Oxygen Sensor Thread Chaser

[nitroman]

http://www.lislecorp.com/tool_detail.cfm?detail=1365
Once your car is a Lotus Classic (as Lotus says in the States to keep us away from the dealer-network) it needs special attention, much like your girlfriend.

If you are lucky enough to remove your O2 sensor without stripping the threads (From my own experience this is an excercise in patience. Keep applying a WD40 type product every day, and use no more than a 1/4" breaker-bar... as your 1/2" breaker-bar will remove the sensor AND all the metal which you used to call threads!) then you will need a product like this to clean & 'purify' the threads before they completely rust away into oblivion. This is also crucial if you wish to have an accurate reading when using a torque-wrench to install your new sensor.

In a pinch you can use an 18mm spark plug as they have the same thread-pitch (Elans use 14mm plugs unfortunately, but plugs are cheap & easy to find), however plugs are usually designed to screw into aluminium heads and not rusty cast-iron, so they may not be up to the task.

Anyhow, these can be found at O'Reilly Auto Parts but are a non-stock item, meaning they'll be delivered the next morning at no additional charge if you just call-in. Or, To locate a source for Lisle products in the US and Canada contact us at 712-542-5101. They will ask for personal information, like your ZIP code.

[nitroman]

I just want to point out that ONLY replacing the O2-sensor on a car with 27k miles makes a HUGE, HUGE difference. The car idles like a V-12 now, starts quicker at the turn of the key, and probably produces in excess of 700hp; although my math is a little rusty (much like the old O2 sensor!).

The combo of the 30k change interval & the fact that it was a 17-year-old sensor made more of a difference than any of you can imagine. I have to say I really got my money's worth from it. I'm now wondering how many more MPG it'll bring. Don't let your car get by on an antique sensor.

Wurth Rost Off the base every day for a month though, or you'll have a really bad day.

[Ellie]

Since, it seems, I shall be going through this very exercise real soon, I now realise that it will not be so very soon as the penetrating oil will need some time to work, and I will need time to work.

I dips me lid to you, Sir, for the advice herein. Where would we be without LEC? (Could be made into a catchy jingle on the site by one of the very imaginative co-contributors, I imagine).

[Ellie]

The Gods in Elanland are smiling today , and have visited upon me the joy of just a few minutes work with a 22mm spanner to remove a sensor that I know to be at least 8 years old.

[dermotbell]

Was the O2 sensor only on the Fed models?

[GeoffSmith]

Was the O2 sensor only on the Fed models?

All S2's are closed loop so have O2 sensors and Neil (enright) has converted his SE to closed loop.

Geoff

PS the Elanland Gods must be down under, because my sensor is refusing to budge.

[nitroman]

Don't get all manly with it Geoff. That's what I did with Elan #1 and it spit out the sensor along with the threads. I stuck to a 1/4" breaker-bar this time and kept lubing the threads daily.

For installation I lubed the threads with anti-seize, the same silvery stuff I use for sparkplugs. If I had nothing better to do in life I'd even loosen/tighten it every month or so; but even I'm not that anal. I did do that for several months following the 1st debacle though. After that car was totalled the sensor came out with no problem!

[GeoffSmith]

Don't get all manly with it Geoff.

I've been heeding your earlier advice Matt - liberal amounts of penetrating oil and generous amounts of torque.

[Ellie]

I have observed some things in researching and doing this task:
1) The threads in the manifold are not shiny - indeed, I would say 'rusty'.
2) The sensor came out with the spanner and some gently eased pressure from a pipe extension (do not hit the spanner or jerk/shock it as the sensor hex may be damaged). It is possible that the heating & cooling cycle when in service may 'normalise' (soften) the steel body, thus reducing its strength. Bosch says in its info that a 22mm spanner or a sensor socket will do the job.
3) Sometimes when components are stuck fast, heat will loosen the fit, so you might try to do the job when the manifold is quite hot but beware of working with hot surfaces, and for safety use thick gloves to protect from burns. You only need to loosen the fit, not wholly remove the sensor at this stage.
4) My initial thought was to put liberal amounts of anti-sieze on the sensor threads (my preference is for 'Never-Seez' [silver colour] or 'Koprcote' [copper colour]), however, the information I have been reading of late suggests that the manufacturers already place an anti-sieze compound on the threads before packaging, and there is some evidence to suggest that over-lubrication can be a real problem that can cause contamination of the sensor element.
I have decided that when I fit a new sensor that I shall place a very small amount of Never-Seez (which works really well on exhaust components, and has the benefit of being electrically conductive - an absolute must with the sensor as the body/manifold fit is the electrical earth return path for the sensor current), AND that I shall apply this small amount with the tip of a toothbrush around the manifold threads to give a really thin coating that is controlled in its application.

[Ellie]

Woohoo! Sensor arrived today , fitted it today , engine starts & runs well , goes like a rocket .

Noted some things with the pack contents & info - see below & pics.

Walker Oxygen Sensor Part No. 250-23127 (Isuzu (4) 1990-92 3-wire terminated)

"Oxygen sensors, if installed, are NON-returnable. Be sure to compare this sensor to the old one BEFORE installation."

Package contents - sensor with 3-wire connector, small tube of antiseize compound (copper coloured), instruction sheet.

Characters on inner plastic pack: 250-23127 IMO35 000 04C4

"Terminated Oxygen Sensor Instructions
1) apply 'high temp' antisieze to the oxygen sensor threads if not already coated.
2) install oxygen sensor into exhaust manifold and torque to 35 Ft Lbs.
3) on flanged applications [not Elan] install flange to exhaust manifold first, then mount sensor in flange. Note: a copper gasket is bonded to the flange and no additional gasket is required."

********* I used some of the antisieze in the pack - just a smear (too much may contaminate the sensor) which I applied with an old toothbrush to the manifold threads, not the sensor threads. It's the manifold that is cast & therefore rusty.

Not having a sensor socket (the type with a slot up the side) I used the same 22mm open ended spanner (wrench) that I removed the old sensor with. 35ft.lbs is not much, so I used the 'spark plug principle' - hand tight then 1/4 turn more, then checked that the seating ring on the sensor was compressed to ensure a tight seal.

[nitroman]

I installed a new O2-sensor in my Mercury Capri XR2 Turbo last weekend. The check-engine light has been coming on intermittently for months now, along with a MAJOR bog at high boost when under 3500 RPM. I thought it was the engine computer cuz I had it modified years ago to add fuel-mapping up to 16PSI of boost, from the 10PSI factory mapping.

Just installing the new O2 sensor has fixed both these problems, so, if your check-engine light is coming on, don't assume an ECU problem until after you install a new O2-sensor.

[GeoffSmith]

Just installing the new O2 sensor has fixed both these problems, so, if your check-engine light is coming on, don't assume an ECU problem until after you install a new O2-sensor.

An advantage of ElanScan is that you can check the O2 output levels: If it's not swinging evenly above ~4V and below ~1V it's a prime suspect.