Bugger - Snapped bolt

Hi all,

After some advice, noticed a slight oil leak from my RHS valve cover a few weeks ago and as it was due for a service in a few weeks thought I'd sort it then. Started today and found that the valve cover bolt has snapped off, with no bit of bolt to grab hold of.
As such i'm having a think about the best way to go about it and looking for a bit of advice on which method is going to be the safest and least likely to go wrong :-

1/ Drill out the remaining bit of bolt and re-thread using a heli coil
2/ Try to get out using a stud extractor
3/ Reverse drill bit and try that way?

Also would it be better the remove the cylinder head? - taking into account the possible problems that that may include (Exhaust studs etc) or do it in place and the disadvantages of drilling by a 'free hand' etc?

I've never used a helicoil or had previous experience of drilling out bolt's as such, never mind any in a cylinder head so I'm not rushing into it.

I'm not looking forward to it at all and I guess I could hold it on with just the 3 bolts and put up with the leak but I figure I may as well sort it now but just don't want it to all end up in

Any help/advice would be much appreciated.

If it's just sheared from being over tighten then it should now be loose.

Try getting something with a point on and taping it around [anti clockwise].

Can't tell from the picture - is the bolt standing proud of the joint face at all?

If it is, even by a small amount, you could try putting a saw cut across it with a junior hacksaw - this would allow a purchase with a flat screwdriver, and as 'boxer' said - it may not be that tight now.

If you do try this with a saw YOU MUST NOT MARK THE JOINT FACE AT ALL !!!!!!!!

If you're not confident DON'T DO IT!

"Easyouts", or stud extractors, can work - but again you have to be careful.
By their very nature they tend to expand the piece to be extracted, thus making them tighter. Or they can snap off, leaving a bit of hard steel in the stud, and this then makes accurate drilling-out difficult. I don't like 'easyouts' - over the years they caused more work than they've saved for me.

To drill out accurately using a hand-held drill also presents problems, especially when it's a steel screw in aluminium. It's hard to keep a handheld drill square, and the drillbit will veer into the softer ally if it's off centre. Much more accurate with the cyl head bolted onto the table of a pedestal drill. But that means head removal.

If you do attempt an in situ drill-out - do not try to drill the thread diameter, as this will obviously drill out the thread, and then you MUST re-tap and helicoil. The trick is to drill just smaller than the thread tapping size.
Accurately done the remains of the screw come out almost like a spring.

Again - If you're not confident DON'T DO IT!

And whatever you do - you must prevent any metal swarf from getting into the engine.

In short an in-situ drill out is possible, but care is needed.

Phil

If it's broken below the base, carefully use a left hand drill bit (smaller than the thread base diameter) & it will pop right out....Use a suitable metal tube to protect any bare threads when drilling....

The other thing you can try is unscrewing by using a center punch and a light hammer - tap near the edge with the punch angled in such a direction that it will unscrew the remaining thread - again this does work but take care as you can slide off and damage the softer alloy. I normally do this first and if it fails punch the centre as a start point for drilling. A small shallow pilot followed with a left handed drill and the drill slowly in reverse also works well.

I would avoid easyouts if at all possible.

Personally, I would do the following...


1) Make a cup of tea, drink cup of tea whilst examining and thinking about what you have to do...

2) Take centre punch and carefully put a punch mark in the centre of the bolt...

3) Make a cup of tea, drink cup of tea whilst examining and thinking about what you have to do...

4) using a small drill, put a pilot hole in...

5) see 1

6) Take your reversed drill bits, put drill in reverse and start off small and gradually build up in size...

7) see 1

8) if at any time you dont feel confident STOP and consider either

a) can you continue
b) take the head off and sort it out with a pair of grips / hacksaw and screwdriver
c) get someone in to do it

Good luck and remember that patience is a virtue, and measure twice, cut once etc...

cheers

Nate

After all that advise is it out yet

Thanks for all the advice, much appreciated - It's not out yet as I just had loads of tea and thought and thought, had a and thought some more.

I have thus come to the conclusions

1/ EZ out or whatever are out of the question, I would need to go 3mm and thats the smallest I can find which I think = it snapping and
2/ Don't really want to do a 1st time helicoil as it's probably not the ideal place to start, although I could pratice on something else I think I'll save that for later.

So that leaves drilling out using a left hand drill bit, it does make me nervious but if I'm carefull I still have the option of letting someone else do a heli coil.

After searching on 'tinternet I can't find any left hand bit's - Anyone know where I can get some? Probably want a 3, 4 and 5mm.

Cheers

put some silicon sealer around the bottom corner of the rocker cover. That'll keep it oil tight until the head has to come off for whatever reason. Then have it removed.

Loads of bikes out there with just three rocker cover bolts them on. And quite a few with just two bolts

Dallas said:

After searching on 'tinternet I can't find any left hand bit's - Anyone know where I can get some? Probably want a 3, 4 and 5mm.

Cheers

Click to expand...

http://www.diytools.co.uk/diy/Main/Category.asp?iCategoryID=2215

alimey4u2 said:

http://www.diytools.co.uk/diy/Main/Category.asp?iCategoryID=2215

Click to expand...

Or take a look at screwfix - spend 45 quid and postage and handling is free, and it is oh so easy to spend money with Screwfix

Cheers all,

I thought that 3 would hold but am just a bit worried about the snapped bolt rattling around in there, although I could stick that with silicone as well I guess - Think that I may try to get it sorted now rather than later depending if I get a case of the jitters once the drill is in my hands!

Cheers alimey4u2 I'll order some now and have I think while they arrive!

Sorted

Hi all,

Thought I'd post an update - It's out!

Not as difficult as I had 1st thought:-

1/ Didn't think I could get a good enough centre with a punch and I had a little bit of 'hole' to play with so I very gently used a 6mm drill bit and just drilled a few mm to get an exact centre og the bolt.
2/ Using a 3mm left handed drill bit I drilled a pilot hole to a depth of about 5mm
3/ Using a 4mm drill bit and my drill set onto the lowest setting I started to drill very slowly and the drill bit stuck.
4/ As the drill bit had a bit of purchase I just turned the chuck anti clock wise and the left over bit of bolt started turning out and out and....

Well chuffed now, thanks for all the help guys!

Gnus....Well done...

Well done bud