Broken exhaust bolts in head

[Powermyster]

I had to take the exhaust off the bandit and a couple of the bolts snapped. The one with the studs ticking out are breaking after I weld a nut on.. Getting hotter and shorter etc

Anybody got any ideas. Also when is the best time to try the nut after welding, while its still glowing or after letting it cool???

 

[GeorgiePorgie]

Did you have any of the studs proud of the exhaust port? all you had to do is heat them up and lock a pair of mole grips tight round the stud and twist.

Done this two days ago on my motorbike exhaust port,they would not shift so did the above method.

 

[Powermyster]

I thought the heat from welding would be enough. Should I break the bottle out and heat them up..

One is flush with the head. Any ideas for that

 

[ChrisJohnsSculpture]

If they're breaking off it's probably bet to let them cool naturally, steel loses about 50% of its tensile strength above about 500degC. Also giving them time too cool will allow the heat to soak into the head itself, which should help to loosen them.

Putting some penetrating oil on them while still warm may also help. Using freeze spray on the studs may help too but wait untill thy are properly cool or the thermal shock could crack them.

Four the one that's flush with the head, put a washer, or better still a thin piece of aluminium or copper with a hole in it over the stud, put a nut over the hole and try to weld it on. It will help if you countersink the hole in the nut a bit so you can do a proper weld right to the bottom.

 

[GeorgiePorgie]

The one flush with the head? I woulnd try to weld anything to it,I'd be more inclined to drill and lefthand thread tap it,welding too near the head could do some damage.

 

[wheresmejumper]

if its flush,use a small dremmel bit to cut a slot in the stud,to take a flathead bit.
then heat the head around the stud,and use an impact driver to remove

 

[kelsham]

The problem with heating the stud is that it tends to expand more than the head gripping the threads. You need to keep the stud cool while heating the area round it gently.

Langy gave good advice recently about buying Dormer drills to drill out a broken stud in my exhaust manfold fitted to my Jaguar XJ-S. I started at 3mm and worked up.

Regards Kels.

 

[tigler]

The technique I find works in 99/100 cases is to, swear profanely, loudly and dramatically, grimace wildly, shout personal insults at the offending item as though it were a person who you really loathe, drink profuse quantities of tea, indulge in a sequence of useless, ill thought out efforts to remove it as unrealistically quickly as possible, throw various objects around the general vicinity and swear profanely, loudly and dramatically again when it results in damage to some irreplaceable item which you are sure is a conspiracy devised by the stud and thrown object, then, realise the futility of the last 2 hours or so, calm down, drink more tea, have a rest and finally remove it in 10 mins !!!!

 

[Powermyster]

The head looks to be aluminium.

 

[GeorgiePorgie]

The technique I find works in 99/100 cases is to

There are easier methods to get rid of the wife.

 

[GeorgiePorgie]

The problem with heating the stud is that it tends to expand more than the head gripping the threads.

Didn't have a problem loosening mine after heating the studs,just got me gas burner torch on it for 20 seconds.

 

[Powermyster]

Disaster, I tried the oxy-acetylene on the bolts got one nice and red and still nothing, all rock solid. Made a mess of one and sanded it flush it finger sander, tried to drill it and not a hope with HSS bits...

Might have to wait till monday and try get cobalt bits..

 

[wheresmejumper]

youre not supposed to heat the studs!

 

[pedrobedro]

It sounds like they are stainless studs, get ready for some pain. Are you doing it with the engine in the bike ? Welding to stainless studs turns them into the tensile equivalent of chocolate but a drill will not touch them, you have my sympathy. I hate it when bike things go wrong.

 

[Powermyster]

Yep. Engine is in the bike. Figure my options are to try drill and re tap in place. Or take engine out and bring to and engineering shop!

What you guys reckon is the best bet

 

[outofthefire]

drill it as close to centre as possible, finish with a drill the right tapping size for the thread if your cock on central then use a tap to clear the treads. If your off a bit use a slightly smaller drill then with a sharp punch you should be able to collapse whats left of the stud in on itself then clean the threads with a tap. I have in the past when my skills were a lot rougher made a mess of the drilling out ended up jumping up a thread size from m8 to m10 there is an imperial size in between m8 and m10 but I cant remember what it is.

 

[outofthefire]

Another thing to try rather than heat is freeze spray, i've not tried it personally but I have heard people swearing by it. http://www.loctitefreezeandrelease.com/

 

[Welderpaul]

Another thing to try rather than heat is freeze spray, i've not tried it personally but I have heard people swearing by it. http://www.loctitefreezeandrelease.com/

Looks good. Think it is as effective as it claims?

Anyone tried it?

 

[wheresmejumper]

ive used it in conjunction with heat to remove turbo housing studs.not the exact one in the link but similar idea

 

[hareng]

Been meaning to get some of that freeze for ages.

Unless the high tensile studs been changed, it wont be stainless its too soft.
Just use decent drills Titex or something and keep opening up the size to tapping size, if centred. You can pick the thread out then if gone all the way through the stud.
Done loads of cylinder heads and irreplaceable items with nothing more than a variety of drills, angle air, battery, pillar, miller etc easy.
Just get a feel for the drill cutting and keep it square.