Rounded off cylinder head bolt

[Bigrig]

Hi everyone, apologies this being my first post but I was going to do that once I got my car up and running.

Any way I've recently purchased a 1994 wrx with a blown headgasket($800) for the entire car complete including front mount and 3 inch turbo back and I've pulled the majority of the engine apart got the left head off now onto the right side.. Got all of the bolts off bar one which I noticed was really badly rounded off to the point it's almost smooth, so in guessing someone has been here before me and failed so just put it back together, what in wanting know is has anyone got any suggestions about how I should tackle getting it out as I'm sure you are aware it's not the most accessible spot unless your coming straight on and they are tourqued down really well. Cheers in advance for any advice

[Guest]

Can you get a welder down there?

[Rosssub]

Use a centre punch to put a good dent in the middle of the bolt head. Then drill it with a 5mm, then 12mm drill bit until the bolt head comes off. Remove the cylinder head and the bolt shaft will probably come out by hand.

Edited May 29, 2016 by Rosssub

[Bigrig]

Cheers for the advice guys,my idea was to chuck a socket over it and just weld inside the socket to weld it to the bolts head

[Guest]

 Bigrig said:

Cheers for the advice guys,my idea was to chuck a socket over it and just weld inside the socket to weld it to the bolts head

I did that with an avcs bolt which wouldnt budge and ended up rounding out. Impact gun wouldnt budge it. Took a big bar and a nice hot weld around a 13mm 1/2" socket.