Cat sensor thread

[p0689109]

I am having a saga with replacing the rear cat sensor on my Astra G 2004. The base of it has welded itself thread wise to the boss in the pipe. With a bit of basic engineering I have managed to get it down to a bit left in half the thread. I would like to run a tap down but am puzzled as to what the thread form is and size. Using my thread gauge it shows 1.5pitch metric and 16g whitworth on the new sensor. Measuring the outside dimension of the thread form shows just under 0.7inch and/or 17.5mm. Are these sensor thread forms all the same size and if so what is it?

 

[anto44]

A standard lambda probe thread is m18x1.5

 

[8ob]

As @anto44 says they are 18x1.5, I bought one for cleaning up the threads on weld in lambda bosses. You are more than welcome to borrow it on the understanding that if you lose or break it you buy it.

Bob

 

[Ruffian]

You can buy new weld in boss for about 3 or 4 quid if it is truly knackered also.

 

[zeppelin builder]

I am having a saga with replacing the rear cat sensor on my Astra G 2004. The base of it has welded itself thread wise to the boss in the pipe. With a bit of basic engineering I have managed to get it down to a bit left in half the thread. I would like to run a tap down but am puzzled as to what the thread form is and size. Using my thread gauge it shows 1.5pitch metric and 16g whitworth on the new sensor. Measuring the outside dimension of the thread form shows just under 0.7inch and/or 17.5mm. Are these sensor thread forms all the same size and if so what is it?

same as the old 18mm spark plug thread
buy a tap or weld on a new boss

 

[zzr1200]

Tracey's tools select your tap and just order it.

https://www.tracytools.com/taps-and-dies/metric-taps-dies/18-x-15-metric-sp-plug

 

[anto44]

If you only need to clean out the threads. And not cut new ones then any motorfactors or halfords should have a thread chaser to do it. Sealey, laser and most tool companies that sell auto stuff do thread chasers for lambda probes

 

[anto44]

This is the chaser, they come with most sets of lambda sockets.

 

[pedrobedro]

Spark plug thread chaser will do it, I got a double ended one does two different plug sizes.

 

[p0689109]

Thanks lads. I have to replace the front pipe as the flexible bit has started to disintegrate at one end so I have got one coming. But I still want to clean up this old one as I hate being beat!

 

[doubleboost]

have welded sensors into stripped holes more than once

 

[p0689109]

Pity the poor sod who has to next remove it then!!

 

[colnerov]

All they have to do is take it back to John, then he can have another earner welding in a new boss.

 

[anto44]

https://m.ebay.ie/itm/Stainless-Ste...946397?hash=item20dde85d1d:g:PscAAOSw3qJZznY8

 

[Bill Edwards]

https://m.ebay.ie/itm/Stainless-Ste...946397?hash=item20dde85d1d:g:PscAAOSw3qJZznY8

Not worth not having a few in stock at those prices, if you're a garage.

 

[p0689109]

I actually had one of those thread chasers but would not touch it so followed advice and got a tap from Tracy's tools £18 delivered. Arrived next day and managed to clean up boss great. Thanks for the offer Bob but I would rather buy my own as I don't like lending tools as most people who ask to borrow are never reliable to return either on time or undamaged, in my experiences anyway. So just as well I had the tap as when I tried to fit the new sensor into the new pipe the thing would not screw in. I had to run the tap down it to clean the thread. I reckon after they weld the bosses in the pipe they do not clean the threads. All done and dusted know. On to the next saga. Welding my LDV!!