Getting broken stud from head

I found it very difficult. I borrowed a stud remover (Like a left-handed corkscrew) from the machine tool section at work, then drilled the stud to engage the remover. However, the drill broke in the stud, which had become heat-hardened, and I was reduced to taking the cylinder head into work on the bus and leaving it with the Millwrights, who somehow removed it for me.

I didn't watch, because I couldn't stand the raucous laughter.

The heat-hardening of the stud was my downfall. :-(

Work like that is beyond the modern average garage, an engineering shop is the best bet. Attempted removal by an inexperienced fitter is likely to do more harm than good. Removal may be as simple as mole grips, or as complex as spark erosion. or many steps in between :)

If you had managed to drill it, the easi-out would probably have broken in it - and they are hardened steel so a PITA to remove.

If the head had got that hot, the engine would be toast. ;-)

My favourite way is to place a nut directly above the stud and MIG weld inside the nut to the stud. Of course if it is broken some way down inside the head, this may not work. The heat of the welding also tends to free things.

A drill at the wrong feed or speed will work harden the stud/bolt. You need a drill that can be set to a fixed speed to drill metal. Have to pay more to get one of those as the basic DIY hand drill is just regulated by the trigger. Then you have to be able to judge the feed.

Also metal drilling needs lube.

Drilling uphill on exhaust downpipe studs was an utter PITA. Needed cobalt drills and grease. The below wouldn't work as the exhaust, stud and flange are all ferrous. The time taken v's cost of new manifold and turbo/downpipe gaskets, taking the whole turbo off with manifold and then using a bench drill would have been better.

I've done this twice. Ferrous weld doesn't stick to ally head.

If it's sheared deeper then just build up with weld until its near flush.

A head stud or bolt will be high tensile steel which is pretty tough stuff.

What's far more likely is too high a speed/not enough pressure made the drill even more blunt than to start with.

You don't *need* 'lube' to drill metal. Certainly not for a job like this.

Studs into exhaust manifolds tend to get well and truly rusted in place. Due in part to the very high temperatures they see. A head stud only really sees the temperature of the coolant.

I'd not even attempt to drill one out in place.

I took it that the OP has got a broken cam cover bolt, rather than an actual head bolt. Depending on the design it may be possible to just leave it alone, if it doesn't leak :)

Yes it's the rocker cover & weirdly it's leaking oil into spark plug holes 1 & 4 ! It's one of the bolts at the back so you would think you'd get away with it though?

I took it that the OP has got a broken cam cover bolt, rather than an actual head bolt. Depending on the design it may be possible to just leave it alone, if it doesn't leak :)

If it were me, I'd leave the broken stud alone and refit the gasket with good bead of gasket sealant.

+1 It has to be worth a go and will probably work. I once sheared off a bolt in the engine block of a Ford Zephyr 6 whilst changing the head gasket. I tapped the remaining stud anti clockwise with a hammer and screwdriver, it came out dead easily. I then went out and got pissed to celebrate my technical expertise.

that is a fine way if the threads are not too tight and the stud is large enough. At a guess the OP stud is just 6mm (1/4 inch) across and that is a bit small for tapping round, a small left handed cobalt drill would be the first thing to try (if nothing is sticking out and welding is not an option)

Can you use a small cobalt drill hand held? Know it's not really practical with tungsten.

The left hand drill bits are very short, so they tend to be OK, I agree that longer thin drills are easily snapped when used hand held. I found years ago that if you use a centre drill bit (the type that is commonly used on a lathe) to start the hole everything is much easier. The other trick is to use a right angle drill, which places your hands nearer the action and reduces wobbling a bit. Lubrication of the site makes the chance of snagging less likely. Generally though it is rare that a broken stud cannot be removed with a weld/heat, drilling is a harder job and is easy to mess up, in which case I put in a Helicoil, or a larger stud with a reduced top bit, as appropriate.

Wouldn't have worked with my 25 year old Standard 10, and I just remembered it was a stud securing the exhaust manifold.

Well, it was about 43 years ago. The car cost me 25 quid and I sold it for ?15 with no MOT. Big bench seat, column change and as rotten as a carrot.

I converted mine to have a 3.4 jag engine with the jag seats and a floor change box, this was in the mid 70's. yes, they do rot. LNO 551C, long gone, but not forgotten.

If it's a stud on a flange joining the downpipe to the manifold, it's not normally a precision fixing, so simply drilling out and tapping to the next size up could be ok. I've even seem some where the flange is large enough to allow a nut and bolt to be used.

Different with something into the cylinder head, where there might well be a waterway close by. And it may also locate the part accurately.

It also depends just why the stud etc has sheared. If it is into ally, it might have corroded in place making it more difficult to shift what remains.

I always use a thread sealer for bolts or studs into ally - which not only locks and seals the thread, but prevents corrosion.

& you can get left handed centre drills.

I did not know that, thank you.

Got it redone & so far no leaks but the garage sheared off another one! I'm not bothered if it doesn't leak though

The bolts are very low torque (& small) from what I found and need to be tightened > > +1 It has to be worth a go and will probably work. I once sheared off

If it's a stud on a flange joining the downpipe to the manifold, it's not normally a precision fixing, so simply drilling out and tapping to the next size up could be ok. I've even seem some where the flange is large enough to allow a nut and bolt to be used.

Different with something into the cylinder head, where there might well be a waterway close by. And it may also locate the part accurately.

It also depends just why the stud etc has sheared. If it is into ally, it might have corroded in place making it more difficult to shift what remains.

I always use a thread sealer for bolts or studs into ally - which not only locks and seals the thread, but prevents corrosion.