exhaust stud removal

iamchappy · iamchappy's Garage

While looking over my exhaust studs I noticed a few were getting a little thin around the middle I would like to remove and replace with new.
Any suggestions on the best way to back those studs out without breaking them.

Would welding a nut on the end do the trick if there aren't enough threads left to backup 2 nuts against themselves.

john walker's workshop · 04-22-2004, 09:58 PM

chances are slim that you will get any original studs to come out, regardless of the procedure. they just tend to break. i have a drill jig with a hardened sleeve that positions a 17/64 drill bit perfectly centered over the trimmed off/broken stud and removes the shank completely, allowing the threads to be pulled out like a helicoil. maybe you can make something like that. a machinist friend made mine.

john walker's workshop · 07:04 AM

there's a pic of the tool 1/2 way down page one on this thread. the disc in the center is stepped, and taps into a shallow bore in the tool. different discs adapt the tool to the different exhaust port sizes. you need one good stud to use it.

SSI Superstars! jig exhaust stud&pagenumber=1

iamchappy · iamchappy's Garage

Looks like I will be busy fabricating that nice little jig today. I can use an exhaust gasket as a template. should I even try heating and backing them out.

Porsche_monkey · 04-23-2004, 08:28 AM

You can always drill and helicoil.

echrisconnor · echrisconnor's Garage

Is there any reason heating the heads with a double nut, or even vice grips wouldn't get these suckers out? If JW says they break, I believe it, but I'm still surprised that the assumption goes straight to "you're gonna have to drill 'em."

iamchappy · iamchappy's Garage

I was told today by a drag bike machinist who has been fabricating a cross over pipe for my turbo, that if I heat up the studs and put paraffin wax on them that the wax will suck up into the threads and they should back-out

Porsche_monkey · 04-23-2004, 10:11 AM

Okay, heat them, double nut them, pour wax on them, throw chicken bones on the floor. Weld the nut to the stud, put the positive from your stick welder on the stud, put the ground on the head, pulse the welder till the studs red hot, try and remove it.

Then drill it out when it breaks.

iamchappy · iamchappy's Garage

Lucky for me there are only 4 studs that need replacing all of the others look good.

echrisconnor · echrisconnor's Garage

do the chicken bones really work?

john walker's workshop · 04-23-2004, 10:59 AM

drilling without a drill guide is hit and miss. very easy to get off-center and leave a portion of the stud on one side of the hole. if you drill by eyeball, just be careful. it can be done, i've done lots of them that way, and you still screw up occasionally, no matter how good you are. centerpunch, look at the punch mark for a while and decide if it really is centered, move the punch mark if necessary by punching again at an angle, drill a small pilot hole, and finish with a fresh 17/64 bit. that will leave just the threads if you got lucky. then use a small pointed punch to work the leading thread out enough to grab it with needlenose pliers and twist CC-wise and pull lightly at the same time. if it's off-center, you have to dislodge the remains with the pointed punch, then drill for an insert. or you could totally drill out the stud after the pilot drilling, and tap for an insert. use the drill size recommended for whatever insert you use.

Porsche_monkey · 04-23-2004, 11:11 AM

If it's on the car do it by hand carefully, if the engines apart go to a machine shop. I've done both, by hand they were slightly crooked, and I had to grind the exhaust a touch to make it fit. But it held fine, and no-one knows it looks like like ***** up close.

Helicoiling on the mill they were A1.

iamchappy · iamchappy's Garage

I have had to extract many studs in my life time I know all about the misfortunes of off centered drilling and breaking easyouts off in the hole. I have good success with welding nuts on more so than backing nuts against themselves but I always try the later method first. The engine (3.0 79SC) is in the car (914) and the studs are not broken. I could run it as is for quite awhile but I am debating at this time to drop the engine for other maintenance, if I do I will replace those bad studs.