enigma662

It's almost like the car is trying to stop me from getting it running. I could have it done today if it wasn't for all these setbacks. One of the exhaust manifold to turbo studs has a nut stuck on the end. Over the past two hours or so, I've succeeded in getting it off almost all the way. It's still got a few threads stuck in it though. I went to OSH and bought a bolt to replace it, but the threads are the wrong distance apart and won't mesh. I've put the stud in a vise, tightened it with all my might, and tried to undo the nut, but it just turns the stud also! Is there anywhere I can find a matching stud, or a bolt to replace the stud and nut? I REALLY don't want to have to order one online and wait another week. Please help!

BlaCkPlaGUE

I know the dealer has all bolts and studs for stock ****. I remember when I was buying my gasket for the exhaust manifold it showed the manifold studs with part numbers on the sheet she gave me.

just a thought.

enigma662

Yeah, I could do that, but it'd still take a few days. I was hoping for somewhere I could go right now.

hotrodrx7

I'm pretty sure they are M10x1.50. You should be able to get a grade 8 bolt at Home Depot or Lowe's or one of the left coast equivalents that is the right length.

enigma662

You're right, that's the length, but the threads on the one I bought are the wrong size, they're not fine enough. This was at OSH, would Home Depot have more selection?

dgeesaman

iTrader: (7)

Why do you need to remove the nut? Once the stud and nut comes out, I simply screw the assembly back in again as it was. Or is this not the case?

You should be able to get an M10x1.5mm pitch bolt, but the heads on standard bolts is larger, so it still might not fit, or your tool won't have room to torque it. Mazda hardware is really the way to go, even if it's used.

Dave

rockshox

iTrader: (3)

mr metric on 10th

enigma662

I'm afraid if I try to put it in stud, nut and all, the nut's gonna get jammed and I'm gonna overtorque it and strip the threads in the exhaust manifold.

dgeesaman

iTrader: (7)

I think that's kind of unlikely as long as the threads are clean and you're using a torque wrench. That nut will never need to come apart from the stud again, so it's no big deal. Next time you go back in there, the nut and stud will come out together. Use a little copper anti-seize.

Even if it does get screwed up, it will probably shear off the stud directly below the nut. Then you can remove the turbos and have a hunk of stud to grab and remove from the manifold.

Dave

enigma662

All right, guess I'll give it a try. Thanks for everyone's help.

hotrodrx7

If you haven't screwed (no pun intended) the threads up on the stud you pulled out, just put it back in like that. The nuts are squeezed by the manufacturer to lock themselves in place and a lot of them come off stud and all. If you have access to a tap and die set, you can clean the threads up if they're not too bad. If you do have to get a home depot bolt, put it in the bottom and you will have more room to get a wrench on the larger head.

dgeesaman

iTrader: (7)

And put it in an accessible location so that you can get Mazda hardware and switch it later easily without removing the downpipe and other stuff.

Dave

CantGoStraight

You definatley want to go with dealer items here. The exhaust and turbo bols are special in respect to the temeratures the deal with. (kinda like the header bolts) are a specialty item. The reason the nut locks onto the stud is that they are a locking nut (generaly one time only) and when removing them they tend to bite into the stud gauling the thread and carrying the metal all the way to the end. I know this doesn't help your situation. But you may want to reconsider using anything other than factory. Jack

hotrodrx7

Grade 8 bolts are fine for high temp applications. They are not your standard A-307 hardware variety bolt material.

tt2323

any luck? i would also suggest using the stud/nut just like a bolt. Should work fine

dgeesaman

iTrader: (7)

Well, since they're metric, I assume you mean class 10.8 or 12.9

The mazda hardware isn't steel - it's some sort of inconel or monel alloy. I've got a couple different BOXES of various high-strength bolts from Mr Metric, Maryland Metrics, etc. IMO it was all a waste of time: the socket head cap screws required a cut-down hex head bit to install/remove, and the heads of standard bolts were all 16mm or 17mm where the Mazda parts are 14mm. I finally bought new Mazda hardware and I think it's the best. I'll ship all those M10 bolts to someone who wants them for $10 plus shipping since I'll never use them.

Dave

hotrodrx7

8.8 metric bolts are the ones commonly available at the home supply places near me. They are Ok up to around 500* C. Definitely just a temporary fix though in terms of fitment and long term performance.

skotx

Talk about sticker shock.... I recently learned that to replace the six or so M10 studs/nuts and the one M8 would run me about $80 going through Ray at Malloy. The 8mm stud alone was over $9, and the nut was $5.

I went with grade 8 manifold studs from Autozone, at less than $1 apiece.

dgeesaman

iTrader: (7)

8.8 has the approximate strength of a Grade 5. If you're thinking of Grade 8, then you'll be looking for a 10.8 metric class. Torquing them to 25ft-lb like the FSM recommends I think puts them right at their limit.

Dave

enigma662

Used a grade 8.8 M10x1.5x30mm bolt from Home Depot, found out the idiot at OSH gave me a 1.25 pitch after I specifically asked him if it was the right pitch. It's on the bottom front corner so that I can switch it out as soon as I get a new Mazda stud and nut. Thanks everyone for your help, I can finally move on )

palsor1

iTrader: (2)

dgeesaman,

When you say 25 ft-lbs, are you talking about the nut torque or the stud torque? I'm looking at page C-87 of the FSM, and it shows 48-57 ft-lbs of torque for the exhaust nuts. Unfortunately I can't find the stud torque in the FSM. I'm about to do this myself and I want to make sure I use the right torque.

- Andy

dgeesaman

iTrader: (7)

C-87 shows the exhaust manifold to block connections.

In the first post you mentioned the manifold to turbo connection. You'll find that torque spec on C-93, which is actually 32-42ft-lb. All my comments related to the studs at this connection.

I've always just turned the stud until they are snug tight. When you torque the nut, the stud receives the same torque and both end up at nearly the same torque. When you go to remove them, the nut stays on the stud because the nut has a retaining/locking design. You can re-use the pair again as a 'bolt'.

Dave