Stuck, rounded off inaccessable $%^& head bolts!

[TerryG]

To replace my damaged head(s) i have bought another 4.6 engine from a friend that has "gone porus" (so it's scrap but the heads are good). One head has a stuck bolt the inside front one which is awkward to get at when things are going well but after attacking it with a 4ft bar, impact wrench, irwin bolt remover and a hammer and drift i have resorted to trying to drill it out.
Does anybody know if there is a special method of doing this or if there are any drill bits that last longer than 2 minutes when trying to drill a strech bolt?
I have been going at it for 2 hours and i am less than 4mm in to the head and have burnt out 4 2mm bits trying to make a start.
Don't you just hate it when an afternoon job turns in to one that takes a week. grrrrrrrrrr..........

[Grumpy Northener]

Terry - Try cobalt drill bits - these are readily available through well stocked tool retailers / engineers supplies etc - they are made for drilling trough hardened / tempered metals - keep the drill bit as cool as possible with cutting oil - but WD 40 works also - start with a small diameter bit first and get as far you can / to full drill depth before up sizing in stages if required - this will make life a lot easier.

[jimmyybob]

If you have done 4mm in 2 hours then the material is just to hard. smash the block to bits with a large hammer.

[Willy Eckerslyke]

If you have done 4mm in 2 hours then the material is just to hard. smash the block to bits with a large hammer. :twisted:

I was goind to suggest the same, or get a Kango from a hire shop and do it quicker.

[tractorman]

Just don't put the Kango on the join between head and block

I suspect, even with a cobalt drill, there's a danger of going off line while drilling and ending up with another trip to the scrapman. At least scrap is making good money!

[TerryG]

I started with 2mm (as that was the smallest bit i had that would reach the head of the bolt) and have .5mm steps up to 10mm (as that is how thick the bolt is) but titanium coated bits just aren't man enough. Thanks for the "tip" about cobalt bits. i will order some from screwfix now have another go with my black and decker on saturday
I was planning on making the block, pistons, etc into a coffee table but if i don't manage to get it out by next week then i'm going to take an angle grinder to it and cut a few mm below the head then just pull hard and hope that the ally breaks without scratching the head (or is that a bit extreme).

[hillmanimpman]

had a simlar problem a few years ago with my imp engine snap the bolt off clear with face had the same problem drilling it only drilling out small bits in the end i brought a cobalt bit and got it out, had to helicoil it after tho been fine ever since tho

[hillmanimpman]

there's another way if there room, which there might not. try finding a nut the same size and MIG welding it on top it might just undo it with the heat of the weld and abit wd40 it might come undo

[TerryG]

I have bought a cobolt drill bit set from tool station. i'm moving house this weekend so hopefully i will get some time to try in the week.
I did think about welding something to the top but access is very restricted so i'm stuck with the drill bits. i am hoping i can get it off as i don't fancy paying "real" prices for a pair of 10 stud heads from a dealer (so i know they are good)
when i get it off i'll post a pic of the access problem and the result (either scrap metal if i get annoied and take a grinder to it or a liberated head if the drill bits work)
Does anybody know how much the ally in a rover v8 weighs? (so i can ask the scrapman for a quote )

[Young Farmer]

Can you get an impact socket on the headbolts? If so use the longest breaker bar you have, a 3/4 drive bar is ideal with a lenghth of scaffold pipe. If this will not move them ,hold them under as much pressure as you can and get someone to give the bar a smack with a sledge. This might work,has in the past for me