Using a MIG to remove broken stud

[TouringMatt]

Read the threads, have washers, ability and a welder, but do i need to warm the area around the stud where i am going to weld first?

Engine is out the car so is stone cold, just worried about about heat/expansion/cracking/warping etc

Cheers!
Matt

[Ant]

no mate, you want the heat to weld the washer to the stud, then spread into the alloy as it "cools", spray a ton of WD on it a few minutes after and the stud will come out sweet

be careful when you arc up though that you dont burn the aloy back around where you're working, not good !

HTH Matt

[TouringMatt]

Cheers for the reply Ant.

Welding worked on 2, they did indeed come out sweet. The 3rd however was a complete biatch. Must have tried about 10+ times, each time the weld sheared.
Resorted to drilling it in the end, got the stud remains out but the top 1/3 of the thread got caught by my drilling efforts. Ran a tap down and tried an M8 bolt, although it does not feel too good it tightens up fine.

Question is, should i take it out to M10 whilst it accessible?

Cheers
Matt

[Ant]

Good effort dude !

I'd avoid going up a size on any stud in the upper portion of the head, the oilways etc are rather close in places.

better bet go for a helicoil and stick with M8 dude, safest option, and I doubt you'd get an M10 15mm nut in the space around the manifold

[TouringMatt]

Cool, helicoil it is then!

Nice one Ant

[Brianmoooore]

You can sometimes get away with a longer stud in cases like this. There's sometimes unused thread at the botom of the hole if the original stud didn't reach the bottom.

[Gt6s]

Good effort dude !

I'd avoid going up a size on any stud in the upper portion of the head, the oilways etc are rather close in places.

better bet go for a helicoil and stick with M8 dude, safest option

And exactly how is a heli-coil done then ?
I think you will find that it also involves threading out to a different size. Restoring to original size by means of a spring type insert.
But agree, heli-coil back to M8.

[TouringMatt]

Did wander that myself

Drill size for a M8 Helicoil is 8.3mm, M10x1.25 drill size is 8.5mm

Matt

[Gt6s]

Well I didnt want to get into specifics, but there you go.

Laurence

[Ant]

I think you will find that it also involves threading out to a different size. Restoring to original size by means of a spring type insert

thanks for teaching me to suck eggs mate, been doing this 16 years, always good to be kept on my toes.... not

good job I'm thick......... skinned

[TouringMatt]

Clearly i am thick though!

Whats the difference between drilling to 8.3mm/tapping for a helicoil and drilling to 8.5 and tapping for a M10?

Is it because the helicoil does not go as deep?

Matt

[Ant]

Helicoil is basically M9 thread on the outside, M8 on the inside

its a small diff I know, but given the cost of a replacment head, safe rather than sorry all the way mate, have a look for threads on oil loss from exhaust manifold studs

Only my advice folks, not to be taken as gospel

[TouringMatt]

Looks like ive fucked it lads, on closer inspection i could see something not right at the end of the stud hole, sprayed some wd40 down and can smell it coming out the water pump outlet

Scrapped head right?

[Brianmoooore]

Why can't the stud be sealed in, even if you've broken through into an oilway or the water jacket?

[m-dtech]

surley if its torqued up then its gonna be a pretty good seal anyway ?

[Ant]

Why can't the stud be sealed in, even if you've broken through into an oilway or the water jacket?

heat is the issue, no selant can hack it that I've found.

[TouringMatt]

Missus got home from work and thought someone had died from the expression on my face! lol

This has wounded me, not only cos of the cost but also because of the fact it was an 80k head but i dont like half measures. If there is no sure way of sealing/fixing this then its not worth trying imo

There is (touch wood!!) nothing terminal on my current engine, apart oil leaks and broken studs it runs cleanly. I'll probably pick up a head, get it tested/skimmed and do a full head rebuild and mate it to the 80k block, just take my time over it!


Cheers
Matt

[Brianmoooore]

All due deference to Ant's engineering skills and knowledge, but I find it difficult to believe that no sealant can stand the temperature. Away from the manifold and nearer the water jacket, the temp won't be more than about 150 C, I would think. Ordinary high temp silicon rubber is good for 350 C or so, and thats juist cheap mass produced stuff.

[StuBeeDoo]

All due deference to Ant's engineering skills and knowledge, but I find it difficult to believe that no sealant can stand the temperature. Away from the manifold and nearer the water jacket, the temp won't be more than about 150 C, I would think. Ordinary high temp silicon rubber is good for 350 C or so, and thats juist cheap mass produced stuff.

I've had exactly this problem. I had a broken stud drilled and helicoiled. The drilling has broken through to the oilway, and I've tried 4 different types of sealer. Nothing has cured the oil leak for more that a couple of days.
If I get any more broken studs, I'll be after another head. Seems to me that any drilling is a no-no.
Just my 2p.
Stuart.

[johnl320]

All due deference to Ant's engineering skills and knowledge, but I find it difficult to believe that no sealant can stand the temperature. Away from the manifold and nearer the water jacket, the temp won't be more than about 150 C, I would think. Ordinary high temp silicon rubber is good for 350 C or so, and thats juist cheap mass produced stuff.

I've had exactly this problem. I had a broken stud drilled and helicoiled. The drilling has broken through to the oilway, and I've tried 4 different types of sealer. Nothing has cured the oil leak for more that a couple of days.
If I get any more broken studs, I'll be after another head. Seems to me that any drilling is a no-no.
Just my 2p.
Stuart.

Did the ptfe liquid/tape not work then stu??

john

[StuBeeDoo]

Did the ptfe liquid/tape not work then stu??

No it didn't John. I tried that one a couple of times. Even tried some "high temp. sealant" (can't remember exactly what) and like Ant says, that didn't work either.
I have actually cured it with a bodge, but I'm far too ashamed of what I did to post it here. Needless to say, having done it, if I ever have any more head stud problems my head will be scrap.

[gcorky]

whats this all about with washers and a migset???

[dazleeds]

http://www.kalimex.co.uk/

have a good dig round on this site

ya never know they may have something

[Ant]

Matt, get the head stud hole welded up gain and re-drill/tap for M8 dude.

a lot cheaper than a new head, and as you say , the head is a good 80K unit on your car.

( OT, that engine came from my mates 70K SE, strong as an ox dude ! )

Brian, I've tried them all mate, JB weld is "supposed" to be the don, nothing works that I've found, but I'm still looking

[Gt6s]

I think you will find that it also involves threading out to a different size. Restoring to original size by means of a spring type insert

thanks for teaching me to suck eggs mate, been doing this 16 years, always good to be kept on my toes.... not

good job I'm thick......... skinned

Ant It was not the intent to give egg sucking lessons (dispite at this stuff 30 years to your 16)
and 4 Gawds sake dont take that remark too seriously either, aint a competition to see who is the oldest or has the most serious automotive battle scars !
Just found the remark about not taping out and heli-coiling a little bit contradictory.
All else on that post, total agreement.

Laurence

[Ant]

tongue in cheek mate, agreed its a bit of a non-point but the extra mm can make all the diff as you know

Dont worry dude, I've learnt to take everything in good humour, just sometimes that fails to be conveyed correctly on here, forums are all about opinions, long shall this remain the case

[Gt6s]

tongue in cheek mate, agreed its a bit of a non-point but the extra mm can make all the diff as you know

Dont worry dude, I've learnt to take everything in good humour, just sometimes that fails to be conveyed correctly on here, forums are all about opinions, long shall this remain the case

Indeed Cool
Oh yeah just to add, that bit bout at this stuff 30 years. That refers to after 16 Yo.
Previous to that knocking about machines and machine repair 16 years but will admit didnt get good untill I was 5.

Sorry may come across as a bit arogant @ times but thats only because I probably am bit arogant.
or as my freinds say
Rude, crude and socially unexceptable !

Laurence

[TouringMatt]

Ant, did you get my PM?

Anyways, found this http://www.easyweld.co.uk/

And these websites about using it here and here

Is this the kind of thing i need to use to fill the stud hole?

App i need to get the surrounding material to 372'c - will this warp the head?

Cheers!

Matt

[Ant]

Matt, PM recieved yes mate.

its not the engine I thought it was dude, my bad

anyways, that welding kit may be worth a bash, dont know how successful you'll be as the filler material is liable to be quite soft, using MAPP should not warp the head in anyway though, Especially when still bolted to the block.

Just be careful as poss, and run the engine up to temp ( loud but fun ! ) 1st, make the whole process safer, and faster due to heat being already present in the castings.

Make sure there is ZERO oil in the area though, welding alloy is a PITA without that causing more grief

HTH

EDIT: had an idea......... assuming you can get the M8 stud started in the remains of the thread, you could possibly use silver solder to secure it better and prevent the oil loss issue, silver solder has a very low melting point, is strong and will join ferrous and non-ferrous metals without any issues later on.