Exhaust hardware removal.

[theraymondguy]

The flex pipe on our car has given up. Usually exhaust hardware is problematic. Cutting the studs off might very well lead to replacing the manifold. Nuts must come off, I’ve had success in the past with an extractor socket - this time no go. This hardware started out life at 19mm, now a loose 15mm.

I’ve been at this for a couple of weeks now on and off. Wd40, nothing. Krown t32, nothing. PB blaster, nothing. Gentle Heat and beat, nothing.

2 applications of Kroil, tapped the socket on with almost no swing room and the remnant spins off like it was installed a few weeks ago.

Lots of videos on YouTube proving kroil is not as effective as its competitors, I say bologna. Saved my weekend and my manifold.

 

[69ST]

You're not going to like the answer. This requires "the blue wrench". Heat the nut until it's bright cherry red, then using either Vise Grips or a BMF pair of Channelock pliers, it will unscrew...complaining loudly. If that turns out to be impossible, the manifold can be heated instead (right at the threaded flange) then the stud can be unscrewed...and replaced. This is one old-school technique that hasn't changed. Cast iron tolerates extreme heating quite well.

The only other option is splitting the nut. A cutoff wheel works quickly...but...there's oftentimes insufficient room to use one, plus collateral damage is all but guaranteed. A nut splitter is safer, if you can source one. Once the nut has an open slot, it's loose. It's also possible to use it on opposite sides of the nut, cutting it (reasonably) neatly into two pieces and just peel off what remains, if anything. The stud threads should be chased, then coated with high-temp antiseize compound.

BTW, I've tried a number of different methods to prevent this from happening in the first place. Antiseize compound, during assembly, helps a bit. Believe it, or not, garden-variety grade 5 (or the metric equivalent 10.9) fasteners and the "blue wrench" for removal, once (inevitably) rusted is one of the better ways to go. Stainless studs + nuts tend to seize, though not as badly, leading to partially galled threads. Brass hex nuts are probably the best, with both steel and stainless studs.

 

[theraymondguy]

100% with you. My father was a welder/fitter, I grew up with an acetylene torch as much a part of my youth as Vice Grips. However, to be honest my kit is buried at the back of my shed, so it's literally the last resort. Most of the equipment I work on isn't exposed to road salt, and if the break down is serious enough the machine will likely end up at a shop of some sort - guaranteed to have a torch on site.

The Kroil I thought worth mentioning for those who don't have a set of cylinders and a torch at the ready. With time and patience, it provided the same if not better result - aided by a set of rather pricey Blue Point twist extractor sockets.