I recently replaced my crankshaft position sensor, and in the process I managed to shear off two exhaust studs in the left exhaust manifold. I'm referring to the studs that fix the exhaust Y- pipe to the exhaust manifold. What methods have you successfully used to remove these studs? The studs are sheared off below the surface of the exhaust pipe flange, so I do not have access to grip with vice grips. I can drop the exhaust Y-pipe but I'd be risking shearing more studs on the right side, since both sides have to be disconnected to drop the Y-pipe. I'm going to try to avoid removing the exhaust manifold from the cylinder head since I'd be risking shearing of exhaust bolts/studs in the head.

These are two methods that I'm familiar with and am considering:

1) EZ out extractor
2) Weld nut onto sheared stud

Either way, I plan on applying PB Blaster to the threads over a period of a few days prior to the extraction attempt. I'm not sure I'll have the room to try the EZ Out extractor, I'll have to take a better look later on when I get a chance. If I attempt the weld nut onto sheared stud method, I'll have to buy a welder. I'm also considering buying a torch to apply head to the stud immediately prior to extraction attempt.

Let me know what you think.

 

I went through this recently and found it was easiest to remove the manifold from the car. You can spray with penetrating oil and let it soak into the 8 exhaust manifold bolts. The passenger side is way easier than the driver side but both have ample access once things are out of the way. Not sure which two you broke but two of the studs are able to drill out to use a bolt and nut combo to secure. One (in the center) isn't so nice and you'll need to drill and retap that one. I would caution the use of an extractor though as i broke one in mine (and it was the annoying one that doesn't go all the way through the casting) so I had to machine out that hole to retap it. I would just avoid that headache and just drill from the getgo. If you're really lucky, you have some stud sticking out still once you get the manifold out of the car and the ypipe flange out of the way.

Good luck! I always presoak my manifold bolts now with penetrating oil to avoid this headache in the future. Hope it doesn't fight you too much!

 

The manifold to head bolts never shear off because they are steel in to aluminum. If you value your time at all I suggest getting a replacement and pitching that one. Ebay, Will Tillerey, FB sellers. Have not put them on the website yet but will be launching a kit of stainless studs and copper nuts for exactly this reason, $36 for a set. I already have them in stock, you can email me if interested.

 

I've busted plenty of these and I wouldn't bother trying to fix them in situ. Ever. Pull the manifold off and do it on a bench. Drilling it out and replacing the stud with a nut bolt combo (as suggested) is an easy way out, but if you don't have success with the busted ones after about 15 minutes, follow Extinct's advice and pitch it for another. Good chance I've got some here. If you're interested send me a PM and I'll take a look.

 

I had to remove two, one from each side, when I bought my Disco sans cats. I drilled them out. But I have a bridgeport clone that makes fast and precise work of that kind of operation.

Absolutely remove them. The removing the manifolds is easy.

 

Seems like manifold removal is the suggested method from people that sound like they've done this many more times than me, so that's what I'll do. Thanks for the responses.

 

I did have one shear off when I replaced the headgaskets in May 2010. Luckily for me, the bolt twisted off just under its head, so I was able to go ahead and remove the cylinder head and then easily get my Vise Grips on it to remove it from the block.

And better yet, there's nothing special about the "special" 12-pt bolts that fasten the exhaust manifolds to the cylinder heads. On the advice of forum legend P.T. Schram, I replaced the broken bolt with a standard hex-head 3/8-16 bolt of the same length from my local big box home improvement store and all is well 13+ years later.

 

I was coincidentally looking for something else in a box of miscellaneous parts today and found the sheared off manifold bolt. I had no idea I'd saved it. I also found my PMs with P.T. from the time, and was reminded that the bolt actually sheared off during reassembly, and at only the initial 11 lb.ft. step. My guess is that it got stressed on removal, and then failed on reassembly.

 

I fixed it. Removing the exhaust manifold went well. Not a single sheared bolt. I live where things don't rust very much so the bolts came out smoothly. I had to take the AC compressor off of its bracket to make enough space to pull the manifold out. After the manifold was off, I was able to remove the studs with vice grips. Once the vice grips were clamped on, I had to rotate them back and forth until it eventually was able to be rotated all of the way to the left.

AutoZone saved the day. I was able to find a pack of studs and nuts for the up pipe to manifold fasteners. The size is M8-1.25. The studs and nuts went in smoothly. All is well.

Now all i need to do is fix all of the other little problems!

 

Glad it worked out. I found getting the cats connected back to the manifold on the drivers side to the hardest part of the whole ordeal.