V6 Exhaust manifold stud

I have a 1994 XE V6 Extended cab pickup with only 85,000 miles. For the second time, one of the exhaust manifold bolts broke on the passenger side.
I know this is a common problem with this motor - and I know Nissan has some "improved" studs available.
Has anybody used these new studs? Are they really improved? What a pain in the butt!
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I also had a 1994 XE V6 extended cab that had the same problem. the prolem developed around 50k when I started to hear a knocking noise when I first started the engine, after the engine warmed up the noise would go away. I had the bolts replace and did not have any problems with the manifold when I sold the truck at 70k.

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They are improved. I've yet to see anyone complain of a second break with the new studs. That isn't to say it doesn't happen, but I've not seen it here.
Bob
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I just replaced all of mine on my 95. The 'improved' studs Nissan gave me were part number 14065-V5004 and said 300ZX Turbo on the label. Apparently Nissan doesn't acknowlege the problem and won't fix it if you are unlucky enough to make it beyond the warranty period before they break (passenger side near the firewall is usually the first to go), but they are quielty providing an improved replacement version so it shouldn't happen again.

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What bad things can happen if I decide not to replace the broken studs?
- Dave
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On Fri, 18 Jul 2003 03:45:39 -0700, Dave
- The exhaust manifold warps and you have to plane it or replace it. It's possible that's already happened.
- You fail inspection or get asphyxiated due to an exhaust leak
Bob
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Neal, just make sure you replace *all* the manifold studs when you do the job, not just the broken ones. Also check the manifold for warpage. Have them machined and you'll be good to go.
For the group: yes I finally did the studs on my '95 Pathfinder a few weeks ago. Terrible way to spend a day and a half but a proper screw extractor set and a DeWalt right angle drill made the SOOO much easier. Here's the link for those interested:
http://www.dewalt.com/us/products/tool_detail_check.asp?productIDV34
Home Depot carries them for around $190.00 so you'll still save a few hundred on labor doing it yourself and when you're done you have a nice new tool added to your inventory. ;-) Don't forget some titanium coated drill bits and the screw extractor set and you're good to go.
http://www.mactools.com/ProductDetails.aspx?ItemNum=SE10
Wil

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What did you do to make sure you were centered when drilling ? Also, did you just drill and extract, or did you have to drill some of them completely out to the edges ?
Bob
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I just used my `tricks' I acquired in the few years I worked in the Nissan shop. :-)
Basically I have a `feel' for this crappy job now. LOL
Seriously though, I soak the guts out of everthing the night before with Liquid Wrench and use it VERY heavily while I'm removing the nuts that hold the manifolds on. Sometimes you just get lucky and the studs will back out with the nuts. That happened on all but one on the passenger side of mine. Talk about luck!
Once the manifolds were off and the non-broken studs were removed I used a punch and a small ball peen hammer to heavily `mark' the center of each broken stud. Make sure your punch has a fine point and it will give you enough of a `dent' that when you start drilling with a 1/8" titanium drill bit (my preffered choice, but I'm sure cobalt or something similar would do just as good) you won't wobble off center. The MAC Screw Extractor set comes with a set of centering devices for each size drill bit in the case but they are quite cumbersome to use in close quarters although they do work great. Once you've done your first couple of studs, you'll get that `feel' for everything.
After the 1/8" bit, I enlarged the hold to 3/16" (I believe that was the size). Then I used the #2 extractor from the MAC Screw Extractor kit to remove the stud. When you drill, DO NOT go too far or you chance going all the way through the stud and into a water jacket. Should you do this, perhaps some J.B. Weld will save you but it's better to compare a new stud for length and put some tape on your drill bit to act as a marker of the maximum depth you want to drill out. It takes a few extra minutes to do that but then you'll know for sure you're not going in to far but yet you're going deep enough to give the MAC extractor an excellent bite. Also, don't forget to keep back out the drill bit to clean out the hole as you go. You're not trying to get it all done in one pressing action.
A tip for removing the old stud from the extractor so you can reuse the MAC extractors:
clamp the unused end of the extractor in a set of vise grips and then put another set of smaller vise grips loosely on the extractor just against the broken piece of stud it's holding. Tap against the smaller vise grips and the old stud piece will pop right off of the extractor. If the extractor doesn't look to have a `twist' to the area where the stud piece was, you can resuse it.
Wil
On Fri, 18 Jul 2003 22:44:42 GMT, 'nuther Bob

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