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Discussion Starter · #1 ·
I was finally preparing to remove the pre-cats today and encountered my first problem almost immediately.

I was only able to loosen the oxygen sensors a small amount; it is as if they are frozen after less than one turn. I have sprayed a good bit of PB Blaster onto them and tried re-tightening them and loosening again but they stop after the same small amount each time.

My Spyder is an '04 with very low mileage. I read how difficult the five manifold nuts and the three amigos can be to remove, as well as the heat shield bolts, but was not expecting this problem with the sensors.

Any advice, help, and/or suggestions would be very much appreciated.

Thank you.
 

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Discussion Starter · #3 ·
Thanks very much for your reply; much appreciated.

Actually, BOTH sensors barely move after I broke them free! Could it be something else other than both sensors being cross threaded from the factory? I don't even think I can tighten them back completely; that is how stuck they seem to be!

Please forgive what may seem like stupid questions, but how will I even be able to remove the heat shield to remove the manifold bolts without removing the sensors?

I'm so disappointed this has happened to me. How should I proceed from this point?

Thank you.
 

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...Please forgive what may seem like stupid questions, but how will I even be able to remove the heat shield to remove the manifold bolts without removing the sensors?
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I think if you unplug the o2 sensors' wires.
 

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As odd as this sounds I found that if you put brake fluid in a spray bottle and spray it on the threads and work the sensors in and out they will come out. I work for a dealer and actually keep a spray bottle nozzle on a bottle of brake fluid in my cabinet for just that situation.
 

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2003 Toyota MR2 Spyder 2.0L Stroker
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I've never heard of this technique, but it sounds like a good idea.

OP:
When I had difficulty removing an O2 sensor (not on a Spyder), I took the car to a mechanic.
He worked his ass off for several hours and I paid for it, but I came away without any skinned or bruised knuckles.
^_^
+1 I had one that was basically welded on my post cat on another car. I gave up and took it somewhere where they put it on a lift and gave it the business.
 

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You might try it with the engine hot just be careful not to burn youself.
Also light tapping with hammer.
You might try a suspension splitting fork(don't know name of tool) as lever while unscrewing.
If you can't retighten them then you are commited to finish job as leaving them loose could cause air leaking in and warping valves.If this is the case remove the header and get it in a vice where you will have access to prying up while unscrewing
 

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Heat often works wonders, I would try being very careful with a hot manifold. You have either cross theaded O2's or deposits inside the manifold. Moving back and forth may help loosen. A tap might be needed as well as a SMALL dab of anti seize on the threads before reinstall.
 
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