Front Cylinder Head

Hi all, well you may have read one of my recent posts about the header bolts shearing on my front cylinder head.
I spoke to a few garages about drilling them out and they told me that there would be an air gap inbetween where the bolt finishes and the inner cylinder head starts, so I would know when to stop drilling.
Well all was well. Just waiting for that air gap..... bugger! The next thing I know, my drill and right arm is covered in coolant!
Well I cleaned up and went back to inspect. Oh dear. The bolt was totally flush with the head. Not impressed.
Well I thought I'd have to replace the whole engine but then I realised I may just be O.K. with just replacing the front cylinder head. However i'm not sure if I would have done anymore damage, i.e. swarf in the coolant system?
Has anyone done this before and how easy was it? I'm also wondering if I can do it without dropping the engine?
Cheers guys and gals.

[northwind]

You can do the front head without dropping the engine, though it'll be awkward. It might well be easier with the engine out, can't say for sure though. Swarf in the coolant system... No idea to be honest, sorry...

And also SOrry to hear about this.

Front cylinder head removal with engine in is easy. Taking the engine out will give you headache for no reason. I wouldn.t worry about any swarf that may have got into the cooling system, if any has, it shouldn't do any harm.
www.moto-tech.biz

[embee]

Since you were drilling, and broke through so the coolant then came out, chances are that there's no swarf got into the coolant side and even if there was the odd piece I wouldn't worry. Drills are designed to lead the swarf out!

In your circumstances I would try a new stud with suitable thread sealant. It's never good design practice to have "through" holes into either coolant or even into the oily side of the engine, you'll see they are always blind on sumps, cam covers etc. Through holes will leak (trust me, manufacturing would love it but they will leak in volume production, you'll see staining round the bolt heads). Any through bolt designs in cam covers for example will have quite elaborate (= expensive) sealing methods.

Having said that, you can usually get away with it as a one-off situation where you can pay careful attention to what you're doing.

Carefully run a "plug" tap (i.e. a tap which is full size down to the end, not a tapered tap for starting threads) down the hole to get a clean thread, especailly at the inboard end.

Loctite 577 would be perfect
http://65.213.72.112/tds5/docs/577-EN.pdf
http://www.loctite.co.uk/int_henkel/...d=336&layout=2