Extractor size...method?
 

I just broke the head off a 6mm head bolt, the one on the forward area of the head near the coolant hose housing. 2 of them one taller, I snapped the smaller one. Only fastener left to pull the head off and I am stuck.

What is needed to extract this broken bolt out. Size of drill bit used and extractor size/type used..............I also need a new bolt if anyone has a spare lying around.

Thanks in advance.........oh and hurry it has been 9 months since I drove this beast, help me get back to running!!.....I am sure you all can understand!!:cool:

Dal

Did it break off flush to the head, or is there a bit exposed?

Just below, almost flush. Head snapped off only.

If your lucky...
First use a center punch to make an indent on the exposed surface of the remaining offending bolt.

I'm not sure what size drill bit you would want to use without the bolt in front of me, but the rule of thumb is 1/3 - 1/2 the diameter of the bolt (thus leaving enough metal to to bite into without tearing it apart.

Then tap in an easy out. There are a couple different kinds, one had reverse threads for gripping in deeper the harder you twist, the other is a square shaft with biting corners all along the length of the shaft to grip the bolt.

Sometimes the revers threaded ones will slip and tear at the bolt, but then again there are times the square ones will brake off in the bolt... it's kinda your choice. If neither of these methods work, there is always the multiple drilling option. Start with a small drill bit and drill the center of the bolt out, then progressively increase the size of the drill bits until you have actually started to bite into the head material. Then use a (gulp) helicoil to repair the threads. Not a great option, but sometimes, it's the only option left.

we just did this on my friends 944, same bolt exactly. we did the step up method until it was nearly to the threads, then i retapped it. we are going to use a stud instead of a bolt and use the stiffest loctite made to stick it in there.

My plan is to punch, drill and extract but lost as to what extractor or size, believe it or not never had a busted bolt in my half a century, plenty of stripped threads but none w/the head snapping off. Looks like the bolt shaft is about 3/8ths to a 1/4 diameter so I imagine a 3/16ths drill will cut the mustard. Is the extractor needed the tapered, spiral flutted type?

thnx....Dal

Weld a nut and back it out....

The heat from welding will also help loosen it.

..... even seized bleeder screw that snapped flushed with the caliper will come out easily like this.

No way to weld a nut on and I am not touching any aluminum with a welder, you haven't seen me weld!

Thnx
Dal

Am I missing something here? Just lift the head off. The bolt goes all the way through the head and is threaded into the block. When you remove the head, the shaft of the bolt will be exposed and you can remove it with vice grips.

You are correct jwade........At first I thought it was threaded but the head popped right off. I have the bolt extractor for this application. The bolt is being soaked now before attempting removal. Well I do not see any valve damage either but some pitting of the head is noticable and much corrosion of the gasket. The gasket is in one piece though. One valve looks like it was salt/carbon corroded. :(

Dal

jwade944 beat me to it. I broke this bolt too and just took the head off and then removed the shaft.

I'd soak that bolt in Kroil first for a day or two. Even heating doesn't seem to help that much if it's corrosion...do not use an oversize helper bar, it will only break again. When you reinstall a new one be sure and slather that thing up with all the copper based anti-seize it will take. Those bolts are notorious for shearing off.