Broken exhaust manifold stud

[skucera]

My wife's Range Rover cracked an exhaust pipe Sunday. The section that broke was between the catalytic converter and the exhaust manifold. Luckily that section unbolts, and the rear part, with the catalyst, came right out. The forward part, bolted to the exhaust manifold, was a little harder. Two nuts came off with lots of penetrant and slow, even pressure. One nut broke its stud so easily that I think some previous mechanic or owner over-torqued it.

So, I've got the unpleasant job of removing the broken stud. I've only got about 1/4 in. of it coming out the bottom of the manifold flange. That's not enough length to screw two nuts to and wind it off. I don't want to saw a slot in the end because then the stud becomes so much weaker, and if I buggar it up then it becomes that much harder to get out. Does anyone have any ideas?

Thanks for any ideas,
Scott

[Paul Grant]

Heat. Heat. And more heat. That's the best way to remove it. Get the area on the manifold glowing red with a torch not the stud itself. Acetylene works best but MAPP can do it in a pinch. You might have to remove the manifold to gain proper access so be careful removing the eight bolts that secure it to the head.

In the future a word to the wise. Always use an impact wrench to remove the nuts from the studs on the manifold. When you do it by hand you are continually building up torque until the stud snaps. Using an impact wrench reduces the amount of torque the stud sees. At the worst, the stud will come out WITH the nut still attached. I almost never break studs when I use my impact wrench.

Good luck.

[skucera]

I saw last night that I had only about 3/16" of threads, but I had another 1/4" of unthreaded stud above that. I cut some new threads on that part and cleaned up the broken threads on the tip of the broken stud, but I just couldn't get enough threads on the second nut to crank them together and turn the stud out. So much for plan "A".

I appreciate your idea about heat, but I don't have a welding torch. I also want to try everything I can before I have to remove the manifold. I've never had good luck pulling steel manifold bolts out of an aluminum block on engines this old, so I'm leery about doing that cavalierly.

Plan "B" will be to cut a slot in the broken end of the stud, clean up the treads again, put a nut on it to keep the sides of the stud from spreading out, then turn it out with a screwdriver and a wrench for leverage. We'll see how that works tonight.

Plan "C" will be to remove the manifold, put it on a drill-press, and drill the stud out. (Yeah, I have a drill-press.) Then I'll re-tap the hole and proceed. Let's hope it doesn't come to this.

If I didn't need to weld something only about once every five years, it would sure be nice to have welding equipment. Maybe someday....

Scott

[atvsmurf]

I know you don't have the equipment, but if you could find someone to bring a welder by, or if you could drive it to them(i don't figure you can) then you can put a nut on, thread it up then weld the end of the stud to the nut, turning it into a bolt, then remove it...the torch idea could be pulled off with the little propane torches, which is what Paul was talking about with the mapp gas...

[Paul Grant]

Well, should you find that you need a manifold, I have a number of them for sale. They're $35 each plus shipping. If you want that ceramic coated I have them that way too.
Good luck,
Paul

PS MAPP gas is available along with small torches at most hardware stores.

[skucera]

Hmmm... welding a nut on the stud sounds like a great idea, and way easier to do than drilling the stud out.

I didn't think of a Propane torch. I've got one of those. I would definitely want to have the manifold off the car for that. I just don't trust open flame in any engine compartment unless all the fuel lines have been removed. A family friend burned his garage down when I was a kid because he tried to solder a wire connection in his engine compartment with a Propane torch inside the garage, and he burned his hands pretty badly trying to push the car out into the driveway.

I didn't get a chance to attack the stud tonight, but I've got all day tomorrow. We'll see what comes of the day.

Thank you all for the great ideas.

Scott

[skucera]

Well, after Plan "A" failed, I tried Plan "B" and it failed too (I bent a 20-year-old screwdriver that had never bent before... ever). I took the manifold off and welded a nut onto it, then promptly sheared the stud in half almost flush with the flange. Grrr....

So, I drilled it out after all. After all this frustration, it was so quick and satisfying to spend less than 20 minutes drilling, then 30 seconds with a reverse-twist 1/4" drill bit to wind the remainder of the old stud right out. I cleaned up the manifold bolts and had the whole job done in an hour after that.

The only drawback after it is all done is that the guy who welded it didn't weld the two halves back together totally straight to one another, so the flange behind the cat contacts a bolt head on the frame that it used to clear by 1/8" before. Oh well....

Scott

[pie4foou]

yea i'm very fond of the mapp torch... use them at work for many things. handy little buggers! get a burn-o-matic there great