Stuck Exhaust bolt

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volox
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Stuck Exhaust bolt

Postby volox » Sat Mar 25, 2017 6:59 pm

I've got a 95 Pathfinder and I'm trying to get the passenger side exhaust separated from the exhaust manifold. With great effort I got 2 out of 3 bolts loose but the one on the underside nearest the oil filter simply will not break.

I've now tried nut breaker to no avail. It looked like there was a flame on the nut that was keeping it from breaking, so I ground the flange off on the side I had tried to crack; still no dice.

Now that I've mangled the thing and it still isn't coming out, any suggestions on how to get those two parts apart?


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eieio
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Re: Stuck Exhaust bolt

Postby eieio » Sat Mar 25, 2017 8:14 pm

volox wrote:I've got a 95 Pathfinder and I'm trying to get the passenger side exhaust separated from the exhaust manifold. With great effort I got 2 out of 3 bolts loose but the one on the underside nearest the oil filter simply will not break.

I've now tried nut breaker to no avail. It looked like there was a flame on the nut that was keeping it from breaking, so I ground the flange off on the side I had tried to crack; still no dice.

Now that I've mangled the thing and it still isn't coming out, any suggestions on how to get those two parts apart?
Though I'm not directly familiar with your model Pathfinder, I'm pretty good with frozen & broken fasteners. Can you post a clear photo of what you're dealing with?

volox
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Postby volox » Sun Mar 26, 2017 1:31 pm

Here's the photo...

I've cut pretty much all of the one side off and I still can't get the others side of the nut off.

Image

The nut in question is the bottom stud of the three on this junction between the exhaust and the manifold. Essentially the one closest to the engine block, hardest to get at, and impossible to get tools on.

Image

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smj999smj
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Postby smj999smj » Sun Mar 26, 2017 4:08 pm

Have you tried accessing it by removing the right front wheel and going through the wheel well?

volox
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Postby volox » Mon Mar 27, 2017 12:07 am

Thanks for the suggestion smj999smj, but that doesn't help in this case.

Even through the wheel well there isn't any better way to get on it because the fuel lines run up that side of the engine compartment so the swing into gap of the wheel well is blocked.

At this point it's not so much about how to get at it as it is about what to do with it. See the pictures and you'll understand why.

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eieio
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Postby eieio » Mon Mar 27, 2017 6:45 am

volox wrote:Thanks for the suggestion smj999smj, but that doesn't help in this case.

Even through the wheel well there isn't any better way to get on it because the fuel lines run up that side of the engine compartment so the swing into gap of the wheel well is blocked.

At this point it's not so much about how to get at it as it is about what to do with it. See the pictures and you'll understand why.
unfortunately from your picture, I can't tell which fastener you are working on. is it a nut on a stud, or a bolt? but either way, can you grind the nut or bolt head completely off, remove the exhaust, then extract the remainder of the ground off fastener from the manifold (even if you have to remove the manifold to do so)?

volox
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Postby volox » Mon Mar 27, 2017 1:28 pm

Thanks eieio

On the other side, it was 3 bolts that were on studs. On this side I had one bolt come off the stud; the other one the stud unscrewed - I guess the nut got hard locked to the stud.

So this should be a nut on a stud, but it looks like someone used a bolt with a larger flange on it than any of the others, which is probably why it's been so impossible to break loose.

Grinding the rest of it off was kind of what I thought was going to be the next step. Was just hoping there might be some other magic.

My only question is what to do if I grind it off and the exhaust still won't let go? If it was accessible, that's when I'd get the drill out; but in this spot I know I would never be able to get the drill on it.

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eieio
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Postby eieio » Mon Mar 27, 2017 4:50 pm

volox wrote:Thanks eieio

On the other side, it was 3 bolts that were on studs. On this side I had one bolt come off the stud; the other one the stud unscrewed - I guess the nut got hard locked to the stud.

So this should be a nut on a stud, but it looks like someone used a bolt with a larger flange on it than any of the others, which is probably why it's been so impossible to break loose.

Grinding the rest of it off was kind of what I thought was going to be the next step. Was just hoping there might be some other magic.
No magic really, just techniques, which depend on the nature of the problem.
If you were to look at a parts diagram, you could verify if all 3 fasteners were originally the same on that side.
If the one dogging you is different (and shouldn't be), it could be that someone at an earlier time installed incorrect hardware, and if that's the case, it may be cross-threaded or an incorrect thread pitch, which could really lock it in there (especially with rust present).
volox wrote:My only question is what to do if I grind it off and the exhaust still won't let go?

BIG hammer! :)
volox wrote:If it was accessible, that's when I'd get the drill out; but in this spot I know I would never be able to get the drill on it.
It may require manifold removal to extract it.

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smj999smj
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Postby smj999smj » Tue Mar 28, 2017 12:20 pm

It's very common for the exhaust manifold studs to break (and they should all be studs with a thick, convex washer and a self-tightening nut. Nissan later upgraded the stud and made it harder and issued a TSB. They recommend replacing the center and two outer studs, regardless of whether they break or not, plus any other studs that are broken. If any of the washers are missing, they should be replaced and you can get them through Nissan. You should also replace all of the self-tightening nuts. Right side manifolds are more prone to breakage than left. I've done quite a few broken studs on these engines. Some come right out and others can be a real pain, especially if they break flush with the head but the stud broke at an angle, making the drill bit want to walk towards the side and that aluminum head.

volox
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Postby volox » Wed Apr 05, 2017 11:03 pm

Thanks to both of you for the replies.

After some fun with the dremel tool I finally got that nut off from there. Someone had definitely used a nut with a flange on it; making it nearly impossible to overcome the rust friction. I had to grind a ton to get the remaining piece of the flange to let go of that stud.

Since the cylinder heads are coming out, replacing the stud on the manifold won't be a big deal - just one more thing to add to the list.

smj999smj - I think you were referring to the manifold to cylinder head studs. I am aware of the issues with those and will preemptively be replacing them while I have the cylinder heads out.
The stud / nut that I was dealing with is the one that joins the exhaust pipe to the manifold output. Different kind of problem. But thanks for your contribution and trying to help.

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Postby smj999smj » Thu Apr 06, 2017 11:29 am

Ok. Yes, I was referring to the studs on the cylinder head.


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