I finally got around to (trying) to replace my O2 sensor today. Nightmare!

First, I broke 2 socket wrenches (Harbor Freight) getting the old one out. I finally went to Sears and bought a good socket wrench and eventually got it out by using a huge breaker bar...

Second, the threads are hosed where the o2 sensor was - this was why it was so %*()& hard to get out.

Third, the replacement sensor is too deep for the o2 sensor socket. I was hoping to force new threads with the new sensor. With the sloppy sensor/socket combination, this is not a possibility.

Fourth - my autocross driver's school is Sunday and there are no other classes in the area. I have to have this fixed by sundown tomorrow night or I'm hosed.

Obviously, I am not a happy man.

Here is what I plan to do - Go to the parts store and try to do one of these or all of them:

1) Get a pipe tap to force new threads, then attempt to install the new sensor. If I'm careful, I can probably use the existing socket to install the new sensor. This Assumes that I have reasonable threads.

2) Get a deeper O2 sensor socket.

2) Get a shorter sensor to match the o2 sensor socket

Is there anything else that I can be doing here? It is already dark so I cannot do any work on the car until tomorrow.

Any help would be deeply appreciated. Thanks.

 

Yeah, forget about the O2 sensor socket. Use the old trusty 7/8" wrench. That is what I use and I never had a problem.

If the sensor won't start by hand, don't force it, use the tap to clean out the threads but NEVER force it or else you'll get yourself in deeper.

[This message has been edited by TunedPort350 (edited March 23, 2001).]

 

This has gotten much worse.

I just went to the following stores and I am beginning to think I have a REAL problem now.

I went to:
Advance Auto Parts
Pep Boys
NAPA
Sears
plus two large hardware stores.

Through all of this effort, I have been unable to figure out which tap I need to make the O2 sensor hole correct.

A tap has two dimensions:
1) Diameter
2) count of threads per inch.

It appears that I need about 3/4" for diameter. Does anyone know what thread size I need?

In addition, I can't find a store that'll sell me a single, large tap. I have to buy a whole set - > $100.

HELP!!!!

 

This is gonna sound dumb but...
Take the O2 sensor to the Ace Hardware nut and bolt isle. Find a nut that fits the threads of the O2 sensor. Then find the proper Tap based on the nut.
Easy, huh?

------------------
Rob P
89RSconvtZZ4TPI
Edelbrock Hi-Flow Intake
SLP Dual Cold Air Intake
1 5/8" Headers
Semi-Siamesed Runners
MSD6AL/relocated MAT/ AdjFPR/IROC frnt@rear swaybar/wonderbar/steeringbox/alum drvshaft/ Alston SFC/3:23posi disc rear/MAC LCA/H.Adams Panhard Rod/KYB struts/ shocks/
92Z28convt5spd
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

No it doesn't sound dumb. That's exactly what I did and failed miserably. Like I said, I could pretty much get a 3/4" nut to fit, but the threads were wrong.

The two hardware stores that I said I went to were the private ones (not Lowes, Home Depot, etc.) because I knew I could find that 100 year old guy that knows everything at these stores... Both old timers basically both told me I had a real problem...

Hence the post....

 

Ooopsss.... forgot to mention.

A short replacement O2 sensor doesn't exist and a deeper socket doesn't exist. The recommendation that I could use a regular wrench is a good thought, but I really don't see how to get it where I need it - it's tight in that spot. I had to use an 18" extension on my socket wrench just to make it to this point.

I am now officially desperate.

 

Lay under the car and try, I did this once and it worked well... those manifolds can really be a tight squeeze, so it helps to place the wrench on the socket before you move under the car, then twist it a little and put it on again. I think this is how I loosened it the first time I tried, and finished with the socket. It can be a bitch getting that thing to thread.

 

I will be going to bed soon. Obviously, I will be checking this thread first thing in the morning for more advice.

If I don't see any new advice, here is what I plan to do:

1) Call the local Chevy dealer's parts desk to see if they have any advice. A friend of my dad's works at one of the area Chevy dealers and autocrosses in the same club. Maybe he'll be able to help.

2) "rezinn" states that I will be able to access the sensor from the underneath the car. "TunedPort350" - I know you said that I shouldn't force it, but (assuming the Chevy dealer is no help and there are no new posts) I see no other choice. I will try to force it into position from underneath the car.

Boy, I hope someone comes up with a better choice than this. ...I bought this IROC to autocross it and here I am just over a day before my first driver's school and it's screwed up.

Man, I am bummed out.

 

That's a metric thread, I'm almost sure...I used an old "spark plug no foul" thigamjig (highly technical term) I had laying around to screw into the O2 sensor bung to check my back pressure...as far as I know, all spark plugs threads are metric??

I have a thread gauge and I'm sure I have an o2 sensor around somewhere, tomorrow I'll see if they match up to the SAE threads, if not, it'll be metric for sure.

 

Take the O2 sensor back!

The new sensor should be identical to the old one. If not, the old one may be wrong, but I doubt it. Get a A/C Delco sensor...none of this 'Tomco' bull$sh*. A/C Delco is what the dealer will sell you, and for you, will cost more getting it there (I know, I'm one of their mechanics). Besides, most dealers parts and service depts. are closed Sat& Sun. 1 out of 2 sensor problems in these cars is due to cheap sensors, usually aftermarket no-name junk, second is old or faulty sensors. Go to you parts store and tell them you want a Delco sensor...they'll probably be stupid and try to sell you the 'Tomco" crap, but get the Delco. If not, go elsewhere. Be sure to do it early before the parts depots close. It should fit the sensor socket fine. I replaced one on my '86 IROC with a deep 7/8" O2 socket and it worked fine. Except for it being locked into the exhaust pipe. Only reason I buy dealer parts is because they work well (they should!) and I get discounts...It would cost around $70+ dollars at the dealer, $40-$50 I think at a parts store. Trust me. And compare the new Delco sensor to the old one (probably also Delco). I've had these problems more than one and found out they gave me the wrong sensor (after assuring me it was correct, and an 'updated' part). The A/C Delco sensor is probably 5-10% more expensive, but is by far better (those with no-name EGR valves and EGR codes take note). Should be identical. Except for the crud. If this doesn't work, then just find a plug or a bolt to plug the hole for the time being (right size thread)...you fuel trim will suck, but it'll run. Tuck the O2 wire up somewhere. Fix ASAP. Don't drive far, this is not healthy at all, but if you need the car, you need the car. Your call. Don't goose it. Good luck!

And no, this is not a sale gimmick for work (as some think). I get no brownie points for this. Just trying to help out. Keep us posted.



[This message has been edited by dhirocz (edited March 23, 2001).]

 

The saga continues...

I have learned the following from the my dad's friend at the Chevy dealer:

The O2 sensor does indeed have metric threads. Dimensions as follows:
14mm diameter
1.75 thread pitch

I also checked for a tap with the above dimensions. Very hard to find. A garage that specializes in exhaust MAY have it. No guarantees.

We collectively concluded:

1)I could try to find the right tap and proceed in this way. Given it is Saturday and today is my only chance, I ruled this out.

2) I could try to find an exhaust shop that could tap a new hole, plug the old one and live with it that way. I've mostly ruled this out because it is unlikely that I could get immediate service on a Saturday. I may revisit this one.

3) Get the AC Delco (i.e. correct) sensor and try to get it into the manifold through forcing it. I am going to try this... I just found the correct sensor at a part shop locally. (Not many Chevy parts departments open on Saturdays around here... nearest one was 45 minutes away)

If #3 doesn't work, I may try #2 depending on the time of day...

If things are not in a usable state by sundown, I plan to buy a new manifold (about $145) and start from scratch... However, I'm hosed for tomorrow if I make it to this point.

I've got my (bloody) fingers cross...

I'll check in later...

 

The saga continues...

First, the above information is incorrect. The closest tap size that I could find was 18mm with 1.5 thread pitch. According to the specialty tool shop that I just came from this is 2 mils off, but this should put me in a position to start the threads on the manifold.

I also found an AC Delco replacement sensor.

I'm off to fight the car and snow in my driveway...

I'll report back.

 

Game over. I lose.

After tapping the hole, there just want enough material left. I give up. I put the tap back in the hole, hooked up the new sensor and used wire wraps to keep it out of the way. I took the car for along drive and it runs good enough. I'll be taking it to driver's school tomorrow in it's current state.

Next week - new exhaust manifold...

Thank you all for the advice.

 

Keith O, go get a spark plug thread repair kit!!!!!!!!!!! 14MM threads are identical to modern small block chevy spark plugs. Take the manifold off and 20 minutes should fix your problem.

BTW the repair kit can be purchased at any parts store.

------------------
84 Camaro ZZ4 with HOT cam. 1.88 60' (12.98 @ 105MPH E.T.)
Recently Ported Heads, Installed Larger Race-Flo Valves and RPM Air Gap Intake (No new times)
Other Mods: You name it and I have probably changed it.

2001 Dodge Ram Quad Cab 5.9L 4*2

The Bowtie
ASE Certified Auto Tech
LIVE AND DIE BY THE ALMIGHTY BOWTIE!

 

Guys,

To close this.

I think I'll try the spark plug repair kit as a starting point.

By the way, I ran the car at drivers school without the O2 sensor (I left the tap in place). The car ran fine and the driver did OK.

These cars are a BLAST!

 

I am adding this with the hope that someone avoids this situation through reading this.

First, let me say that I honestly :
a) Heated the engine prior to trying to remove the old O2 sensor
b) Soaked it for about an our in a bunch of Liquid Wrench before again trying to remove it
c) Finally, I soaked AND heated it before trying a third time

I had to get that off my chest - my mechanic doesn't seem to believe me...

I took the IROC to my favorite mechanic and here is what he ended up doing.

1) Reamed the O2 sensor hole out to a slightly larger diameter.
2) Matched the O2 sensor's output to an O2 sensor that would fit the bigger hole.
3) Tapped threads for this new hole.
4) Put the new O2 sensor in the car.
5) Spliced the connector using the old connector.

This was cheap and works fine. I kinda feel stupid for not thinking of this myself.

 

Headers

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89 GTA G92
305 TPI WC 5spd w/3.45
Accel Cap & 8mm Taylor's
Custom 4" Cold Air Induction
Jet Airfoil
K&N Airfilter
160 deg stat/fan switch TB Bypass - Steel Rad
Cat back 3" Exhaust w/Terminator Muff.
HiGh FlOw Dynomax Cat
Spohn LCA's - KYB GR-2's
Moroso Crank Bolt and roller pilot bearing.
Autometer Vac+Oil Temp

 

I can never remove my oil filter by hand if the car is very warm to hot, but once cool to cold, I can always remove it by hand. Using that logic, I question whether it would have been easier to remove the O2 sensor while cold.

Regardless, I easily removed my old O2 sensor after 97K miles when cold. But of course, my threads were in good condition to begin with. Using a spark plug repair kit certainly sounds like the best solution for your situation.

I used an O2 socket from NAPA. Their 7/8” O2 socket is a lot thicker that the others I looked at (Pep Boys, Sears, etc.), so it is doubtlessly stronger. It’s also more expensive at $24 (in this case, you get what you pay for). Of course, a 7/8” wrench would negate the need for the special socket if it’ll fit.

I sprayed penetrating oil on the sensor every day for over a week before trying to remove it. I rarely have problems if I saturate a part with penetrating oil for several days (weeks?) before removing it – especially any nuts/bolts connected to the exhaust.

In the future, any time you need a hard-to-find part (e.g. a single tap or die in an unusual size), I would suggest you look at McMaster-Carr. They are an industrial supply center, reputable, and an excellent source for hard-to-find parts. Compared to a local harware store, the difference is night and day. They have a web page www.mcmaster-carr.com or www.mcmastercarr.com – I can’t remember which, and have a lot of hard-to-find items. They are fast, usually receiving my order within 3-4 days via UPS. I didn’t see any spark plug repair kits, but I did see 14x1, 14x1.25, 14x1.5 and 14x2 taper, plug and bottoming taps for $15-25 each on one page of their >3000 page catalog. Just don’t expect to receive a hard copy of their catalog. It is extremely difficult. I think e-bay had one a while back, and it was selling for > $100! There is a lot of discussion about the difficulities of obtaining their catalog on their message board. At least their catalog is on-line though.