Quite some months ago I broke one of the valve cover bolts off in the cylinder head while putting the valve cover back on (i torqued it way too much), now there is the bottom half of the bolt stuck in the cylinder head and I can't bolt the valve cover down from this hole. So I just left the top half of the bolt sit in the hole so oil doesn't spit out of there badly (it still does, a little bit over time), but this is a vacuum leak and I was wondering if it's bad to leave this like this and how can i fix it? the bolt is broken off flush with the cylinder head so i can't really take it out

 

Post pictures.

You may need to drill out the broken bolt. Don't press down too hard during drilling or you'll dull the drill bit due to overheating. Also use a reverse drill bit so the bolt doesn't tighten further.

During drilling, cover the exposed internals of the head so as to avoid getting metal shavings into the engine.

 

Try a easy out first but cover the inside of the head to keep crap from falling down in when drilling. Maybe even a couple picks could get it out. If its not stripped and the threads felt good going in you shouldn't have to drill

 

it's definitely not stripped, it's in there normally, if i could just get a grip on the top of the bolt i could easily reverse it out of the hole. and i have a replacement bolt

 

If you cant do it take it to a machine shop, it's just one bolt so it shouldnt cost much. If you decide to do it, crumble up some clean shop towels and shove them in the valvetrain to keep shavings from going in and when you are done go over the area with a magnetic oil drain plug or something.

Use these

 

ya I would advise not using one of those and just take it to the machine shop

I have snapped one of those off in a bolt before and it cost almost 2x as much at the machine shop cuz I messed with it

probably 20$ and they will have it right out for you

 

if the bolt head is exsposed you can cut a slot in it with a dremal and use a screw driver to get it out ..Ive had to do that before on a mates car

 

That's a very good idea, I had a similar situation but mine was on the cam plate and I had no depth to try the method mention above. I use a drill to "tap" the head and then put in the reverse drill bit to extract the broken stud.