Front lambda sensor thread size

[Gamith]

After struggling to get my front lambda sensor out it came out with less than a full turn all told. 

It's difficult to see but the thread on the old one is essentially stripped and the new sensor can't get started on the thread in the exhaust manifold.

 

I am thinking of getting a tap to cut out a decent thread but I'm not sure what size to go for - though my micrometer says 18mm on the outside (which got me to thinking that maybe it's the same size as a spark plug) so i have ordered M14, M16 and M18 intermediate taps and see which fits.

Does anyone know what tap size I would need to cut the correct thread?

 

I will give it another go this morning after changing the fuel filter (fun!) and I might pick up an 18mm spark plug to see if they can at least make a start on the knackered thread I currently have in my exhaust manifold, a replacement of which would be £1000. 

 

Hopefully someone will have an idea.

 

Edited March 22 by Gamith
Changed the picture to a better one, and to make my engerlish more better :-)

[Gamith]

For anyone who is interested / in need I have found that for my 5/2005 2.4lts Alphards front Lambda sensor a M18 x1.5 tap is what you want. I cleared the exhaust hole, while the same die (M18 x1.5) cleaned up the threads on the Lambda sensor - all went together though I only tightened it up a bit as I didn't want to strip it 🙂

I have since taken it for a blast up the motorway and back, plus some driving around, and it behaved itself and there was no engine warning light - which is a relief (for this time at least). Now I need to get an emissions test to see whether it has actually helped.

Edited Friday at 07:38 PM by Gamith
Added some details so it can be more easily searched for.

[Picasso]

Paul fingers crossed for pass on emissions 

[Gamith]

I will take it to the MoT place tomorrow and hopefully get them to run a quick test to see - if it's still too high I suspect I will book it into the Toyota Garage in Letchworth who do not seem to be averse to working on Alphards (maybe mine is the first one) to see what they can do.

If it's Ok then I will book it in for a proper test - after that it could do with a couple of tyres being replaced (advisories). We will see.

[Gamith]

Yey - the emissions test passed!

It's booked in for the full test on Tuesday.

I have changed both the offside tyres which were showing signs of wear on the inside.

The new tyres are on the front and the front nearside is now on the O/S rear.

The tyre people did an alignment check and found everything was within spec, though both the offsides were right at the limit of the manufacturers spec.

 

I am rather pleased that the emissions look to be so clear cut - I don't know what the 'before' figures were but a CO and HC of 0 must be good. I'm not sure what Lambda is measuring but that is within spec also.

 

Oh we also found that one side light (far offside) doesn't work, and one brake light (nearside tailgate) doesn't work - both are dual filament bulbs, or at least they are different brightnesses for side and braking. I have put in some LED brake light 'bulbs' which do the same job, but are quite a bit brighter. It will be interesting to see whether the MoT tester says anything - or is it just LED headlight bulbs that are an issue?

 

Roll on Tuesday.

Edited Saturday at 08:18 PM by Gamith
Adding the broken bulbs - who knows, someone may care about it!