Soon, I will be attempting to repair a broken exhaust stud on #2 manifold. I will need to remove at least that middle manifold (perhaps even the outer?) and the rest of the studs to get it out.
Not sure those studs have ever been removed. The nuts I replaced when I reassembled after a head gasket (I removed & installed the head with the manifolds on so no need to remove the studs)
I suppose I'll have some issue with those exhaust studs... and I'm wondering, since using heat is always an answer to stuck fasteners, why does nobody speak of trying to break loose exhaust with a hot engine?
After all, a hot engine would have heat already applied. What am I missing?
Exhaust Stud Removal
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danmartinic
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fasterfaster
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Well, everything else will also be too hot to touch so you won't be able to finish the job, and you risk burning yourself if you touch any other parts nearby.
Also, part of the goal with heating is to create a heat differential so the parts heat and expand at differing rates, and break up some of the rust or other bonds holding them together. These are already steel vs aluminum which expand at different rates so not sure how critical that is. Finally, ideally you're getting that steel to red hot, which does deoxidize the rust and break those bonds. But similarly, for aluminum red hot is too hot and you'll warp or possibly melt the aluminum in this case. red = 1300F = aluminum melting temp
Aluminum expands twice as much as steel at a given temp, so trying to remove them hot isn't the *worst* idea. Just don't burn yourself.
Also, part of the goal with heating is to create a heat differential so the parts heat and expand at differing rates, and break up some of the rust or other bonds holding them together. These are already steel vs aluminum which expand at different rates so not sure how critical that is. Finally, ideally you're getting that steel to red hot, which does deoxidize the rust and break those bonds. But similarly, for aluminum red hot is too hot and you'll warp or possibly melt the aluminum in this case. red = 1300F = aluminum melting temp
Aluminum expands twice as much as steel at a given temp, so trying to remove them hot isn't the *worst* idea. Just don't burn yourself.
Marc
88.5 951 M030 Red on Black
88.5 951 M030 Red on Black
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Tom
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Yeah, it would also be hard to get the header off before everything cools down -- especially since you wouldn't be able to touch much of anything...
Where did the stud break, and what's your plan for removing it? If there is enough stick out, the best best would be welding a nut on the end (assuming vice grips can't get it free). If it snapped off inside the hole, It's going to be a challenge to drill it out and fix the threads -- so likely a head-off repair.
Where did the stud break, and what's your plan for removing it? If there is enough stick out, the best best would be welding a nut on the end (assuming vice grips can't get it free). If it snapped off inside the hole, It's going to be a challenge to drill it out and fix the threads -- so likely a head-off repair.
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danmartinic
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Not sure how much is sticking out. Here is the piece that came out
If not enough is sticking out of the head to work with, my plan is to use the right-angle drill similar to this I found someone else did.. I already picked up the drill when I was in California recently
Not sure I will go to the trouble to make a jig. I have some LH bits and hopefully they will twist it out
What's interesting is I installed this manifold years ago during a head gasket job and unless I busted the stud at that time, it somehow broke on its own. I just started hearing loud ticking during morning cold starts.. which disappeared when warm.. and when I investigated, there was this loose exhaust nut-on-a-stud
Can they just break from not touching them?
Anyway... the point is on a hot or warm engine why wouldn't I try and crack the studs loose (not remove) then leave and do the rest of the job cold? Up here, it doesn't take long for the engine to cool back down even now that its May
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What's interesting is I installed this manifold years ago during a head gasket job and unless I busted the stud at that time, it somehow broke on its own. I just started hearing loud ticking during morning cold starts.. which disappeared when warm.. and when I investigated, there was this loose exhaust nut-on-a-stud
Can they just break from not touching them?
Anyway... the point is on a hot or warm engine why wouldn't I try and crack the studs loose (not remove) then leave and do the rest of the job cold? Up here, it doesn't take long for the engine to cool back down even now that its May
I would avoid drilling and use a cheap mig welder and a nut to remove the remnants of the stud. Lots of youtube videos showing the concept.
I would replace them with https://www.ebay.com/itm/205512232206, which has an external torx end which allows you to remove the stud without removing the manifold.
I would replace them with https://www.ebay.com/itm/205512232206, which has an external torx end which allows you to remove the stud without removing the manifold.
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danmartinic
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Lots of people recommend the welding but I would bet most of us have never welded anything, myself included
Not sure I want to master this skill on my 951 head
Not sure I want to master this skill on my 951 head
That break appears to be more-or-less flush with the head. If you're going to drill it out, I highly recommend the jig. Otherwise the bit is going to do its damnedest to wander.
As for getting the rest of the nuts off, get an inductance heater. Nothing else comes close in terms of utility. You may need to heat-cycle them a couple of times (with some penetrant in between) to get them loose.
As for getting the rest of the nuts off, get an inductance heater. Nothing else comes close in terms of utility. You may need to heat-cycle them a couple of times (with some penetrant in between) to get them loose.
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Tom
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Looks like it snapped off below the shoulder so most likely it is below the surface in the head. If you are going to try a right angle drill, I'd absolutely make a drilling jig. It nearly impossible to get a drill bit down the exact center of a broken stud, even then you have a perfectly straight shot at it.
Whatever you do, don't be tempted to use a hardened steel bolt extractor (aka EZ-out). They snap off inside the bolt frequently and once that happens, the problems if exponentially worse.
I hear you on the welding technique, although you can literally get a flux core MIG welder for less than the cost of a tank of gas these days. The weld won't fuse with the aluminum head so it's relatively safe from that perspective. That said, and despite all the YouTube videos, results can vary on heavily corroded bolts. Many times I've welded a nut onto a crusty old bolt like that only to have the nut/weld twist right off as the bolt continues to crumble under the welded portion.
Whatever you do, don't be tempted to use a hardened steel bolt extractor (aka EZ-out). They snap off inside the bolt frequently and once that happens, the problems if exponentially worse.
I hear you on the welding technique, although you can literally get a flux core MIG welder for less than the cost of a tank of gas these days. The weld won't fuse with the aluminum head so it's relatively safe from that perspective. That said, and despite all the YouTube videos, results can vary on heavily corroded bolts. Many times I've welded a nut onto a crusty old bolt like that only to have the nut/weld twist right off as the bolt continues to crumble under the welded portion.
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Tom
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Dan, these this post and my reply. If you want, I could make you a jig in short order, very similar to my water pump stud drill jig. Would be a worthwhile add to our growing list of 3D printable tools...
viewtopic.php?p=56922#p56916
viewtopic.php?p=56922#p56916
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danmartinic
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Tom.. I seen the Stomski Racing jigs.. they have one just for 951.. but it's, ahem, about $500 CAD
Meanwhile.. I got some of this great stuff while I was down there.. including a bag of stubby bits that came with the drill
I have these yellow studs that I think I got from Porsche 'just in case' back when I did the HG but I'm not 100% exactly from where. Of course, I find them after getting the black studs from FCP for this job
Not sure which I should use?
And I've had these for years.. Left-hand bits..
Would be a shame not to use this neat pile of tools 
In the first pic you can see a general jig of sorts and I was planning on using that.. came with the various sizes of thread-in adapters and you kinda hold it against what you're drilling so at least I'm 90 degrees
You think that would suffice?
Meanwhile.. I got some of this great stuff while I was down there.. including a bag of stubby bits that came with the drill
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In the first pic you can see a general jig of sorts and I was planning on using that.. came with the various sizes of thread-in adapters and you kinda hold it against what you're drilling so at least I'm 90 degrees
You think that would suffice?