Micra K12 Exhaust Flange silly bolts.

[bubba]

What a complete joke those exhaust flange bolts are, Nissan you are ridiculous!
Anyone with any sense would have either used brass nuts or at least bolts that are man enough, not the ridiculous set up you came up with NISSAN!!!!!!!!!

So, yes I have had to fit a lambda sensor on that exhaust and by far I am no newbie.
Anyway, so whats happened on mine is both bolts the heads snapped off, reason being it was much easier to get to the sensor by disconnecting this short exhaust pipe as on mine I could not get the sensor from above, even after removing the oil filter and getting this out the way, no chance underneath the thing was rock solid even with a hot exhaust.
Finally Sensor off and changed
So before I even attempt to remove those bolts I still have a decent length on the snapped off bolts, so my intention now is to firstly attempt to cut a thread in both stems and use a steel nut with another steel nut locking that and a brass or even two brass nuts to make sure this exhaust stays in place.
If at all that fails I shall use a torx socket socket small enough that would cut deep gooves when hammering socket into the stems, get some heat on the base of the cat and hopefully these bolts will budge?
If they don't then the third option is drill the bolts out, or fail that get the manifold off but really i would rarther like to avoid that.
I'm not the first and certainly not the last to come across this problem but thought I'd share..
Have images but not yet got them up here.

 

[Sparky2018]

What part of the exhaust are you trying to remove bolts from.
I have struggled with the downpipe to mid pipe flange. those bolts are frozen solid.
This bit I didn't remove but have replaced mid and rear back box.
The manifold was not wanting to remove also the left bolt was not wanting to remove.
My aim was to replace the shield and the whole pipe from manifold to back box.
I gave up on the downpipe bolts as they wouldn't budge.
Oh yeah and before I forget the manifold to downpipe bolts I replaced eventually.

Original plan was drop manifold with downpipe.

My conclusion so far with nissan is they can be alot of trouble finding parts.
Not to mention removing them.
Tryed most options with exception of the angle grinder.

 

[bubba]

Hey Sparky or anyone else doing this job.

Well I'm glad I never removed the manifold, that no doubt would have been a few more bolts snapped off..
Nissan and their stupid design on this down pipe with them bolts..

So this is what I did.. I left the snapped off bolts in the base of the Cat, I just cleaned the ends up of the snapped off bolts and instead cut threads down each shank.
Instead of your normal tap and die set I got hold of a die you could put in the end of a short but not deep 27mm socket, or you could use a 27mm open spanner and carefully cut some metric threads then securing the whole down pipe on those now threaded bolts with steel nuts locked into a copper or brass nut or two brass nuts locked together.

The springs if you have a vice and a good grinder I trimmed down the springs but the whole thing is perfect without them.
I'm going to sell the car now anyway, It has a ridiculous fault on it so all this work was for nothing, and after what I have just read about the power steering I don't want it.
So get this ridiculous fault sorted and get rid..
The car drives awesome from cold not a flutter, soon as the blue temp light goes out it starts messing about like holding back, no acceleration almost like having a blank spot.. Pull over switch off cool down and the car drives brilliant again, I suspected it was one of the Oxygen sensors but no it seems both of them were OK...
On here some place somebody has the bolt order numbers and I'm sure you can buy them on Ebay, or Amazon.
If nobody wants to do what I did then get a dremmel or angle grinder cut the broken bolts off, center punch and drill them out, if you try drill down the center the bit left in there might tap out, but I would be careful tapping around on the bottom of that cat because it feels like its cast iron and the casting of that is probably crap anyway.
Either that get a good quality stud extractor, some propane heat and carefully heat the bottom of the cat around the broken bolts they should budge.
Totally crap idea on them bolts and I hear the same sort of set up can be found on some Toyota's not sure which.

Or if you don't mind paying for another pipe take your car to an Exhaust center and tell them you want a new pipe, they'll probably say but there is nothing wrong with your old one, NO Demand it, at least this way OK you'll pay but at least they will have the job of getting the bolts out.
Saves you messing about on the floor!

 

[Sparky2018]

I been testing with canned air to freeze bolts that stick this so far worked on the brake line I struggled to loosen.
Worst case the do snap had that happen.
My problem area is the manifold at the alternator side if you are happy to remove everything to get at it and replace most parts it may be possible to remove.
I was fancying my chances at cutting the nut with a cold chisel and carefully not damaging the threads.
This would be a miracle.
The other option is to heat and freeze I do think this option especially the freeze method does help.

When I get back to work on the micra it's all brake lines and drums and unfortunately this isn't my favorite job although I'm still willing to hold on to the car until I get stumped by a task that isn't do'able.
If the reverse gear gives up probably I will be looking for a new vehicle to replace the micra with.
Would be a shame to give up when I have most parts already.

 

[bubba]

Could not be bothered to either use heat or drill them out tapped a new thread.
It works and really no hassle.