Disco 2 Exhaust manifold fun

Apparently I've thrown a stud. Didn't hear it happen, just started to hear a "phut" noise on acceleration. I only had the whole manifold replaced about 6 months ago when the previous one warped.

I'm going to go ahead and hope that this hasn't warped, extract the old stud through the manifold hole (hoping it hasn't stripped threads) and fit a new stud. Is a torque wrench an essential part of doing that? If so, what's the right setting for the bolt?

If that doesn't work, I'm going to attempt to remove the damn thing myself. In that case, what sort of place am I looking for to get it ground back true again? I'm in York if anyone happens to know somewhere.

Fun times ahead.

Find a bit of this a bit hard to understand. "Thrown a stud". Does this mean the nut on a stud has disappeared, or does it mean the stud has loosened in its hole? The stud can't have gone anywhere as you mention later on about it needing to be removed through the manifold hole.
If you've lost the nut but the stud is still well tight in its hole, I would leave the stud well alone, there is otherwise a chance of stripping the thread in the head or, worse still snapping the stud when you try to extract it.
If the thread on the stud is intact, you only need to replace the nut, with a lock washer and probably a normal flat washer under that. 18lbs/ft torque setting, which is a bit small for a click type torque wrench so you may need an old fashioned indicator type.
If the thread on the stud has gone you have two choices, neither of which is fun. The proper thing to do is to undo all the other nuts and take off the manifold, (there is more to it than that, see Haynes manual or other threads) then extract the stud as best you can. Once the manifold is off you can use the nut-and-locknut method, if you are lucky but you will need to soak the stud where it goes into the head over and over again with WD or your favourite penetrating oil, before attempting this, or you will strip the thread in the head or snap the stud. There are patent stud extractors on the market. I have one, it ain't much use and it bug5ers up any thread that might be there. Remember to turn the stud a tad clockwise to crack the corrosion holding it in before trying to wind it out and be prepared to do a bit of back and forth movements rather than trying to wind it out all in one go. If you are lucky and get it out you can replace it with a new one. If not, you are in the world of drilling out, using "easyouts" etc etc. (SOOO badly named those things.) Lefthand threaded drill bits can be handy, but these drill bits come in really weird sizes and so do easyouts so watch it if you want to use a combination of the two. Once that is done you will have to carefully drill the next size up to retap bigger and then put a bigger bolt or stud in. Then you absolutely will have to drill a bigger hole in the manifold. I had to do this job last summer and it did not go the way it was meant to!
You mention a bolt. There is no bolt, it's a stud and a nut.
"ground back true". Are you referring to getting the manifold ground back true again? if so any machine shop should do it for about £30 cash. I'd also widen the holes in the manifold by 1mm for those on number 2 and 4 cylinders and 2mm on number 1 and 5 cylinders.
If there is no, or little, thread left on the existing stud, there is a slightly less conventional way around it which really is not in the books but may get you temporarily out of a hole if not even for longer, and that is to diecut a thread the next size down onto the stud. Then you can fit a next-size-down nut onto it. With appropriate washers and a second nut to lock the first that might be OK. (Now I am waiting for all the other members to tell me that is not the right way to do it. They will be right but it cannot make it any worse I think.) For penetrating oil I prefer a mixture of ATF and acetone, (nail varnish remover). Brush it on. The acetone is really penetrative and the ATF is thin but highly slippery. Best of luck.

So I got distracted and put the car back together before checking the hole; but the nut has gone, and there's no stud protruding anymore; so either the stud has been ripped out of the hole in the engine block, or else the stud has snapped. I'm going to find out which later, and if it's snapped I'll try and get the remnant out through the hole in the manifold. I'm hoping that as it was replaced not that long ago corrosion will be minimal; but I'll give it a bunch of WD40 too. But if it will need a new thread in the engine block itself, I'm not planning on doing it myself.

Wrong word, sorry.

Yes, I mean getting the manifold refaced.

Stud could just have got loose and then fallen out. If the nut went first then the stud separately, you may be lucky and just need a new stud and nut. Perhaps whoever did the work 6 months ago simply did not tighten things up enough. If it has snapped off at the manifold but there is the thickness of the manifold left on the stud, then you may get it out, but only by taking the manifold off. A good torch and a small screwdriver to poke in the hole will tell you how much of the stud is left.
I take it you do not fancy running a tap down the old thread, or drilling, tapping a bit bigger and putting a new one in? I didn't either but did it in the end. Depends on how much time you have. Not a quick job. If the manifold was replaced 6 months ago and was sound then, it probably doesn't need refacing, if it does you should demand your money back. Also, if the job was done by a garage they really ought to be doing all this work as it looks as if they didn't do a proper job the first time.

Managed a little poking last night, and while its hard to see properly, there's definitely some hole that goes deeper than the thickness of the manifold. It feels more like it goes up and to one side rather than straight in - but I guess there could be a buildup of crud. I guess that makes it most likely to have come loose and fallen out; slightly worrying, but hopefully means it's just easy to screw a new strut in.

@Naf623 Without wishing to P on your chips, if your "proder" is going up and to one side rather than straight in then it could just mean that the stud broke awkwardly and has left a bit behind. See if you can slide a very small screwdriver in beside the obstruction and, turning it anti clockwise, see what if anything it brings out. With lots of penetrating fluid, you might be able to unscrew a broken off bit, but I think you will be lucky. Can you count the number of threads left by shoving a pick in as far as the obstruction then holding it to one side and gently bringing it back up counting each click as you go? At this stage I would not be thinking of putting a new stud in, I'd be thinking of cutting a bolt to approx the right length and then putting it in with a varying number of washers to get the right length then tightening it up gently. To give you a bit of hope, when I had to do the job, I was trying to drill out a piece of broken off stud and ended up pushing it still further into the head, but it was OK, so maybe there is a bit of spare room at the bottom of the threaded hole, which you can safely use to store rubbish, if you see what I mean. This is all very unconventional but it might get you along for a bit until you can take the manifold off and do the job properly. But I would put something in there otherwise the strain on the existing stud may well cause it to go on holiday in which case you would be going backwards not forwards.

The threaded core plug in my cylinder head failed a couple of years ago so I had to pull the manifold off (in-situ / still attached to down pipe) to replace the core plug. Whilst doing this I found out that both far outer studs (1 on cylinder 1 & 5) have snapped off in the head. My manifold had never leaked and I noticed it had 2 manifold gaskets fitted. I couldn't get the snapped studs out in situ so I decided as a temporary repair to just fit another 2 gaskets (& new core plug). It has been fine ever since and done many thousands of miles like this without any sort of exhaust gas leak. There is obviously a problem with the expansion causing studs to snap or manifolds to crack on the TD5 but leaving the far outer studs out with 2 gaskets fitted doesn't appear to be a problem from my own experience.

@Stanleysteamer what is the difference between putting in a new stud and putting in a bolt? I'll hopefully have time for a bit more exploration shortly.

If you have a stud, or studs, then it should always stay in place and therefore there is less danger of damage to the head, as you should just be able to undo the nut(s) and remove the manifold, also you can replace and accurately line up gaskets and manifold, whereas with bolts you have to fiddle about holding gaskets and manifold in place while putting in at least two bolts. I am sure there are other reasons like differential expansion rates read this to find out more. https://www.practicalmachinist.com/vb/general-archive/ot-ss-bolts-studs-n-nuts-manifold-75257/

That sounds like putting a new stud in is the better option, then? Even in my circumstances, given the new studs should arrive tomorrow anyway.

Doesn't matter, some more poking and I definitely can't get whatever is in the way out, let alone get a new stud/bolt in. The whole manifold is going to have to come off; just gonna take it to the garage next week, and cross my fingers for the 350 miles we're doing over the weekend.

Naf623 said:

Doesn't matter, some more poking and I definitely can't get whatever is in the way out, let alone get a new stud/bolt in. The whole manifold is going to have to come off; just gonna take it to the garage next week, and cross my fingers for the 350 miles we're doing over the weekend.

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You should be OK. I did well over 500 miles with my dodgy manifold blowing and various studs nuts etc missing. The garage will probably run a drill just the size of the inside of the studhole to touch the broken off stud and give it a central dip, to help centre the next drill bit, then drill with a much thinner drill bit, progressively getting wider until it removes the broken stud's metal. Trying easyouts at each go to see if it can get it out without damaging the thread. If they do get it out, then a replacement stud can be used, but if they can't then they'll either put in a helicoil or similar. Ali is such carp to put steel threaded bar/stud/bolts into see https://dsportmag.com/the-tech/three-ways-to-fix-damaged-threads/ H ope this isn't spoiling your Easter weekend. The people who replaced your manifold 6 months ago, are responsible for this one not holding so I would deffo be having a go at them if not taking them through the small claims track. Your car should have been good to go for a long long time after their attention.

Didn't make it. Half an hour out of York there was a "thhhhwurp" noise like a slug being blown out of the end of a straw, and a loss of power. Limped back home at a top speed of 50mph (turbo not kicking in). Looks to me as though the manifold has come even looser, although there aren't any more studs missing. But there's blackening around much more of the edge than before. Suppose there just isn't enough pressure anymore to power the turbo.

We'll find out Friday anyway.

Naf623 said:

Didn't make it. Half an hour out of York there was a "thhhhwurp" noise like a slug being blown out of the end of a straw, and a loss of power. Limped back home at a top speed of 50mph (turbo not kicking in). Looks to me as though the manifold has come even looser, although there aren't any more studs missing. But there's blackening around much more of the edge than before. Suppose there just isn't enough pressure anymore to power the turbo.

We'll find out Friday anyway.

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So sorry for you. The people who did the original work should be dealt with. Strongly urge you to get them to redo the work, and hope you still have the receipt for the original work. If they cut up difficult they only have one chance to put it right, under consumer law, in which case you could get it estimated by another reputable company, maybe even a Main Dealer, and then get it done elsewhere, sending them the bill. The Small Claims Track is there for you to use. I have used it many times, never lost a case, it's really easy, and cheap. They owe you the job properly done, or the cost of the job plus any extra work caused by their inefficiency.

It's the same garage that I'm going back to in the morning, I've got a pretty good relationship with them. But I'm not really sure how to approach basically accusing them of doing it wrong. What sort of thing might they have done badly that would cause this? Bearing in mind I supplied the new manifold kit, gaskets, studs etc. and not them - they could probably easily try to say that those parts must have been sub-standard.

Naf623 said:

It's the same garage that I'm going back to in the morning, I've got a pretty good relationship with them. But I'm not really sure how to approach basically accusing them of doing it wrong. What sort of thing might they have done badly that would cause this? Bearing in mind I supplied the new manifold kit, gaskets, studs etc. and not them - they could probably easily try to say that those parts must have been sub-standard.

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They are the professionals, not you. If they thought the stuff you brought was substandard they should have told you. If you have got the receipts for what you bought then you would have a case against the suppliers and the garage should not have fitted them if they thought they were not up to the job. If the threads in the head were weak they should have helicoiled them. As a customer. by law, they are the experts not you, you have done no wrong. If you are still worried search online for info about consumer law. Sorry this is a bit late, I was not "watching " this thread, if you want to get in touch feel free to PM me.

I'm OK on the consumer law side of things; it's how to broach it with the garage that I'm unsure about. If it were a big place, or somewhere that I didn't have a good relationship with then I'd kick up a fuss no problem. But I don't feel so confident and comfortable doing it with this little independent place where I get along with the guy and he's done us really well in the past - don't really like basically accusing him of doing a bad job.

Don't think you have to accuse him or anything, at least not at the beginning. I think just go in, look concerned rather than huffy and show him the issue. Just say that you are worried about it and concerned the problem will lead to yet more damage. Ask him how he thinks it happened. If he is decent, he'll offer to sort it out, no money required. If that doesn't work, he'll give you some story. At the end of the day, whether he is big or small, he still has a responsibility to his customer. I have just reread the whole thread back to the beginning, so have a question or two.
1/ What caused you to have the manifold replaced in the first place.
2/ Where did you get the new manifold from?
3/ Did the garage give you any advice/warnings that you ought to have heeded and didn't, such as "Bring it back after 100 miles to have the nuts tightened"?

I find it hard to believe that a decent new manifold could have warped that fast, but the only way to tell unfortunately is to get it off, and if it has warped to get onto the people who sold it to you. Did you keep the old manifold? If so, you could possibly get that one refaced, cut through the webbing and widen the stud holes by 2mm on the far ones and 1mm in the inners, (not the centres), then refit that.
Finally I suppose it is possible that the head itself has developed a fault, i.e. a tiny valley or crack through which the gases could escape, but this is beyond my experience and repairing that, although not impossible, would be a head-off/PITA job. Whatever happened it is unlikely to be your fault so although it will take time it should not cost you money, although Sod has a law.