6 replies to this topic

[Quicksilver-ash]

I tried removing the studs out of the cylinder head that hold the heater valve but 1 of them snapped flush so I drilled a hole in it so I could wind a stud extractor in but that snapped inside also so I'm guessing I need to drill a hole and retap the thread. What size hole do I need to drill and which size tap do I need?

[sonikk4]

The biggest problem you are going to have now is drilling out the broken extractor. A normal HSS drill bit will not touch it. So if you are lucky a Cobalt drill may but normally I use a small carbide rotary burr to remove the extractor.

It's a job that you have to be very careful with otherwise you will end up doing more damage.

[Quicksilver-ash]

I'm worried about doing more damage so been putting it off as long as poss. The car is almost ready for an not so needs sortinh . I don't know where to go from here

[dklawson]

As Neil said, your immediate problem is going to be getting the broken extractor out of the stud.

 

If you do not own a Dremel tool or similar you will need one. If you have a pneumatic die grinder you can use that instead.  Along with the tool, buy an assortment of 1/8" diameter carbide tipped burrs and cutters.  You will use the cutters to carefully cut away that hardened bit of broken extractor.  With that removed you can return your attention to re-tapping the original hole.  The only other alternative you have is to remove the head and take it to a machine shop so the broken extractor and stud can be EDM (spark) machined out.

[carbon]

If it is a standard head then may be quicker and cheaper to find another good bare head.

 

Someone should post a sticky on this forum : 'Don't use stud extractors!'

[sonikk4]

Stud extractors do work its just a case of knowing when to stop.

 

I had a very tricky broken screw to try and extract behind a Airbus A319 Fadec cable junction box. It was on a floating harness support, 6/32 screw. Not a good place. The extractors i used were in the end not capable of removing the screw so i very carefully drilled through the centre which took out the majority of the stud. I then went through with a 6/32 tap to clean the thread out and happy days.  

[KernowCooper]

And you need to spend serious money on good extractors, I have had mine since 1975 and they have removed to many studs to remember, if they cost £7.50 on ebay thats where the problem is - quality