o2 sensor stud bolt broke off?

i bought this truck just last month, i went to fix the upstream o2 sensor on the downpipe and one of the bolts is completely gone? i tried to get another bolt (same size/thread) and see if it would just go back in but the threads were messed up.

do i need a new downpipe? do i need to take off the DP and tap/die it? if i got a little smaller bolt and went threw the bottom could i weld that myself to the DP and still create the seal on the gasget?

 

You might get by with just chasing the threads instead of an oversize tap, I'd try that first, I wouldn't remove the pipe to T & D it unless I couldn't do it on the truck for some reason..

 

Mine did the same thing. What I did was weld the flange, that the o2 sensor screws into, to the downpipe flange. I also cut the remaining stud off and plug welded the flange in the bolt holes. Now it is sealed and if/when I change the o2 sensor, all I have to do is unscrew the sensor. I don't have to fight the seized nuts or anything. Also my downpipe was fairly easy to remove. I took it off to do that and then I took it off again when I installed my AFR sensor.

 

a friend had suggested welding the flange on, i thought it was a good idea but my concern with that is the gasget?

i took it to master muffler just to see what they would do, and his "smart" idea was to cut out a 6" piece and put another one in with a new flange kit?
anyone see this a little extreme?

 

Meh, not really, he has to put his name on it by doing it & a new flange would assure him that its not going to develope into an exhaust leak

 

X2. That's actually the correct way to do it other than replacing the down pipe completely.

The only reason I welded the flange was because I have a welding machine and I had already tried tightening the crap out of the remaining stud but it still leaked. So I figured, if welding it worked, then that would save me the aggravation and money of bringing it to a muffler shop and so far it's working.

 

Oh, I know, I'd prolly just weld the whole damned thing up too...

 

yea my friend works at an autoshop so i can take off the DP and take it to him and he could weld around the whole flange? or would it be better to weld a new stud in?

think that would be the cheapest? the muffler shop was 80 parts + 55 labor+ taxes... normally i wouldnt have a problem paying that much but ive only worked 32hrs a week for the last month

 

I don't remember it being possible to weld in a new stud. From what I remember you would have to weld the stud in from the backside so that the flange would sit flush on the exhaust flange.

 

yea there is a hole all the way threw the DP flange already that the same size bolt almost fits all the way threw.