Broken bolt in head

[ollieboy]

I know this questions been asked a bit but when I searched I never really got a definite answer. I have a broken bolt in head that holds rocker cover on, how do I get it out? I've heard of easy outs but have also heard lots of bad things about them. The bolts broken quite far down in the head and although its not causing any trouble, no oil is leaking out I am obsessive compulsive and as long as its like that I will feel uneasy Would say an engineering shop be able to get the bolt out for me?

[RS13]

Drill it out, retap it, new bolt, Roberts' ya mother's brother.

[ollieboy]

Cool, I didnt actually know what retapping was until I just searched google, Awesome man thanks.

[strap-on]

try an easy out first though as it can be a bit of an arse tapping, at least if you try the easy out and it doesnt work you know you can drill out.

a little tip that i learnt, when starting the tap if you can get access to a drill press, and do the first few turns of the tap (BY HAND) providing the press is set up level, it means that the tap will be nice and even and not all off-center,

remember when you tap a hole to take your time and after every half turn, back off a little bit before proceeding again

[RS13]

Just be careful when you drill it, centrepunch the dead centre of the broken stud, and use progressively larger drill bits until you're at the same size of the original bolt, then get a tap set and rethread it. Don't just rip into it with a huge drill bit, take your time and do it properly, you don't want to damage the head if possible, and make sure you aren't drilling down too far by getting another bolt from the cam cover to compare for depth.

[ollieboy]

Cheers for your help guys

[darkwolf]

I know that through placemakers I can get a set of tools that will allow you to basically sleeve the old thread. Basically it is a process of oversizing the old thread and inserting a sleeve that matches the old thread inside the sleeve and the new thread outside the sleeve. This allows you to make the hole the same guage as it was initially. I myself have done a similar thing (for my motherboard on my pc ) with a drill press by using a tap and die set.

My way was to:

Drill the hole out to size and tap it.
Create a threaded rod at about 2-3 sizes larger than original whole to provide meat.
Drill out the threaded rod and tap it.
Insert original bolt.

IMHO this option is better as it allows you to use a heavier duty metal than that provided by a standard sleeve.

Hope this helps.

[RS13]

Sleeving the aluminium head with a "heavier duty metal" could potentially cause problems in relation to thermodynamics, metals expand to a certain degree when heated, I would imagine using different metals with different rates of expansion you'd run into problems? Try taking your oil cap off the motor when cold, and then when hot, its' near impossible.