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FlyingDutchMan
14th March 2006, 20:30
Well I've been trying to remove the head from my CBR250 engine for a about a week now, and I'm finally stumped. I've managed to loosen all the bolts bar one. They were f**ken tight and required use of a 2ft extension on a 8mm socket. However, the one bolt left with which I have an issue with is a 10mm bolt. I tried a 12pt socket it promptly jumped off (the useful head is about 2mm high). So I went to a 10mm hex socket. Hard bloody work, then crack! I though it was loose, but I had just broken the socket. Grab the next 10mm hex socket. Try again. Again the socket breaks :angry2: teaches me for buying cheap sockets. So went out and bought a decent socket. And now I can't turn it at all - and if I'm not careful I'll round the head of the bolt. So grabed impact driver. Taking huge swings with hammer. Nada. Miss-aim one swing and it glances off the top impact driver and collides at a greatly reduced pace into my hand. Still hurts like fuck though.

So the question is: does someone know of a magical proceedure to remove the bolt? I'd rather extract it in one piece, but what ever happens, I will be replacing it. I suspect some bastard used lock-tite on the bolts previously.

stanko
14th March 2006, 20:33
try a rattle gun

nadroj
14th March 2006, 20:48
Heat the area of thread before impacting the bolt head.

miSTa
14th March 2006, 20:49
Freeze the little fucker with a can of freeze spray? Might be worth a crack don't know if it'll work though.

Sketchy_Racer
14th March 2006, 20:50
Ha ha......

I had the same prob with mine.

I used a Impact driver....and failed.

Then i tightened all the other bolt back up and used the impact driver..

SWEET!!

first hit.

give thata whurl

Ixion
14th March 2006, 20:59
Rattle gun, +1

Motu
14th March 2006, 21:15
Go and buy a 6 point impact socket - put it face onto a grindstone and take off the lead in,this will give you maximum contact with the bolt.Use a long powerbar with a piece of pipe on the end,keep the socket square on the bolt - left hand on bar,fully extended,don't use your arm muscles - then put the whole fucking weight of your body into it you wimp and crack that bolt!

Vagabond
14th March 2006, 21:15
If you have access to an oxy/acetylene set heat the head of the bolt red hot , being careful not to melt the bolt, then wait till you can touch the bolt with your hand, should come loose very quickly.
Tried and tested.

FROSTY
14th March 2006, 23:13
I'd try RG100's method first

FlyingDutchMan
15th March 2006, 08:42
Ha ha......

I had the same prob with mine.

I used a Impact driver....and failed.

Then i tightened all the other bolt back up and used the impact driver..

SWEET!!

first hit.

give thata whurl

Already thought of tightening the other bolts up and having a go at it... still failed misearbly.

FlyingDutchMan
15th March 2006, 08:49
Go and buy a 6 point impact socket - put it face onto a grindstone and take off the lead in,this will give you maximum contact with the bolt.Use a long powerbar with a piece of pipe on the end,keep the socket square on the bolt - left hand on bar,fully extended,don't use your arm muscles - then put the whole fucking weight of your body into it you wimp and crack that bolt!

Might go with this plan... while I'm still wrecking sockets. Anything as long as I can get the f**ker out. Leverage isn't so much a problem - its stopping the bloody engine moving all over the floor, while applying downwards pressure on the socket and not rounding the head of the bolt. Failing that, if I can find a oxy-acetelene thingie-ma-bob some where I'll have a go with that.

Crisis management
15th March 2006, 13:30
If the engine is not secured (moving around as you try impact or torque application) most of the effort is wasted with the engine movement. Clamp the engine in one place, refit all head bolts & torque up then try impact wrench on the stuck bolt. If its a nut rather than a bolt try CRC on it for 24 hours first.
If you go with the heat trick it will only really work if it is a nut - heat expands nut & loosens it. A lot harder to do to a bolt. Remember aluminium melts at @ 600 degrees!
Good luck.

Brian d marge
15th March 2006, 15:43
What usually happens is you get relative movement between the 2 and get this white powder stuff Oxide. Anyway it aint a lubricant.
Heat the offending area, the wife hair dryer isnt strong enough, ( you didnt give a location other thab a head bolt)

IF the bolt has enough. meat to support a decent wack on the head this is where you are heading, If its unsupported dont go there,

Now go to the car shop ( not super cheap ) and buy some penilube. The english stuff NOT WD40 0r CRC ,,,,The stuff I am thinking about is a penitrating lubricant , l comes in a squeeze can.

Apply liberally , go away ,,,, come back the next day , heat the area, Then with a drift filed to fit INSIDE the dish on the top of the bolt. and with a HEAVY hammer (a good ball peen hammer should be enough) .. give the bolt a good sharp whack, , One or two wacks should do it and As Motu says with a modded 6 point with the lead removed. try
IF it doesnt move Repeat said proceedure. Paitience is the Key. If it doesnt happen , crank up the heat ( IN the AREA of the thread if you can ) , Peni lube and wait.

Dont rush as a weld repair is expensive .

Stephen

FlyingDutchMan
15th March 2006, 16:14
Well I'll try and give a better description of where it is. There are 16 bolts holding on the head - 6x 8mm 12pt bolts, and the rest variations of 10mm hex bolts. The bolt in question is located between cylinders 3+4, UNDER where the cam gear train comes up. The 4 bolts that hold on the top two gears of the gear train are also holding the head on. There is another similar bolt located deeper down, but more towards the gear train opening which I have loosened. I cannot do up all the bolts as it requires the gear train to be in place (required spacer), and with it in place I can't reach the bolt. However I have done up as many bolts as possible and had a whack at it, which still didn't work. Because of its location, it will not be possible to head the thread without heating the entire engine block. Similarly, I need either a deep socket, or a socket extention to reach the buggar with a wrench. So there will be no using files on it either. So I can either apply heat, more force or a drill to it.

idb
15th March 2006, 16:35
Does this bolt go right through the cylinder block to the crankcase?
If so, by dropping the sump off you may be able to get some heat near to where the bolt threads in.

Set up some turning force on the bolt and quietly heat the area of the crankcase around the thread until the bolt hopefully lets go.
I would try a paintstripping heat gun on this.

Lazy7
15th March 2006, 16:43
get a high tensile Punch and hit it with a hammer on the corner of the bolt pointing towards the direction you want to turn it.

Ixion
15th March 2006, 16:59
Heta may be the answer if it has been loctited. Heat (VERY hot, not just "hot to touch") will destroy the loctite bond. This is an official BMW recommendation. A lot of their stuff is loctited with the stud grade loctite. Workshop manual says to heat the bolt/nut till it is really hot. Allow to cool, that degrades the loctite and frees the joint. It's not just the expansion of whatever it's threaded into (though that may help) it's actually to destroy the loctite that is holding it in.

Warr
15th March 2006, 17:02
From your explanation of where the offending bolt is..

I'd be rather inclined to drill the head off it. Just as you eluded to.

Groins_NZ
15th March 2006, 17:06
What about an "Easy Out" or bolt extractor - have you heard of them? Local hardware will probably sell them (Mitre 10, Bunnings, etc).

Motu
15th March 2006, 17:39
That comes after he's sheared the head off....should be too long I don't think....

Sketchy_Racer
15th March 2006, 18:22
Yes you can drill the top off then take the head out to get the rest.

but then you will be dropping filings into the bottom end of the engine.

And at 17000 RPM a tiny piece of steel on the mains will turn it to shit big time!!!

Pixie
17th March 2006, 13:52
If you have access to an oxy/acetylene set heat the head of the bolt red hot , being careful not to melt the bolt, then wait till you can touch the bolt with your hand, should come loose very quickly.
Tried and tested.
Redhot steel bolt = runny alloy thread

Pixie
17th March 2006, 13:53
Heta may be the answer if it has been loctited. Heat (VERY hot, not just "hot to touch") will destroy the loctite bond. This is an official BMW recommendation. A lot of their stuff is loctited with the stud grade loctite. Workshop manual says to heat the bolt/nut till it is really hot. Allow to cool, that degrades the loctite and frees the joint. It's not just the expansion of whatever it's threaded into (though that may help) it's actually to destroy the loctite that is holding it in.
Who's Heta?
Greek goddess of tight nuts?

Oh Heta, why did thou make my nuts so tight?

Ixion
17th March 2006, 15:30
HETA

H igh E xplosive T hermal A ction.

Get some glycerine, nitric acid, sulphuric acid . Mix together. Pour down the plug holes. Spin the engine . The head'll come off all right, Loctite or no Loctite.

Incidentally, if you have any nitroglycerine left after this (and you're back home from the hospital), you might like to utilise it to test this new discovery



A recent medical development will include a small amount of nitroglycerin in the tip of a new Durex condom to stimulate erection during intercourse. "The CSD500 condom contains a chemical in its teat, called glyceryl trinitrate (GTN), which is absorbed by the skin and causes blood vessels to dilate."


Oh, and tight nuts ? Try looser underpants.

idb
17th March 2006, 16:57
HETA

H igh E xplosive T hermal A ction.

Get some glycerine, nitric acid, sulphuric acid . Mix together. Pour down the plug holes. Spin the engine . The head'll come off all right, Loctite or no Loctite.

Incidentally, if you have any nitroglycerine left after this (and you're back home from the hospital), you might like to utilise it to test this new discovery



Oh, and tight nuts ? Try looser underpants.
By Crikey!
That's just crazy enough to work!!!!!!!!!!!!!!!

Vagabond
17th March 2006, 20:46
Redhot steel bolt = runny alloy thread
You obviously know JACK! So what would you do:wait: