapped my downpipe today, came home from a drive and loosened the sensor before the exhaust cooled down.

You can get a socket for O2 sensors specifically. Has a slot on the side for the wire. Of course if you have a new one ready there’s nothing wrong with cutting the wire

desertdog5051 > PowderHound 07/27/2015 at 02:07

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Splittin’ hairs here.

“Everyone has at least one vice. I know I have several. On the other hand, a vise is a handy tool to have”.

pip bip - choose Corrour > VincentMalamute-Kim 07/27/2015 at 03:54

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subaru upper engine cleaner will loosen anything rusted on

FlimFlamMan > VincentMalamute-Kim 07/27/2015 at 08:05

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It’s gotta come out. I would snip the wire and take an impact and/or breaker bar to it. Keep soaking with PB.

VincentMalamute-Kim > pip bip - choose Corrour 07/27/2015 at 11:34

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They make cleaners for the middle and lower engine too?

VincentMalamute-Kim > AMGtech - now with more recalls! 07/27/2015 at 11:53

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I know you’re a pro and I’m a home hobbyist but my understanding of using heat was primarily expansion and contraction of the seized part - breaking the rust bonds.

For example I’ve gotten a lot of seized bolts out of aluminum blocks by heating the bolt. I would think it would be very difficult to heat the block enough given the high heat sinking of an aluminum block and I even if I had enough heat I wouldn’t be able to tell if it got hot enough without melting it since aluminum doesn’t undergo color changes until it melts.

Yes, heat expands things but if you heat the metal, my intuitive understanding is that the hole would get smaller. Other than freezing the metal, you could not get the hole to become larger.

Have you learned more science rather just my crude internet understanding about how breaking loose rust works?

brianbrannon > VincentMalamute-Kim 07/27/2015 at 12:57

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What code are you trying to fix? Both oxygen sensors set different codes

VincentMalamute-Kim > brianbrannon 07/27/2015 at 13:24

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It is the first bank O2 sensor code - don’t remember, P0133?? something like that? I figured I’d change both sensors since 140K+ miles. I’m starting with the second sensor since the first one looks much harder to reach.

And because previous owners didn’t do any maintenance on it. I did head gaskets, rear wheel bearing, clutch, windshield, cat, front CV boots, all 4 struts, all 4 brakes, fuel filler neck, tires after I bought it. Struts/springs are slightly lowering from Primitive Racing so that really improved handling.

I still have a P0400 EGR Flow, an Airbag light that’s on, and something that shuts off the gas nozzle every 2 seconds when I try to fill up.

I bought it as a learning experience on fixing cars and it’s definitely been that. I paid $475 for it which would not have been worth it from a price viewpoint.

AMGtech - now with more recalls! > VincentMalamute-Kim 07/27/2015 at 16:03

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I don’t know about the actual science behind it all. However there was an experiment we did back in 7th grade with a hole in a piece of steel and a steel ball that was too big to fit through said hole until the metal piece was heated. Once it cooled the ball wouldn’t fit any longer.

That and I grew up in Minnesota and worked in my fair share of shops there. Middle of nowhere shops that occasionally would see 60-70 year old farm trucks that were still used for work.

Heating the sensor will more than likely work, for the same reasons you cited. But in my experience it works better to not heat the seized component and instead heat what it is seized into. Keep in mind that heating the sensor might destroy it, worse than cutting it’s wires would.

VincentMalamute-Kim > AMGtech - now with more recalls! 07/27/2015 at 19:34

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Thanks. It would be nice to know the science of things. But the empirical evidence you describe is good enough for me.

MM54 > VincentMalamute-Kim 07/27/2015 at 19:40

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I tried to get mine out (2002 crown vic, spent its whole life in the salty northeast) and couldn’t (I don’t have torches nor would I trust myself with them in the tight confines where my o2s are) and took it to my mechanic - he basically said that he could get them out, but they’re bringing the threads out of the bung with them, and there’s not enough metal left to weld in new bungs.

If you’re at the same point, you may be looking at, at minimum, a few new inches of exhaust clamped in (cheap temporary fix) or a new exhaust (long term).

MM54 > AMGtech - now with more recalls! 07/27/2015 at 19:41

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I’ll second your observations - I’ve put valve seats in small engines by soaking them in liquid nitrogen and heating the head. They drop right into place and, once the temps return to normal, are very well set.

AMGtech - now with more recalls! > VincentMalamute-Kim 07/27/2015 at 21:21

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Agreed.

AMGtech - now with more recalls! > MM54 07/27/2015 at 21:22

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I like the nitro idea a lot. Normally people just put the head in an oven for a while.

VincentMalamute-Kim > VincentMalamute-Kim 07/27/2015 at 22:17

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You are correct. Maybe the more accurate statement is “your method worked”. I heated up the sensor to red hot - no go with the O2 sensor socket. I clipped the wires. Then had to cut off the sensor (PITA with the sawzall since the die grinder wouldn’t fit) because the 22mm deep socket wouldn’t go far enough.

I got the bung red hot (the sensor was red hot too), put the socket on and it started rotating fairly easily. As everything cooled down, it got harder and harder to turn.

I’m going to drop the exhaust manifolds and pipe ahead of the cat to get O2 sensor No. 1 out. Then I’ll be able to get a die grinder on the sensor.

VincentMalamute-Kim > MM54 07/27/2015 at 22:20

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I just got out Sensor No. I heated up the sensor to red hot - no go with the O2 sensor socket. I clipped the wires. Then had to cut off the sensor (PITA with the sawzall since the die grinder wouldn’t fit) because the 22mm deep socket wouldn’t go far enough.

I got the bung red hot (the sensor was red hot too), put the socket on and it started rotating fairly easily. As everything cooled down, it got harder and harder to turn.

I’m going to drop the exhaust manifolds and pipe ahead of the cat to get O2 sensor No. 1 out. Then I’ll be able to get a die grinder on the sensor. AMGtech was correct - heat up the metal around the sensor if you can.

I haven’t checked yet to see if the threads stayed behind with the bung - I assume it did.

VincentMalamute-Kim > Arben72 07/27/2015 at 22:22

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See my response to AMGTech. You’re lucky. I was overimagining things I’m sure but I swear I could feel the split style O2 sensor socket starting to spread on my long breaker bar

MM54 > VincentMalamute-Kim 07/27/2015 at 22:23

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This is why I’ve been driving slightly-rich on lazy O2 sensors for two years :)

VincentMalamute-Kim > Autofixation 07/27/2015 at 22:24

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See my response to AMGTech. I also had to cut the sensor body off to get the deep socket on. This is a PITA. O2 sensor 1 will be tomorrow but I’m going to drop the exhaust manifolds and pipe first.

VincentMalamute-Kim > FlimFlamMan 07/27/2015 at 22:24

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See my response to AMGTech. I also had to cut the sensor body off to get the deep socket on. This is a PITA. O2 sensor 1 will be tomorrow but I’m going to drop the exhaust manifolds and pipe first.

VincentMalamute-Kim > MM54 07/27/2015 at 22:27

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I hate having lights on in the dash - OCD. And I’m out of black tape. If you were near Milwaukee I’d help you change yours - after I get sensor 1 out, I will be an official certified sensor remover.

pip bip - choose Corrour > VincentMalamute-Kim 07/28/2015 at 03:25

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not that i’m aware of.

MM54 > VincentMalamute-Kim 07/28/2015 at 07:38

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My CEL bulb burned out, and when I pulled the whole cluster out to replace all the other bulbs, I conviniently forgot about that one :)

I have a code reader, so I just scan every now and then (or if something feels off) to check for anything new.

brianbrannon > VincentMalamute-Kim 07/28/2015 at 10:12

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The rear one doesn’t effect the running of the car at all. The car also uses the front sensor to diagnose the EGR system so it may be related

VincentMalamute-Kim > brianbrannon 07/28/2015 at 10:30

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oh. Let me think about this. The first one is used to send air/fuel ratio corrections to the ECU and the second one tells the ECU that the cat is working?

brianbrannon > VincentMalamute-Kim 07/30/2015 at 14:45

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Correct

VincentMalamute-Kim > brianbrannon 07/30/2015 at 16:04

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Thanks!