Penetrating Fluid (seized lambda sensor)

[hyperblue]

I tried to replace a lambda sensor on a Peugeot 106 earlier, but it seems to be seized. I had a 22mm sensor socket ( like this) on it with a 2 foot breaker bar and I couldn't move it at all. I've never found anything I couldn't move with this bar!

I sprayed some 3 in 1 penetrating fluid on it, but it hasn't helped. Can anyone recommend a good penetrating fluid or an alternative way of unscrewing it?

[JFReturns]

Heat it maybe?

[hyperblue]

JFReturns said:

Heat it maybe?

I'll give it a go, easy enough to heat up the exhaust manifold

[AceOfHearts]

Plusgas

[tank slapper]

Penetrating oil takes a while to work. You might have to put it on every day for several days before it does anything, and even then it might not work. Heat can be useful, but you want to heat the thing it is screwed into rather than the sensor itself. You can try a combination of heat and oil - heat them both and apply oil to the sensor to cool it. The contraction may draw oil into the thread. You can also get a combination freeze/penetrating oil spray that works along similar lines.

Be careful heating it up though, as getting it too hot can make it weak and break off when you apply force.

[voicey]

AceOfHearts said:

Plusgas

This. Once you've tried Plusgas you'll never use anything else for stuck threads.

[lgw]

Rost Off

[Clivew]

Diesel.

[phillpot]

tank slapper said:

. You can also get a combination freeze/penetrating oil spray that works along similar lines.

this is the stuff.

I was very sceptical, but worked a treat on some siezed seatbelt bolts (no way of getting heat on them without torching the car!)

[mwcr85]

Spray whatever penetrating fluid you decide on and run the engine to get it nice and warm. Try tightening it a touch to "break the seal" are you using a socket or a crow's foot?

[PhillipM]

+1 for plusgas!

[hyperblue]

Cheers for the advice, I've bought some Plus Gas so will give it a good soaking, warm it up a bit and try again!

[Jimmyarm]

Is the exhaust moving when you are trying to undo the sensor ?

Take it off the car if it is

Get a bigger bar or a scaffold pole too, O2 sensors always sieze in and take a fair bit of force to crack off.

[voicey]

I pulled both cats off my car yesterday - gave the threads a couple of soakings of PlusGas and the Lambdas came right off with an open spanner. To be honest I was expecting a little more resistance from them.

[Jaged]

hyperblue said:

Cheers for the advice, I've bought some Plus Gas so will give it a good soaking, warm it up a bit and try again!

How did you get on with the plus gas?

I have a seized one on the rear behind the cat on the jag.
Up high so not easy to reach.

I got to it with a crows foot, but it's a bit loose!! (Draper 22mm)
So worried it might round off the nut.


I'm pissed, as recently I change the rear one on an A4 and it came out easy!

[Evoluzione]

The best penetrating oil you can get (in the US) is the one you make yourself.

50/50 mix of ATF (power steering fluid) and Acetone has been proven to work better than anything else:

Penetrating oil ..... Average load to undo seized nut

None ...................... 516 pounds
WD-40 ................... 238 pounds
PB Blaster .............. 214 pounds
Liquid Wrench ...... 127 pounds
Kano Kroil ............. 106 pounds
ATF-Acetone mix....53 pounds